- Systematic pH Study on the Acid- and Base-Catalyzed Racemization of Free Amino Acids To Determine the Six Constants, One for Each of the Three Ionic Species
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Computer analysis of pH profiles for racemization of four amino acids at 142 deg C led to the determination of the six absolute rate constants, one for each ionic species of amino acid in aqueoussolution catalyzed by hydronium and hydroxide ions.A comparison is made to show the effect of using all six constants to express the observed rate constants, as opposed to using only four in previous studies.The analyses also allowed the calculation of amino acid pKa values at elevated temperatures.
- Baum, Rocky,Smith, Grant Gill
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- Asymmetric synthesis of amino acids by Cr(II) complexes of natural amino acids
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Stoichiometric reduction of the C,N double bond of oxime precursors of α-amino acids was performed in aqueous media by Cr(II) complexes of natural amino acids. The reduction of oximes of α-ketophenylacetic, α-keto-β-phenylpropionic and α-ketopropionic acids proceeded up to >90% conversion and 2-30% enantiomeric excess. 1:2 complexes of Cr(II) with l-alanine, l-valine, l-aspartic acid, l-histidine and l-phenylalanine were used as reducing agents. The reduction of α-(oximino)phenylacetic acid showed increasing e.e. (and decreasing conversion) with increasing temperature.
- Micskei, Károly,Holczknecht, Orsolya,Hajdu, Csongor,Patonay, Tamás,Marchis, Valér,Meo, Milena,Zucchi, Claudia,Pályi, Gyula
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- Stress degradation study of bortezomib: Effect of co-solvent, isolation and characterization of degradation products by UHPLC-Q-TOF-MS/MS and NMR and evaluation of the toxicity of the degradation products
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Bortezomib (BTZ) is a first-in-class, potent reversible inhibitor of proteasome used in the treatment of multiple myeloma, the second most common hematological cancer. Stress degradation studies were performed to investigate the inherent stability of the drug according to ICH recommended guidelines Q1A (R2). Stress experiments were carried out in two ways using acetonitrile and methanol as co-solvents under various conditions. A selective stability-indicating LC-MS method has been developed to separate all degradation products of the drug on a Hibar-Purospher STAR, C18 (250 × 4.6 mm, 5 μm) column using a mobile phase consisting of 0.1% formic acid and acetonitrile in the gradient mode. BTZ was found to undergo degradation under acidic, basic, neutral hydrolysis and oxidative conditions, whereas it was stable under other conditions. Thirteen degradation products (DP-1-DP-13) were identified using acetonitrile as a co-solvent. Additionally, three (DP-14-DP-16) degradation products were found where methanol was used as a co-solvent. A total of 16 (DP-1-DP-16) degradation products were characterized by liquid chromatography-tandem mass spectrometry (LC-ESI-Q-TOF/MS/MS) and high-resolution mass spectrometry (HRMS). Major degradation products, DP-3, DP-6, DP-9, DP-10, DP-11 and DP-12, formed under oxidation conditions were isolated using preparative HPLC and characterized by 1D and 2D NMR experiments. Furthermore, in vitro cytotoxicity of isolated DPs was tested on normal cell lines such as CHO-K1, HEK-293 and NRK-49F by MTT assays. This study revealed that they were around 2-6 times less toxic as compared with the standard control of the drug and DP-10 showed relatively more toxicity than other isolated DPs against rat kidney cells at 18.20 μM. In silico toxicity studies suggested that BTZ and its DPs can be hepatotoxic and genotoxic resulting in severe toxicity.
- Udutha, Suresh,Borkar, Roshan M.,Shankar,Sony,Jala, Aishwarya,Vamshi Krisna,Kiran Kumar,Misra,Prabhakar,Srinivas
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- Highly Efficient Synthesis of Amino Acids by Amination of Bio-Derived Hydroxy Acids with Ammonia over Ru Supported on N-Doped Carbon Nanotubes
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The amino acids have extensive applications, and their productions from biomass-derived feedstocks are very attractive. In this work, the synthesis of amino acids by amination of bio-derived hydroxy acids with ammonia over different metallic nano-catalysts supported on various supports is studied. It is found that Ru nano-catalysts on the nitrogen-doped carbon nanotubes (Ru/N?CNTs) have an outstanding performance for the reaction. Different hydroxy acids can be catalytically converted into the corresponding amino acids with yields up to 70.0 % under mild conditions, which is higher than those reported. The reasons for the high efficiency of the catalyst are investigated, and the reaction pathway is proposed on the basis of control experiments.
- Xie, Zhenbing,Chen, Bingfeng,Peng, Fangfang,Liu, Mingyang,Liu, Huizhen,Yang, Guanying,Han, Buxing
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- Catalytic amino acid production from biomass-derived intermediates
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Amino acids are the building blocks for protein biosynthesis and find use in myriad industrial applications including in food for humans, in animal feed, and as precursors for bio-based plastics, among others. However, the development of efficient chemical methods to convert abundant and renewable feedstocks into amino acids has been largely unsuccessful to date. To that end, here we report a heterogeneous catalyst that directly transforms lignocellulosic biomass-derived α-hydroxyl acids into α-amino acids, including alanine, leucine, valine, aspartic acid, and phenylalanine in high yields. The reaction follows a dehydrogenation-reductive amination pathway, with dehydrogenation as the rate-determining step. Ruthenium nanoparticles supported on carbon nanotubes (Ru/CNT) exhibit exceptional efficiency compared with catalysts based on other metals, due to the unique, reversible enhancement effect of NH3 on Ru in dehydrogenation. Based on the catalytic system, a two-step chemical process was designed to convert glucose into alanine in 43% yield, comparable with the well-established microbial cultivation process, and therefore, the present strategy enables a route for the production of amino acids from renewable feedstocks. Moreover, a conceptual process design employing membrane distillation to facilitate product purification is proposed and validated. Overall, this study offers a rapid and potentially more efficient chemical method to produce amino acids from woody biomass components.
