- A fundamental study of amadori rearrangement products in reducing sugar-amino acid model system by electrospray ionization mass spectrometry and computation
-
It is crucial to characterize Amadori rearrangement products (ARPs) formed in the early stage of Maillard reaction, one of the most important modifications in food science. We setup a reaction model system using six selected amino acids (arginine, asparagines, glutamine, histamine, lysine and tryptophan) and their N-terminal acetylated forms with different reducing sugars for a fundamental study of Amadori rearrangement products. The effects on forming Amadori rearrangement products were studied by using electrospray ionization mass spectrometry (ESI-MS). The reaction rate was affected by reaction temperature, reaction time, property of sugars and amino acids and the fragmentation mechanism of Amadori rearrangement products was illustrated by tandem MS (MS2) with collision-induced dissociation. The proposed fragmentation mechanism of Amadori rearrangement products in MS2 was provided based on MS2 data and it was supported by their computational data of density functional theory (DFT) at the B3LYP/6-31++G(d,p) level.
- Zhang,Ruan,Wang,Ruan,Shao,Aalhus,Juárez
-
-
Read Online
- Reaction of vitamin e compounds with n-nitrosated tryptophan derivatives and its analytical use
-
We recently showed that nitrosated tryptophan residues may act as endogenous nitric oxide storage compounds. Here, a novel reaction of nitrosotryptophan derivatives is described, in the form of the release of nitric oxide from N-nitrosotryptophan derivatives initiated either by a-tocopherol or by its water-soluble form trolox. α-Tocopherol and trolox were found to release stoichiometric amounts of nitric oxide from N-acetylN-nitrosotryptophan as well as from the nitrosotryptophan residue in albumin. The reaction proceeds both in water and in lipophilic solution and reconstitutes the indole moiety of the tryptophan molecule quantitatively. During this reaction, α-tocopherol- and trolox-derived phenoxyl-type radicals were identified as intermediates by ESR spectrometry. The chemical mechanism of the NO-releasing process was established. Since S-nitrosothiols donot react under the applied conditions, it is suggested that the trolox-dependent release of nitric oxide may be utilizable for the detection of N-nitrosotryptophan residues in biological samples. Furthermore, as N-nitrosotryptophan derivatives do not undergo spontaneous decay in lipophilic environments, vitamin E may have the so far unrecognized function of preventing the accumulation of N-nitrosotryptophan residues to toxic concentrations in biological systems.
- Mueller, Karsten,Korth, Hans-Gert,De Groot, Herbert,Kirsch, Michael
-
-
Read Online
- Comparison of HNO reactivity with tryptophan and cysteine in small peptides
-
Recent discoveries of important pharmacological properties have drawn attention to the reactivity of HNO (azanone, nitroxyl) with biologically relevant substrates. Apart from its role in thiol oxidation, HNO has been reported to have nitrosative properties, for example, with tryptophan resulting in N-nitrosotryptophan formation. We have investigated the reactivity of HNO with tryptophan and small peptides containing either tryptophan or both a tryptophan and a cysteine residue. Our results point to the more reactive nature of cysteine towards HNO compared with tryptophan.
- Keceli, Gizem,Moore, Cathy D.,Toscano, John P.