- Deng, Weiping,Wang, Yunzhu,Zhang, Sui,Gupta, Krishna M.,Hülsey, Max J.,Asakura, Hiroyuki,Liu, Lingmei,Han, Yu,Karp, Eric M.,Beckham, Gregg T.,Dyson, Paul J.,Jiang, Jianwen,Tanaka, Tsunehiro,Wang, Ye,Yan, Ning
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- CYCLOPEPTIDE ALKALOIDS FROM ZIZYPHUS RUGOSA BARK
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The isolation of cyclopeptide alkaloids, nummularine-P, sativanine-H and rugosanine-B, a new 13-membered cyclopeptide alkaloid from the bark of Zizyphus rugosa is reported.The structure of the new alkaloid was elucidated by spectroscopic methods as well as by chemical degradation. Key Word Index-Zizyphus rugusa; Rhamnaceae; alkaloids; nummularine-P; sativanine-H; rugosanine-B.
- Tripathi, Y. C.,Maurya, S. K.,Spingh, V. P.,Pandey, V. B.
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- New diketopiperazine derivatives from a deep-sea-derived Nocardiopsis alba SCSIO 03039
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The strain SCSIO 03039 was isolated from a sediment sample in the Indian Ocean and was characterized as a Nocardiopsis alba species on the basis of its 16S rRNA gene sequence. Seven diketopiperazines (DKPs), including two new DKPs nocazines D (2a) and E (2b), and five known DKPs (1, 3-6), were isolated from N. alba SCSIO 03039, along with two known compounds 2-methoxy-1,4-naphthoquinone (7) and 1-hydroxy-4-methoxy-2-naphthoic acid (8). Their structures were elucidated by mass and NMR spectroscopic analyses. The structure of methoxyneihumicin (1), previously proposed in a conference poster lacking publicly available experimental data, was validated for the first time by detailed NMR analyses and X-ray diffraction study. The two enantiomers nocazines D (2a) and E (2b) were isolated as a mixture. Compounds 3 and 4 were only known as synthetic compounds before. Methoxyneihumicin (1) exhibited in vitro cytotoxicities against MCF-7 and SF-268 with IC 50 values of 4.6 and 12.7 μM, respectively, better than those of 6 (22.0 and 20.6 μM). The other compounds showed less pronounced cytotoxities against three tested human cancer cell lines and no compounds displayed antibacterial activities toward four indicator strains.
- Zhang, Qingbo,Li, Sumei,Chen, Yuchan,Tian, Xinpeng,Zhang, Haibo,Zhang, Guangtao,Zhu, Yiguang,Zhang, Si,Zhang, Weimin,Zhang, Changsheng
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- Stereoselectivity in Reactions of Metal Complexes VII. Asymmetric Synthesis of Amino Acids by Metal Ion-Promoted Transamination
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Enantioselective synthesis of phenylalanine was performed by reacting phenylpyruvic acid with pyridoxamine followed by ketimine-aldimine isomerization of the Schiff base formed catalyzed by an optically active copper(II)-complex.By UV and CD measurements it was shown that the enantiomeric excess strongly depends on the reaction conditions and on the reaction time.In favorable cases it reached values up to 80percent.The selectivity of the reaction is discussed on the basis of possible structures of intermediate mixed ligand complex.
- Bernauer, Klaus,Deschenaux, Robert,Taura, Toshiaki
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- Primordial reductive amination revisited
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Amino acids are formed efficiently by reductive amination of α-keto acids under aqueous, conditions with freshly precipitated FeS or Fe(OH)2 and with NH3, CH3NH2 or (CH3)2NH at pH values near their pKa.
- Huber, Claudia,W?chtersh?user, Günter
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- Electrophilic amination of 2-azadienes
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2-Azadienes 1 bearing a trialkylsilyloxy group on position 3 can be regarded as carboxylic acid synthons. Their cycloadditions with several classes of nitroso compounds have been studied in detail as well as the transformation of the adducts into α-amino acids. The study showed that arylnitroso compounds such as nitrosobenzene reacted with 2-azadienes to give adducts that are potential precursors of α-N-arylamino acids. We have outlined an important limitation to the use of α-chloronitroso compounds. They are not compatible with highly functionalized dienes like 2-azadienes. On the other hand α-cyanonitroso and acylnitroso compounds reacted with azadienes to give adducts which were readily converted into α-amino acid derivatives.
- Gouverneur,Ghosez
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- Nummularine-O, a cyclopeptide alkaloid from Zizyphus nummularia
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In addition to the known peptide alkaloid jubanine-B, a new peptide alkaloid, nummularine-O, has been isolated from the stem bark of Zizyphus nummularia and their structures have been elucidated by chemical and spectroscopic methods.
- Pandey,Dwivedi,Shah,Eckhardt
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- Primordial Amino Acids by Reductive Amination of α-Oxo Acids in Conjunction with the Oxidative Formation of Pyrite
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The theory of an autotrophic origin of life postulates a primordial formation of amino acids by a mild and specific chemical energy source, namely by the reductive amination of α-oxo acids in conjunction with the oxidative formation of pyrite.Here we show experimental proof for this reaction, which involves carbon dioxide as catalyst.
- Hafenbradi, D.,Keller, M.,Waechtershaeuser, G.,Stetter, K. O.
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- Hydrophobic effects on rates and substrate selectivities in polymeric transaminase mimics
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The amination of ketoacids to amino acids by pyridoxamine is greatly accelerated when the pyridoxamine is covalently linked to polyethylenimine carrying N-methyl and N-lauryl groups. Michaelis-Menten kinetics is seen with all substrates, from which the effect of the lauryl groups and the methyl groups can be determined with respect to the strength of binding of the substrate and the rate constant k2 within the complex. The polyamine catalyzes the reaction using acid and base groups, the lauryl groups increase k2 by producing a nonpolar medium in which the reaction occurs, and the lauryl groups promote binding of hydrophobic substrates. The result is that the amination of indolepyruvic acid to produce tryptophan is accelerated by 240000-fold. Copyright
- Liu, Lei,Rozenman, Mary,Breslow, Ronald
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- Autorecycling System for the Synthesis of α-Amino-acids by the Reductive Amination of α-Keto-acids catalysed by 1,5-Dihydro-5-deazaflavin
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An effective autorecycling system for the biomimetic synthesis of α-amino-acids by the reductive amination of α-keto-acids has been achieved for the first time using 10-aryl-5-deazaflavin, ammonium formate, and formic acid; each mole of the 5-deazaflavin catalyses the reduction, by formic acid, of up to 20 moles of the α-imino-acids formed in situ from the α-keto-acids and ammonium formate.
- Yoneda, Fumio,Kuroda, Kazunori
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- BIOSYNTHESIS OF PSILOTIN FROM 2,1'-(14)C,4-(3)H>PHENYLALANINE STUDIED WITH (13)C-NMR
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The 6-phenyl-dihydro-α-pyrone moiety of psilotin is formed from 2,1'-(14)C,-4-(3)H>phenylalanine in the plant Psilotum nudum with retention of all the isotopes.
- Leete, Edward,Muir, Alister,Towers, G. H. Neil
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- KINETIC STUDY OF A Zn2 + -CATALYZED TRANSAMINATION REACTION BETWEEN PYRIDOXAMINE ANALOGS WITH A PYRIDINOPHANE STRUCTURE AND alpha -KETO ACIDS.
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The kinetics of the nonenzymatic transamination reaction from pyridoxamine analogs with a pyridinophane structure to a-keto acids catalyzed by Zn**2** plus were investigated by monitoring the changes in the absorption spectra in methanol. It was found that these reactions obeyed first-order kinetics for the formation of the Zn**2** plus chelate of an aldimine. No appreciable change in the reaction rate was observed when the concentration of the a-keto acid was increased, indicating that the isomerization of the ketimine chelate to the aldimine chelate is the rate-determining step. There was a considerable enhancement of the reaction rate when the molar ratio of the zinc ion to the pyridoxamine analogs was reduced from 1/1 to 0. 5/1.
- Tachibana,Ando,Kuzuhara
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- Catalytic and Electrocatalytic Hydrogenation of Benzylideneazlactone and Benzylidenehydantoin
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The electrocatalytic hydrogenation of benzylidenelactone and 5-benzylidenehydantoin with Raney-nickel proceeded smoothly to afford N-acetylphenylalanine and 5-benzylhydantoin, respectively.In addition, refluxing the electrolyte solution after the electrolysis finally yielded phenylalanine with satisfactory chemical yields and current efficiencies.This electrocatalytic process showed slightly higher reactivity than the ordinary catalytic hydrogenation.
- Matsue, Tomokazu,Yamada, Tsukasa,Takahashi, Hiroko,Osa, Tetsuo
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- Method for the Racemization of Optically Active Amino Acids
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A practical method for the racemization of optically active amino acids has been developed.A wide variety of optically active α-amino acids, including neutral amino acids, acidic amino acids, basic amino acids, and imino acids, could be racemized by heating in a medium of acetic acid at 80-100 deg C for 1 h in the presence of 0.05 molar equiv of an aliphatic or an aromatic aldehyde.The factors influencing the racemization were investigated.Phenylglycine, (p-hydroxyphenyl)glycine, and serine could be racemized without complete dissolution of the optically active isomers.Thus, isolation of the racemic modification was easily achieved by simple filtration of the racemic modification suspended in the reaction mixture.The mechanism of the racemization is discussed.
- Yamada, Shigeki,Hongo, Chikara,Yoshioka, Ryuzo,Chibata, Ichiro
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- Rational engineering ofAcinetobacter tandoiiglutamate dehydrogenase for asymmetric synthesis ofl-homoalanine through biocatalytic cascades
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l-Homoalanine, a useful building block for the synthesis of several chiral drugs, is generally synthesized through biocascades using natural amino acids as cheap starting reactants. However, the addition of expensive external cofactors and the low efficiency of leucine dehydrogenases towards the intermediate 2-ketobutyric acid are two major challenges in industrial applications. Herein, a dual cofactor-dependent glutamate dehydrogenase fromAcinetobacter tandoii(AtGluDH) was identified to help make full use of the intracellular pool of cofactors when using whole-cell catalysis. Through reconstruction of the hydrophobic network between the enzyme and the terminal methyl group of the substrate 2-ketobutyric acid, the strict substrate specificity ofAtGluDH towards α-ketoglutarate was successfully changed, and the activity obtained by the most effective mutant (K76L/T180C) was 17.2 times higher than that of the wild-type protein. A three-enzyme co-expression system was successfully constructed in order to help release the mass transfer restriction. Using 1 Ml-threonine, which is close to the solubility limit, we obtained a 99.9% yield ofl-homoalanine in only 3.5 h without adding external coenzymes to the cascade, giving 99.9% ee and a 29.2 g L?1h?1space-time yield. Additionally, the activities of the engineeredAtGluDH towards some other hydrophobic amino acids were also improved to 1.1-11.2 fold. Therefore, the engineering design of some dual cofactor-dependent GluDHs could not only eliminate the low catalytic activity of unnatural substrates but also enhance the cofactor utilization efficiency of these enzymes in industrial applications.
- Diao, Shiqing,Jiang, Shuiqin,Liu, Yan,Sun, Yangyang,Wang, Hualei,Wang, Liuzhu,Wei, Dongzhi
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p. 4208 - 4215
(2021/06/30)
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- Scope and limitations of reductive amination catalyzed by half-sandwich iridium complexes under mild reaction conditions
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The conversion of aldehydes and ketones to 1° amines could be promoted by half-sandwich iridium complexes using ammonium formate as both the nitrogen and hydride source. To optimize this method for green chemical synthesis, we tested various carbonyl substrates in common polar solvents at physiological temperature (37 °C) and ambient pressure. We found that in methanol, excellent selectivity for the amine over alcohol/amide products could be achieved for a broad assortment of carbonyl-containing compounds. In aqueous media, selective reduction of carbonyls to 1° amines was achieved in the absence of acids. Unfortunately, at Ir catalyst concentrations of 1 mM in water, reductive amination efficiency dropped significantly, which suggest that this catalytic methodology might be not suitable for aqueous applications where very low catalyst concentration is required (e.g., inside living cells).
- Nguyen, Dat P.,Sladek, Rudolph N.,Do, Loi H.