-
-
Read Online
- The biosynthetic pathway of crucifer phytoalexins and phytoanticipins: De novo incorporation of deuterated tryptophans and quasi-natural compounds
-
Although several biosynthetic intermediates in pathways to cruciferous phytoalexins and phytoanticipins are common, questions regarding the introduction of substituents at N-1 of the indole moiety remain unanswered. Toward this end, we investigated the potential incorporations of several perdeuterated d- and l-1′-methoxytryptophans, d- and l-tryptophans and other indol-3-yl derivatives into pertinent phytoalexins and phytoanticipins (indolyl glucosinolates) produced in rutabaga (Brassica napus L. ssp. rapifera) roots. In addition, we probed the potential transformations of quasi-natural compounds, these being analogues of biosynthetic intermediates that might lead to "quasi-natural" products (products similar to natural products but not produced under natural conditions). No detectable incorporations of deuterium labeled 1′-methoxytryptophans into phytoalexins or glucobrassicin were detected. l-tryptophan was incorporated in a higher percentage than d-tryptophan into both phytoalexins and phytoanticipins. However, in the case of the phytoalexin rapalexin A, both d- and l-tryptophan were incorporated to the same extent. Furthermore, the transformations of both 1′-methylindolyl-3′-acetaldoxime and 1′-methylindolyl-3′-acetothiohydroxamic acid (quasi-natural products) into 1′-methylglucobrassicin but not into phytoalexins suggested that post-aldoxime enzymes in the biosynthetic pathway of indolyl glucosinolates are not substrate-specific. Hence, it would appear that the 1-methoxy substituent of the indole moiety is introduced downstream from tryptophan and that the post-aldoxime enzymes of the glucosinolate pathway are different from the enzymes of the phytoalexin pathway. A higher substrate specificity of some enzymes of the phytoalexin pathway might explain the relatively lower structural diversity among phytoalexins than among glucosinolates.
- Pedras, M. Soledade C.,Okinyo-Owiti, Denis P.,Thoms, Ken,Adio, Adewale M.
-
-
Read Online
- Kinetics and Mechanism of the Nitrosation of N-Acetyltryptophan and of the Denitrosation of N-Acetyl-N1-nitrosotryptophan
-
Both the formation and the denitrosation of N-acetyl-N1-nitrosotryptophan have been studied kinetically in aqueous solution at 25 deg C at acidities between 1M-HClO4 and pH 4.A value of 850 l mol-1 has been obtained for the equilibrium constant for the formation of N-acetyl-N1-nitrosotryptophan.At acidities (+>) greater than 0.1M the rate constants for both nitrosation and denitrosation increase linearly with the concentration of acid, and the reaction rates are unaffected by the addition of nucleophiles (Br- and SCN-).The results are consistent with a mechanism for nitrosation where the rate-limiting step is the proton transfer from the protonated N-nitroso species to the medium.For denitrosation the corresponding protonation of the nitrosamine is rate-limiting.These conclusions are confirmed by the results obtained when the reactions are carried out in heavy water.However, in the pH range 1-4 the rates of both nitrosation and denitrosation are independent of the acidity of the medium and are again unaffected by the presence of nucleophiles or buffers.It is suggested that in this region nitrosation occurs at C-3.This is followed by deprotonation and an internal NO migration from C to N which is rate-limiting.This mechanism also accounts for earlier results on the denitrosation reaction at even lower acidities (pH 4-7), where acid catalysis and nucleophilic catalysis are found.Results of experiments in heavy water are compatible with this mechanism.
- Castro, Albino,Iglesias, Emilia,Leis, J. Ramon,Pena, M. Elena,Tato, Jose Vazquez,Williams, D. Lyn H.
-
-
Read Online
- Hydrogen/deuterium exchange of cross-linkable α-amino acid derivatives in deuterated triflic acid
-
In this paper we report here a hydrogen/deuterium exchange (H/D exchange) of cross-linkable α-amino acid derivatives with deuterated trifluoromethanesulfonic acid (TfOD). H/D exchange with TfOD was easily applied to o-catechol containing phenylalanine (DOPA) within an hour. A partial H/D exchange was observed for trifluoromethyldiazirinyl (TFMD) phenylalanine derivatives. N-Acetyl-protected natural aromatic α-amino acids (Tyr and Trp) were more effective in H/D exchange than unprotected ones. The N-acetylated TFMD phenylalanine derivative afforded slightly higher H/D exchange than unprotected derivatives. An effective post-deuteration method for cross-linkable α-amino acid derivatives will be useful for the analysis of biological functions of bioactive peptides and proteins by mass spectrometry.