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- Bi-enzymatic Conversion of Cinnamic Acids to 2-Arylethylamines
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The conversion of carboxylic acids, such as acrylic acids, to amines is a transformation that remains challenging in synthetic organic chemistry. Despite the ubiquity of similar moieties in natural metabolic pathways, biocatalytic routes seem to have been overlooked for this purpose. Herein we present the conception and optimisation of a two-enzyme system, allowing the synthesis of β-phenylethylamine derivatives from readily-available ring-substituted cinnamic acids. After characterisation of both parts of the reaction in a two-step approach, a set of conditions allowing the one-pot biotransformation was optimised. This combination of a reversible deaminating and irreversible decarboxylating enzyme, both specific for the amino acid intermediate in tandem, represents a general method by which new strategies for the conversion of carboxylic acids to amines could be designed.
- Weise, Nicholas J.,Thapa, Prasansa,Ahmed, Syed T.,Heath, Rachel S.,Parmeggiani, Fabio,Turner, Nicholas J.,Flitsch, Sabine L.
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p. 995 - 998
(2020/01/21)
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- Synthesis of Unprotected 2-Arylglycines by Transamination of Arylglyoxylic Acids with 2-(2-Chlorophenyl)glycine
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The transamination of α-keto acids with 2-phenylglycine is an effective methodology for directly synthesizing unprotected α-amino acids. However, the synthesis of 2-arylglycines by transamination is problematic because the corresponding products, 2-arylglycines, transaminate the starting arylglyoxylic acids. Herein, we demonstrate the use of commercially available l-2-(2-chlorophenyl)glycine as the nitrogen source in the transamination of arylglyoxylic acids, producing the corresponding 2-arylglycines without interference from the undesired self-transamination process.
- Inada, Haruki,Shibuya, Masatoshi,Yamamoto, Yoshihiko
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p. 11047 - 11059
(2020/10/12)
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- Direct Synthesis of Free α-Amino Acids by Telescoping Three-Step Process from 1,2-Diols
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A practical telescoping three-step process for the syntheses of α-amino acids from the corresponding 1,2-diols has been developed. This process enables the direct synthesis of free α-amino acids without any protection/deprotection step. This method was also effective for the preparation of a 15N-labeled α-amino acid. 1,2-Diols bearing α,β-unsaturated ester moieties afforded bicyclic α-amino acids through intramolecular [3 + 2] cycloadditions. A preliminary study suggests that the resultant α-amino acids are resolvable by aminoacylases with almost complete selectivity.
- Inada, Haruki,Shibuya, Masatoshi,Yamamoto, Yoshihiko
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supporting information
p. 709 - 713
(2019/01/25)
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- Electrosynthesis of amino acids from biomass-derivable acids on titanium dioxide
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Seven amino acids were electrochemically synthesized from biomass-derivable α-keto acids and NH2OH with faradaic efficiencies (FEs) of 77-99% using an earth-Abundant TiO2 catalyst. Furthermore, we newly constructed a flow-Type electrochemical reactor, named a "polymer electrolyte amino acid electrosynthesis cell", and achieved continuous production of alanine with an FE of 77%.
- Fukushima, Takashi,Yamauchi, Miho
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supporting information
p. 14721 - 14724
(2019/12/24)
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- Tertiary-butoxycarbonyl (Boc) – A strategic group for N-protection/deprotection in the synthesis of various natural/unnatural N-unprotected aminoacid cyanomethyl esters
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A number of cyanomethyl esters of natural/unnatural aminoacids with un-protected amino functionality were synthesized because of their synthetic and medicinal importance. Critical N-Boc deprotection methods in the presence of labile (hydrolytic sensitivity) cyanomethyl functionality were screened thoroughly and it was found that readily available 4M HCl in 1,4-dioxane solution (2–4 equiv); acetonitrile, 0 °C, 2–4 h was a suitable condition. This condition was generalized and successfully applied to a variety of alkyl, alkynyl, aryl, heteroaryl, benzyl, azido, spiro amino acid cyanomethylesters irrespective of the nature of the amine (primary or secondary) and the distance between the amine and ester group to achieve final deprotected amino esters with high yield, and purity compared to other commonly known N-protecting groups (Cbz, Fmoc, Ac, Bn, Bz etc.). It was also demonstrated that N-Boc protected aminoacid cyanomethylesters are stable enough to carry out further functionalization compared to N-unprotected counterparts.
- Karmakar, Ananta,Basha, Mushkin,Venkatesh Babu,Botlagunta, Murali,Malik, Noormohamed Abdul,Rampulla, Richard,Mathur, Arvind,Gupta, Arun Kumar
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p. 4267 - 4271
(2018/11/03)
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- One-Pot Enzymatic Synthesis of d-Arylalanines Using Phenylalanine Ammonia Lyase and l-Amino Acid Deaminase
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The phenylalanine ammonia-lyase (AvPAL) from Anabaena variabilis catalyzes the amination of substituent trans-cinnamic acid (t-CA) to produce racemic d,l-enantiomer arylalanine mixture owing to its low stereoselectivity. To produce high optically pure d-arylalanine, a modified AvPAL with high d-selectivity is expected. Based on the analyses of catalytic mechanism and structure, the Asn347 residue in the active site was proposed to control stereoselectivity. Therefore, Asn347 was mutated to construct mutant AvPAL-N347A, the stereoselectivity of AvPAL-N347A for d-enantiomer arylalanine was 2.3-fold higher than that of wild-type AvPAL (WtPAL). Furthermore, the residual l-enantiomer product in reaction solution could be converted into the d-enantiomer product through stereoselective oxidation by PmLAAD and nonselective reduction by reducing agent NH3BH3. At optimal conditions, the conversion rate of t-CA and optical purity (enantiomeric excess (eeD)) of d-phenylalanine reached 82% and exceeded 99%, respectively. The two enzymes displayed activity toward a broad range of substrate and could be used to efficiently synthesize d-arylalanine with different groups on the phenyl ring. Among these d-arylalanines, the yield of m-nitro-d-phenylalanine was highest and reached 96%, and the eeD exceeded 99%. This one-pot synthesis using AvPAL and PmLAAD has prospects for industrial application.
- Zhu, Longbao,Feng, Guoqiang,Ge, Fei,Song, Ping,Wang, Taotao,Liu, Yi,Tao, Yugui,Zhou, Zhemin
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- Organocatalytic Enantioselective Addition of α-Aminoalkyl Radicals to Isoquinolines
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With a dual organocatalytic system involving a chiral phosphoric acid and a dicyanopyrazine-derived chromophore (DPZ) photosensitizer and under the irradiation with visible light, an enantioselective Minisci-type addition of α-amino acid-derived redox-active esters (RAEs) to isoquinolines has been developed. A variety of prochiral α-aminoalkyl radicals generated from RAEs were successfully introduced on isoquinolines, providing a range of valuable α-isoquinoline-substituted chiral secondary amines in high yields with good to excellent enantioselectivities.
- Liu, Xiangyuan,Liu, Yang,Chai, Guobi,Qiao, Baokun,Zhao, Xiaowei,Jiang, Zhiyong
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supporting information
p. 6298 - 6301
(2018/10/09)
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- PROCESS FOR THE RACEMIZATION OF ALPHA-AMINO ACIDS
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According to the present invention, a method is provided wherein a basic aqueous phase containing an optically active α-amino acid is brought into contact with an organic phase containing a racemisation catalyst in the form of a copper metal complex of copper ions and an α-amino acid and salicylaldehyde, in the presence of a phase transition catalyst, thereby subjecting the optically active α-amino acid to racemisation. In the α-amino acid racemisation method according to the present invention, the reaction conditions are mild and thus there is little α-amino acid breakdown and the yield is high, the racemisation catalyst can be reused, the α-amino acid resulting from the racemisation can easily be isolated and purified, and the racemisation method can be implemented in volume such that the invention is economic.
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Paragraph 0056-0057
(2016/08/29)
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- Telescopic one-pot condensation-hydroamination strategy for the synthesis of optically pure L-phenylalanines from benzaldehydes
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A chemo-enzymatic telescopic approach was designed for the synthesis of L-arylalanines in high yield and optical purity, starting from commercially available and inexpensive substituted benzaldehydes. The method exploits a chemical Knoevenagel–Doebner condensation (optimised to give complete conversions in a short reaction time, employing microwave irradiation) and a biocatalytic phenylalanine ammonia lyase mediated hydroamination (for the stereoselective addition of ammonia). The two reactions can be run sequentially in one pot, bringing together the advantages of chemical and biological catalysis. The preparative applicability was demonstrated with the synthesis of five L-dihalophenylalanines (71–84% yield, 98–99% ee) of relevance as molecular probes, for medicinal chemistry and for the synthesis of pharmaceutical ingredients.
- Parmeggiani, Fabio,Ahmed, Syed T.,Weise, Nicholas J.,Turner, Nicholas J.
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p. 7256 - 7262
(2016/10/26)
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- Phenylalanine ammonia lyase catalyzed synthesis of amino acids by an MIO-cofactor independent pathway
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Phenylalanine ammonia lyases (PALs) belong to a family of 4-methylideneimidazole-5-one (MIO) cofactor dependent enzymes which are responsible for the conversion of L-phenylalanine into trans-cinnamic acid in eukaryotic and prokaryotic organisms. Under conditions of high ammonia concentration, this deamination reaction is reversible and hence there is considerable interest in the development of PALs as biocatalysts for the enantioselective synthesis of non-natural amino acids. Herein the discovery of a previously unobserved competing MIO-independent reaction pathway, which proceeds in a non-stereoselective manner and results in the generation of both L- and D-phenylalanine derivatives, is described. The mechanism of the MIO-independent pathway is explored through isotopic-labeling studies and mutagenesis of key active-site residues. The results obtained are consistent with amino acid deamination occurring by a stepwise E1cB elimination mechanism. All manner of things: A competing MIO-independent (MIO=4-methylideneimidazole-5-one) reaction pathway has been identified for phenylalanine ammonia lyases (PALs), which proceeds in a non-stereoselective manner, resulting in the generation of D-phenylalanine derivatives. The mechanism of D-amino acid formation is explored through isotopic-labeling studies and mutagenesis of key active-site residues.
- Lovelock, Sarah L.,Lloyd, Richard C.,Turner, Nicholas J.
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p. 4652 - 4656
(2014/05/20)
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- Meteorites as catalysts for prebiotic chemistry
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From outer space: Twelve meteorite specimens, representative of their major classes, catalyse the synthesis of nucleobases, carboxylic acids, aminoacids and low-molecular-weight compounds from formamide (see figure). Different chemical pathways are identified, the yields are high for a prebiotic process and the products come in rich and composite panels.
- Saladino, Raffaele,Botta, Giorgia,Delfino, Michela,Di Mauro, Ernesto
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p. 16916 - 16922
(2014/01/06)
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- Biocatalytic asymmetric synthesis of unnatural amino acids through the cascade transfer of amino groups from primary amines onto keto acids
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Flee to the hills: An unfavorable equilibrium in the amino group transfer between amino acids and keto acids catalyzed by α-transaminases was successfully overcome by coupling with a ω-transaminase reaction as an equilibrium shifter, leading to efficient asymmetric synthesis of diverse unnatural amino acids, including L-tert-leucine and D-phenylglycine. Copyright
- Park, Eul-Soo,Dong, Joo-Young,Shin, Jong-Shik
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p. 3538 - 3542
(2014/01/06)
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- Two new 14-membered cyclopeptide alkaloids from Zizyphus xylopyra
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The phytochemical investigation of the bark of Zizyphus xylopyra resulted in the isolation of two new 14-membered ring cyclopeptide alkaloids, xylopyrine-G and xylopyrine H. Their structures have been established by chemical and spectral evidences.
- Pandey, Manoj B.,Singh, Sarita,Malhotra, Meenakshi,Pandey, Vidya B.,Singh, Tryambak D.
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experimental part
p. 836 - 841
(2012/10/07)
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- Hapalocyclamide: A novel phytotoxic hexapeptide of the cyanobacterium Hapalosiphon sp.
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Hapalocyclamide, a novel oxazole-, thiazole- and thiazoline-containing cyclic hexapeptide, was isolated from the terrestrial cyanobacterium Hapalosiphon sp., and which showed phytotoxic activity on lettuce seedling growth. The gross structure of hapalocyclamide was established from spectroscopic data and chemical degradation. The absolute stereochemistry was determined by Marfey's analysis. Hapalocyclamide was established as cyclo-thiazole-l-alanine-oxazole-d-alanine-d-thiazoline-d-phenylalanine.