- Wang, Lei,Murai, Yuta,Yoshida, Takuma,Okamoto, Masashi,Masuda, Katsuyoshi,Sakihama, Yasuko,Hashidoko, Yasuyuki,Hatanaka, Yasumaru,Hashimoto, Makoto
-
-
Read Online
- Crosslinking of imprinted proteases to maintain a tailor-made substrate selectivity in aqueous solutions
-
A covalent method to keep imprinted properties of proteins stable in aqueous as well as in organic environment is described. To stabilize the ligand induced acceptance for d-configured substrates by α-chymotrypsin or subtilisin Carlsberg, each protein was first vinylated by acylation with itaconic anhydride. Then, the tailoring of the derivatized proteins by precipitation in the presence of N-acetyl-D-tryptophan from an aqueous medium with 1-propanol, and the subsequent crosslinking of the enzyme preparations with ethylene glycol dimethacrylate in cyclohexane was carried out. The crosslinked imprinted proteins (CLIPs) obtained catalyzed the hydrolysis of N-acetyl-D-tryptophan ethyl ester in phosphate buffer and the corresponding back reaction in cyclohexane, respectively. The repeated use of CLIP-α- chymotrypsin in D-ester hydrolysis was demonstrated. Furthermore, this particular CLIP-α-chymotrypsin showed no loss in activity when it subsequently was used in the synthesis of N-acetyl-D-tryptophan ethyl ester in cyclohexane again. In the case of D-ester hydrolysis the reaction rate acceleration (k(enz)/k(nonenz)) was in the same order of magnitude of about 104 -105 mM-1 for the two CLIP-proteases. The results suggest that enzymes tailored by imprinting technique do not lose their induced 'new' property in the presence of water when they are prepared according to the described vinylation/crosslinking method (CLIP technique).
- Peissker, Fabian,Fischer, Lutz
-
-
Read Online
- Catecholamine-induced release of nitric oxide from N-nitrosotryptophan derivatives: A non-enzymatic method for catecholamine oxidation
-
In recent years, interest in the physiological functions of S-nitrosothiols has strongly increased owing to the potential of these compounds to release nitric oxide. In contrast, little is known about similar functions of N-nitrosated (N-terminal-blocked) tryptophan derivatives, which can be also formed at physiological pH. Utilizing N-acetyl-N-nitrosotryptophan (NANT) and N-nitrosomelatonin (NOMela) as model compounds, we have studied their reaction with catechol and catecholamines such as epinephrine and dopamine. In these reactions, NANT was quantitatively converted to N-acetyltryptophan (NAT), and nitric oxide was identified as a volatile product. During this process, ortho-semiquinone-type radical anions deriving from catechol and dopamine, were detected by ESR spectrometry. The catechol radical concentration was about eight times higher under normoxia than under hypoxia and a similar relationship was found for the decay rates of NANT under these conditions. An epinephrine-derived oxidation product, namely adrenochrome, but not a catechol-derived one, was identified. These observations strongly indicate that N-nitrosotryptophan derivatives transfer their nitroso-function to an oxygen atom of the catecholamines, and that the so-formed intermediary aryl nitrite may decompose homolytically with release of nitric oxide, in addition to a competing hydrolysis reaction to yield nitrite and the corresponding catechol. These conclusions were supported by quantum chemical calculations performed at the CBS-QB3 level of theory. Since nitric oxide is non-enzymatically released from N-nitrosotryptophan derivatives on reaction with catecholamines, there might be a possibility for the development of epinephrine-antagonizing drugs in illnesses like hypertension and pheochromocytoma. The Royal Society of Chemistry 2006.