- Koodkaew, Intira,Matsuyama, Shigeru,Sunohara, Yukari,Matsumoto, Hiroshi
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experimental part
p. 977 - 979
(2012/03/26)
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- Enhanced reduction of C-N multiple bonds using sodium borohydride and an amorphous nickel catalyst
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Amorphous nickel powder (Ni0) was utilised as a catalyst under mild, aqueous, basic conditions for enhancing the sodium borohydride-mediated reduction of C-N multiple bonds such as oximes, imines, hydrazones and nitriles to produce the corresponding amines in good to excellent yields.
- Liu, Shouxin,Yang, Yihua,Zhen, Xiaoli,Li, Junzhang,He, Huimin,Feng, Juan,Whiting, Andrew
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experimental part
p. 663 - 670
(2012/01/15)
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- Convenient method for reduction of C-N double bonds in oximes, imines, and hydrazones using sodium Borohydride-Raney ni system
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(Chemical Equation Presented) A practical method has been developed for reduction of C-N double bond in oximes, imines, and hydrazones with sodium borohydride catalyzed by Raney Ni. The reactions were carried out in basic aqueous solution, and the desired products were obtained in moderate yields after a simple procedure. This method can be applied to synthesize simpler aliphatic or aromatic amines and its analogs. Copyright Taylor & Francis Group, LLC.
- Yang, Yihua,Liu, Shouxin,Li, Junzhang,Tian, Xia,Zhen, Xiaoli,Han, Jianrong
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experimental part
p. 2540 - 2554
(2012/07/27)
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- Enhanced conversion of racemic α-arylalanines to (R)-β- arylalanines by coupled racemase/aminomutase catalysis
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(Graph Presented) The Taxus phenylalanine aminomutase (PAM) enzyme converts several (S)-α-arylalanines to their corresponding (R)-β- arylalanines. After incubating various racemic substrateswith 100 μg of PAM for 20 h at 31°C, each (S)-α-arylalanine was enantioselectively isomerized to its corresponding (R)-β-product. With racemic starting materials, the ratio of (R)-β-arylalanine product to the (S)-α-substrate ranged between 0.4 and 1.8, and the remaining nonproductive (R)-α-arylalanine became enriched. To utilize the (R)-α-isomer, the catalysis of a promiscuous alanine racemase from Pseudomonas putida (KT2440) was coupled with that of PAM to increase the production of enantiopure (R)-β-arylalanines from racemic α-arylalanine substrates. The inclusion of a biocatalytic racemization along with the PAM-catalyzed reactionmoderately increased the overall reaction yield of enantiopure β-arylalanines between 4% and 19% (depending on the arylalanine), which corresponded to as much as a 63% increase compared to the turnover with the aminomutase reaction alone. The use of these biocatalysts, in tandem, could potentially find application in the production of chiral β-arylalanine building blocks, particularly, as refinements to the process are made that increase reaction flux, such as by selectively removing the desired (R)-β-arylalanine product from the reaction mixture. 2009 American Chemical Society.
- Cox, Brad M.,Bilsborrow, Joshua B.,Walker, Kevin D.
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experimental part
p. 6953 - 6959
(2009/12/25)
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- High rates and substrate selectivities in water by polyvinylimidazoles as transaminase enzyme mimics with hydrophobically bound pyridoxamine derivatives as coenzyme mimics
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(Chemical Equation Presented) Free-radical polymers of 4-vinylimidazole and copolymers with 1-dodecyl-4-vinylimidazole were used as enzyme mimics to transaminate pyruvic acid to alanine, phenylpyruvic acid to phenylalanine, and indole-3-pyruvic acid to tryptophan in water at pH 7.5 and 20 °C using pyridoxamines carrying hydrophobic side chains as coenzyme mimics. The best enzyme mimic accelerated the transamination of indole-3-pyruvic acid by a factor of 4 million relative to the rate without the polymer, a higher rate ratio than we had previously achieved with a polyaziridine-based enzyme mimic. The properties of various polyvinylimidazoles were compared, including those prepared with the RAFT modification of the polymerization process.
- Skouta, Rachid,Wei, Sujun,Breslow, Ronald
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supporting information; experimental part
p. 15604 - 15605
(2010/01/30)
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- Microwave-assisted synthesis of unnatural amino acids
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Microwave irradiation has been proven to be a useful tool in the rapid assembly of racemic unnatural amino acids in only two steps. Additional benefits of this methodology are the commercial availability of the inexpensive starting materials and the high yields and high purities of the final amino acid products.
- Young, Douglas D.,Torres-Kolbus, Jessica,Deiters, Alexander
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experimental part
p. 5478 - 5480
(2009/05/30)
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- Synthesis and catalytic properties of diverse chiral polyamines
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Chiral polyamines can be utilized for a variety of potential applications, ranging from asymmetric catalysis to nonviral gene delivery systems for DNA and RNA. They can also be utilized to solubilize carbon nanotubes. Thus, methods for the straightforward synthesis of chiral polyamines are needed. We present herein two synthetic strategies for accessing chiral polyamines. The potential of these chiral amines to catalyze two organic reactions with a high degree of chiral induction was also explored.
- Levine, Mindy,Kenesky, Craig S.,Zheng, Shengping,Quinn, Jordan,Breslow, Ronald
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p. 5746 - 5750
(2008/12/22)
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- Compositions, kits, and methods relating to the human FEZ1 gene, a novel tumor suppressor gene
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The invention relates to isolated polynucleotides homologous with a portion of one strand of the human tumor suppressor gene, FEZ1, and to the tumor suppressor protein encoded thereby, Fez1. The polynucleotides are useful, for example, as probes, primers, portions of expression vectors, and the like. The invention also includes diagnostic, therapeutic, cell proliferation enhancement, and screening methods which involve these polynucleotides and protein. The invention further includes kits useful for performing the methods of the invention.
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- Efficient amidation from carboxylic acids and azides via selenocarboxylates: Application to the coupling of amino acids and peptides with azides
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(Chemical Equation Presented) A facile one-pot procedure for the coupling of carboxylic acid and azide via selenocarboxylate and selenatriazoline has been developed and successfully applied to the coupling of amino acids and peptides with azides. Selenocarboxylates are readily prepared by the reaction of the activated carboxylic acids with LiAlHSeH under mild conditions. The Selenocarboxylates formed in situ are used to react directly with azides to form the corresponding amides via a selenatriazoline intermediate. Excellent yields were obtained for electron-deficient azides, and moderate to good yields were obtained for electron-rich azides. The selenocarboxylate/azide amidation reaction is clean and chemoselective. It provides an attractive alternative method to the conventional acylation of amines when an amide bond needs to be formed without going through an amine intermediate.
- Wu, Xinghua,Hu, Longqin
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p. 765 - 774
(2007/10/03)
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- DISUBSTITUTED CUCURBITURIL-BONDED SILICA GEL
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A disubstituted cucurbituril-bonded silica gel and its use are provided. The disubstituted cu-curbituril-bonded silica gel is useful for removal of air pollutants or water contaminants, and separation and purification of biological, organic, inorganic, or ionic substances.
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Page/Page column 19
(2008/06/13)
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- Method for producing amines by homogeneously catalyzed reductive amination of carbonyl compounds
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The invention relates to the preparation of chiral or achiral amines by reaction of aldehydes or ketones with ammonia or primary or secondary amines in the presence of hydrogen and in the presence of homogeneous metal catalysts under mild conditions. Metal catalysts which can be used are complexes of late transition metals with chiral or achiral phosphorus-containing ligands.
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Page/Page column 14-15
(2010/02/11)
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- T-CELL SELECTIVE INTERLEUKIN-4 AGONISTS
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The invention is directed to human IL-4 muteins numbered in accordance with wild-type IL-4 having T-cell activating activity, but having reduced endothelial cell activating activity. In particular, the invention is related to human IL-4 muteins wherein the surface-exposed residues of the D helix of the wild-type IL-4 are mutated whereby the resulting mutein causes T-cell proliferation, and causes reduced IL-6 secretion from HUVECs, relative to wild-type IL-4. This invention realizes a less toxic IL-4 mutant that allows greater therapeutic use of this interleukin. Further, the invention is directed to IL-4 muteins having single, double and triple mutations represented by the designators R121A, R121D, R121E, R121F, R121H, R121I, R121K, R121N, R121P, R121T, R121W; Y124A, Y124Q, Y124R, Y124S, Y124T; Y124A/S125A, T13D/R121E; and R121T/E122F/Y124Q, when numbered in accordance with wild-type IL-4 (His=1). The invention also includes polynucleotides coding for the muteins of the invention, vectors containing the polynucleotides, transformed host cells, pharmaceutical compositions comprising the muteins, and therapeutic methods of treatment.
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- CONJUGATES OF TRANSPORTER PEPTIDES AND NUCLEIC ACID ANALOGS, AND THEIR USE
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Constructs of peptides and nucleic acid analogs conjugated together for transport across a lipid membrane and for delivery into interactive contact with intracellular polynucleotides are disclosed. Transport is effected through at least the exterior membrane of a cell, and most likely also through the walls of subcellular structures separated from the cytosol by lipid membranes, including the nucleus, mitochondria, ribosomes, etc. Peptide nucleic acid (PNA) analog sequences conjugated through a labile disulfide bond to transporting peptides, are intracellulary cleaved, and target mRNA (antigene) or dsDNA (antisense).
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- Compositions and methods for promoting internalization and degradation of urokinase-type plasminogen activator
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The invention includes compositions and methods for promoting internalization and degradation of urokinase-type plasminogen activator.
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- pH-Dependent Chemoselective Synthesis of α-Amino Acids. Reductive Amination of α-Keto Acids with Ammonia Catalyzed by Acid-Stable Iridium Hydride Complexes in Water
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An acid-stable hydride complex [Cp*IrIII(bpy)H]+ {1, Cp* = η5-C5Me5, bpy = 2,2′-bipyridine} serves as the active catalyst for the highly chemoselective synthesis of α-amino acids by reductive aminatio
- Ogo, Seiji,Uehara, Keiji,Abura, Tsutomu,Fukuzumi, Shunichi
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p. 3020 - 3021
(2007/10/03)
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- (1 -> 3, 1 -> 4)-beta-glucanase of enhanced stability
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A modified cereal (1→3,1→4)-β-glucanase is produced by the method of single point substitution in a native cereal (1→3,1→4)-β-glucanase enzyme, whereby the substitution: a) maintains enzyme specificity by conserving the active site groove of the native cereal (1→3,1→4)-β-glucanase enzyme; and b) effects increased thermostability over the native cereal (1→3,1→4)-β-glucanase enzyme by: i) replacing glycine by proline or alanine in helices of the cereal (1→3,1→4)-β-glucanase enzyme, in order to stiffen the enzyme amino acid chain and reduce entropy of the unfolded enzyme; ii) attaching negatively charged residues to N-termini of helices in the native cereal (1→3,1→4)-β-glucanase enzyme; iii) introducing ion pairs into the native cereal (1→3,1→4)-β-glucanase enzyme, to increase binding energy in the folded enzyme; iv) replacing lysine by arginine in the cereal (1→3,1→4)-β-glucanase enzyme, and thereby preventing lysine glycation and increasing hydrogen bonding with other parts of the enzyme; v) replacing, by glycine, an amino acid in the native cereal (1→3,1→4)-β-glucanase enzyme in which the main chain torsion angle about the N and Cα atoms is greater than 0°; or vi) creating cysteine pairs in the native cereal (1→3,1→4)-β-glucanase enzyme which can form disulphide bonds across the C and N terminals.
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- Compounds that bind HER2
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The invention provides novel compounds which bind to the human erbB2 gene product (ErbB2, also known as HER2, or c-ErbB-2). In particular aspects, the invention provides for the treatment of disorders characterized by the overexpression of ErbB2 utilizing the novel compounds of the invention. The invention also provides pharmaceutical compositions comprising the novel compounds as well as for their use in research, diagnostic, therapeutic, and prophylactic methods.