- Kytzia, Anna,Korth, Hans-Gert,De Groot, Herbert,Kirsch, Michael
-
-
Read Online
- Structure-activity relationship studies of dipeptide-based hepsin inhibitors with Arg bioisosteres
-
Hepsin is a type II transmembrane serine protease (TTSP) associated with cell proliferation and overexpressed in several types of cancer including prostate cancer (PCa). Because of its significant role in cancer progression and metastasis, hepsin is an attractive protein as a potential therapeutic and diagnostic biomarker for PCa. Based on the reported Leu-Arg dipeptide-based hepsin inhibitors, we performed structural modification and determined in vitro hepsin- and matriptase-inhibitory activities. Comprehensive structure-activity relationship studies identified that the p-guanidinophenylalanine-based dipeptide analog 22a exhibited a strong hepsin-inhibitory activity (Ki = 50.5 nM) and 22-fold hepsin selectivity over matriptase. Compound 22a could be a prototype molecule for structural optimization of dipeptide-based hepsin inhibitors.
- Kwon, Hongmok,Ha, Hyunsoo,Jeon, Hayoung,Jang, Jaebong,Son, Sang-Hyun,Lee, Kiho,Park, Song-Kyu,Byun, Youngjoo
-
supporting information
(2020/12/25)
-
- Tryptophan derivative and application thereof
-
The invention discloses a tryptophan derivative or salt acceptable in feed, a stereoisomer, a tautomer, a solvate and a prodrug molecule of the tryptophan derivative. The tryptophan derivative has a structure shown in a formula (I). The tryptophan derivative as shown in the formula (I) and acceptable salt, stereoisomer, tautomer, solvate and prodrug molecules thereof in the feed all show more stable physicochemical properties than tryptophan in a raw material high thermal stability test and a normal temperature stability test of the feed. The content change of the tryptophan derivative does not exceed the acceptable change range of the feed additive or the feed in the test period; moreover, the compounds can effectively improve the growth of animals, feed conversion and other production performances, even have more excellent improvement effects than tryptophan, and can be used as animal feed additives or used for preparing animal feed additives or animal feeds.
- -
-
Paragraph 0192-0194
(2020/05/30)
-
- Reactivity of α-Amino Acids in the Reaction with Esters in Aqueous–1,4-Dioxane Media
-
The kinetics of the reaction of a series of α-amino acids with 4-nitrophenyl acetate, 4-nitrophenyl benzoate, and 2,4,6-trinitrophenyl benzoate in aqueous 1,4-dioxane medium has been studied. Kinetics of the reactions involving 4-nitrophenyl acetate and 2,4,6-trinitrophenyl benzoate has complied with the Br?nsted dependence and revealed linear correlation between rate constant logarithm and the energy difference of the frontier orbitals of α-amino acids anions.
- Kochetova,Kustova,Kuritsyn
-
-
- Synthesis and evaluation of oxindoles as promising inhibitors of the immunosuppressive enzyme indoleamine 2,3-dioxygenase 1
-
Indoleamine 2,3-dioxygenase 1 (IDO1) is considered as an important therapeutic target for the treatment of cancer, chronic infections and other diseases that are associated with immune suppression. Recent developments in understanding the catalytic mechanism of the IDO1 enzyme revealed that conversion of l-tryptophan (l-Trp) to N-formylkynurenine proceeded through an epoxide intermediate state. Accordingly, we synthesized a series of 3-substituted oxindoles from l-Trp, tryptamine and isatin. Compounds with C3-substituted oxindole moieties showed moderate inhibitory activity against the purified human IDO1 enzyme. Their optimization led to the identification of potent compounds, 6, 22, 23 and 25 (IC50 = 0.19 to 0.62 μM), which are competitive inhibitors of IDO1 with respect to l-Trp. These potent compounds also showed IDO1 inhibition potencies in the low-micromolar range (IC50 = 0.33-0.49 μM) in MDA-MB-231 cells. The cytotoxicity of these potent compounds was trivial in different model cancer (MDA-MB-231, A549 and HeLa) cells and macrophage (J774A.1) cells. Stronger selectivity for the IDO1 enzyme (124 to 210-fold) over the tryptophan 2,3-dioxygenase (TDO) enzyme was also observed for these compounds. These results suggest that the oxindole moiety of the compounds could mimic the epoxide intermediate state of l-Trp. Therefore, the structural simplicity and low-micromolar inhibition potencies of these 3-substituted oxindoles make them quite attractive for further investigation of IDO1 function and immunotherapeutic applications.
- Paul, Saurav,Roy, Ashalata,Deka, Suman Jyoti,Panda, Subhankar,Srivastava, Gopal Narayan,Trivedi, Vishal,Manna, Debasis
-
p. 1640 - 1654
(2017/08/22)
-
- Mild and eco-friendly chemoselective acylation of amines in aqueous medium using a green, superparamagnetic, recoverable nanocatalyst
-
Copper-grafted guanidine acetic acid-modified magnetite nanoparticles (Fe3O4@GAA-Cu(II)) as a green, superparamagnetic and recoverable nanocatalyst is found to promote quantitative N-acylation of various amines in a very short time with an equimolar amount of thioacetic acid in water at room temperature. This method is found to be highly selective for amines and not sensitive to other functional groups. Mild reaction condition, high selectivity, efficiency, simple workup and excellent yields are some of the major advantages of the procedure.
- Miraki, Maryam Kazemi,Yazdani, Elahe,Ghandi, Leila,Azizi, Kobra,Heydari, Akbar
-
-
- Feed additive method for preparing DL-tryptophan
-
The invention provides a method for preparing a feed additive DL-tryptophan. The method comprises the following steps of: 1) preparing indole-3-formaldehyde; 2) preparing aceturic acid; 3) preparing 3-indolyl-2-acetamino acrylic acid; 4) preparing N-acetyltryptophan; 5) preparing the DL-tryptophan. The method for preparing the feed additive DL-tryptophan is easy in acquisition of raw materials, low in raw material cost, high in reaction efficiency, and simple in process; the method can be carried out at the normal temperature and under the normal pressure without environmental pollution.
- -
-
Paragraph 0027; 0035; 0036
(2016/10/07)
-
- Peptide Tyrosinase Activators
-
Peptides that increase melanin synthesis are provided. These peptides include pentapeptides YSSWY, YRSRK, and their variants. The peptides may activate the enzymatic activity of tyrosinase to increase melanin synthesis. The pharmaceutical, cosmetic, and other compositions including the peptides are also provided. The methods of increasing melanin production in epidermis of a subject are provided where the methods include administering compositions comprising an amount of one or more peptides effective to increase the melanin production. The methods also include treating vitiligo or other hypopigmentation disorders with compositions including one or more peptides.
- -
-
-
- Synthesis of tripeptides containing d-Trp substituted at the indole ring, assessment of opioid receptor binding and in vivo central antinociception
-
The noncationizable tripeptide Ac-d-Trp-Phe-GlyNH2 was recently proposed as a novel minimal recognition motif for μ-opioid receptor. The introduction of different substituents (methyl, halogens, nitro, etc.) at the indole of d-Trp significantly influenced receptor affinities and resulted in serum stability and in a measurable effect on central antinociception in mice after ip administration.