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- Phenylalanine derivatives
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Phenylalanine derivatives of the following formulae and analogues thereof have an antagonistic activity to α4 integrin. They are used as therapeutic agents for various diseases concerning α4 integrin.
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- Method for producing carboxylic acid by alcohol oxidation
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The invention relates to a method for oxidizing primary amino alcohols, primary or secondary alkenols or alkinols into the corresponding acids or ketones. According to said method, a primary amino alcohol or a primary or secondary alkenol or alkinol is oxidized in the form of a substrate, in the presence of an equimolar quantity of periodate or a molar excess thereof in relation to the alcoholic hydroxy groups and catalytic quantities of dichromate or CrO3 and in the presence of an acid in water, a water/solvent mixture or a solvent at a temperature of ?20 ° C. to +50 ° C., to produce the corresponding acid or the corresponding ketone.
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- Carbohydrate epitope mimic compounds and uses thereof
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This invention provides carbohydrate epitope mimic compounds, particularly peptides, and analogs and variants thereof. In particular, the compounds and peptides of the present invention mimic the carbohydrate epitope GlcAβ1→3Galβ1→4GlcNAc or sulfate -3GlcAβ1→3Galβ1→4GlcNAc, or the L2/HNK1 carbohydrate epitope. This invention provides an isolated peptide comprising an amino acid sequence of a carbohydrate epitope mimic peptide in which the amino acid sequence is set forth in any of SEQ ID NOS: 1-8, 27-38, 39, 40 and 41, including variants, analogs and active fragments thereof. The invention further provides an isolated nucleic acid encoding a peptide comprising an amino acid sequence of a carbohydrate epitope mimic peptide. This invention provides pharmaceutical compositions and diagnostic and therapeutic methods of use of the isolated polypeptides and nucleic acids, particularly in modulating or mediating cell-cell adhesion and viral infection and the processes and events mediated thereby. Assays for compounds which mimic, alter or inactivate the polypeptides of the present invention for use in therapy are also provided.
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- Inhibition of BEHAB cleavage and primary central nervous system (CNS) tumors
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The present invention relates to primary CNS tumors and provides useful compositions and methods for reducing tumor volume and increasing the length of survival in mammals with primary CNS tumors, thereby providing a treatment for primary CNS tumors. The invention also relates to methods of identifying compounds for reducing tumor volume and increasing animal survival, which therefore relate to treating primary CNS tumors.
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- Compositions, methods, and kits relating to resistin-like molecules
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The invention relates to novel nucleic acids encoding a mammalian resistin-like molecule (RELM), and proteins encoded thereby, whose expression is increased in certain diseases, disorders, or conditions, including, but not limited to, intestinal (e.g., colonic) tumors. The invention further relates to methods of treating and detecting irritable bowel disease, inflammatory bowel disease, familial adenomatous polyposis, diabetes, insulin resistance, obesity, Syndrome X, and glucose metabolism disorders, colon cancer, breast cancer, and tongue cancer, comprising modulating or detecting RELM expression and/or production and activity of RELM polypeptide, wherein RELM encompasses resistin-like molecule α and resistin-like molecule β.
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- Mammalian prestin polynucleotides
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The invention relates to mammalian prestin protein, which has been discovered to be the mammalian cochlear outer hair cell motor, and to polynucleotides encoding prestin. Full length gerbil prestin and its cDNA are described, full length murine prestin and its cDNA are described, and a partial sequence of human prestin and its chromosomal location are described.
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- 20(S) camptothecin glycoconjugates
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The present invention relates to glycoconjugates of 20(S)-camptothecin, in which a 3-O-methylated β-L-fucose unit is linked to the 20-hydroxyl group of a camptothecin derivative via a thiourea-modified peptide spacer. The invention furthermore relates to processes for the preparation of the compounds according to the invention and to their use as medicaments, in particular in connection with oncoses.
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- Monoclonal antibody against human telomerase catalytic subunit
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The present invention provides a monoclonal antibody which can specifically and efficiently recognize hTERT protein; which is the catalytic subunit of telomerase, and provides a human chimeric antibody, a CDR grafted antibody, a single chain antibody, and a disulfide stabilized antibody each containing the monoclonal antibody. In addition, the present invention provides a method for detecting/quantitating hTERT protein using these antibodies, and provides diagnosis method, diagnosis agent, and therapeutic agent, for diseases, such as cancer, in which telomerase is involved using these bodies.
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- Nasal pharmaceutical compositions containing a NK-2 antagonist
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Pharmaceutical compositions suitable for the nasal administration containing:iii) an NK-2 antagonist or its pharmaceutically acceptable saltsiv) a polyacrylic acid and/or its derivatives possibly in combination with other excipients used in the preparation of pharmaceutical composition for nasal administration are described.
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- N1 modified glycopeptides
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Described herein are N′-acylated derivatives of desleucylA82846B. The compounds are useful as antibacterial agents.
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- Solid phase reduction of oxazolones using BER-Ni2B-A simple synthesis of N-benzoylphenylalanines
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Borohydride exchange resin (BER)-Ni2B is successfully used as a reagent for the solid phase reduction of the C-4 exocyclic double bond of oxazolones to give the N-benzoylphenylalanines and hence the corresponding amino acids.
- Sikdar, Atul P.,Chetri, Ajoy B.,Das, Pranab J.
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p. 2878 - 2881
(2007/10/03)
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- DNA ENCODING THE HUMAN SYNAPSIN III GENE AND USES THEREOF
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A new synapsin protein, designated synapsin III, its amino acid sequence, and its human gene have been isolated and characterized. Furthermore, isoforms of synapsin III, e.g., synapsin IIIa, IIIb and IIIc, and have isolated and characterized, and cDNA encoding these isoforms has also been isolated and characterized. The synapsin III gene is located on human chromosome 22, in the vicinity of a region previously identified as a susceptibility locus for schizophrenia. The information and experimental tools provided by this discovery can be used to generate new therapeutic agents or diagnostic assays for this new protein, its associated mRNA or its associated genomic DNA. Due to its role in neurotransmission and synaptogenesis, isoforms of synapsin III are associated with the symptoms of psychiatric diseases, especially schizophrenia.
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