- De Marco, Rossella,Bedini, Andrea,Spampinato, Santi,Gentilucci, Luca
-
supporting information
p. 6861 - 6866
(2014/10/15)
-
- Design, synthesis and evaluation of novel tacrine-(β-carboline) hybrids as multifunctional agents for the treatment of Alzheimer's disease
-
A series of tacrine-(β-carboline) hybrids (11a-q) were designed, synthesized and evaluated as multifunctional cholinesterase inhibitors against Alzheimer's disease (AD). In vitro studies showed that most of them exhibited significant potency to inhibit acetylcholinesterase (eeAChE and hAChE), butyrylcholinesterase (BuChE) and self-induced β-amyloid (Aβ) aggregation, Cu2+-induced Aβ (1-42) aggregation, and to chelate metal ions. Especially, 11l presented the greatest ability to inhibit cholinesterase (IC50, 21.6 nM for eeAChE, 63.2 nM for hAChE and 39.8 nM for BuChE), good inhibition of Aβ aggregation (65.8% at 20 μM) and good antioxidant activity (1.57 trolox equivalents). Kinetic and molecular modeling studies indicated that 11l was a mixed-type inhibitor, binding simultaneously to the catalytic anionic site (CAS) and the peripheral anionic site (PAS) of AChE. In addition, 11l could chelate metal ions, reduce PC12 cells death induced by oxidative stress and penetrate the blood-brain barrier (BBB). These results suggested that 11l might be an excellent multifunctional agent for AD treatment.
- Lan, Jin-Shuai,Xie, Sai-Sai,Li, Su-Yi,Pan, Long-Fei,Wang, Xiao-Bing,Kong, Ling-Yi
-
p. 6089 - 6104
(2015/02/02)
-
- Oxidative modification of native protein residues using cerium(IV) ammonium nitrate
-
A new protein modification strategy has been developed that is based on an oxidative coupling reaction that targets electron-rich amino acids. This strategy relies on cerium(IV) ammonium nitrate (CAN) as an oxidation reagent and results in the coupling of tyrosine and tryptophan residues to phenylene diamine and anisidine derivatives. The methodology was first identified and characterized on peptides and small molecules, and was subsequently adapted for protein modification by determining appropriate buffer conditions. Using the optimized procedure, native and introduced solvent-accessible residues on proteins were selectively modified with polyethylene glycol (PEG) and small peptides. This unprecedented bioconjugation strategy targets these under-utilized amino acids with excellent chemoselectivity and affords good-to-high yields using low concentrations of the oxidant and coupling partners, short reaction times, and mild conditions.
- Seim, Kristen L.,Obermeyer, Allie C.,Francis, Matthew B.
-
supporting information; experimental part
p. 16970 - 16976
(2011/12/04)
-
- Resolution of N-protected amino acid esters using whole cells of Candida parapsilosis ATCC 7330
-
Whole cells of Candida parapsilosis ATCC 7330 were used for the resolution of N-acetyl amino acid esters. Excellent enantioselectivities (E = 40 to >500) were achieved for the resolution of N-protected protein and non-protein amino acid esters giving good yields (28-50%) and high enantiomeric excesses (up to >99%) for both enantiomers.
- Stella, Selvaraj,Chadha, Anju
-
experimental part
p. 457 - 460
(2010/06/21)
-
- Synthesis and evaluation of β-carboline derivatives as inhibitors of human immunodeficiency virus
-
A series of β-carboline derivatives were synthesized by utilizing aromatization and chemoselective alkylation method recently reported from our laboratory. Synthesized derivatives were evaluated for anti-HIV activity in human CD4+ T cell line (CEM-GFP) infected with HIV-1 NL4.3 virus. 1-Formyl-β-carboline-3-carbxylic acid methyl ester (15) showed inhibition of human immunodeficiency virus at IC50 = 2.9 μM.
- Brahmbhatt, Keyur G.,Ahmed, Nafees,Sabde, Sudeep,Mitra, Debashis,Singh, Inder Pal,Bhutani, Kamlesh K.
-
body text
p. 4416 - 4419
(2010/09/18)
-
- D-aminoacylase mutants
-
The present invention provides mutant D-aminoacylases and use thereof. The mutant D-aminoacylases are hard to be inhibited by the substrate and, comprise the amino acid sequences of the D-aminoacylase derived from Alcaligenes denitrificans subsp. xylosoxydans MI-4 strain, wherein amino acid residues at specific sites have been modified. The mutants of the present invention have high reaction specificity as well as resistance to inhibition by the substrate. The present invention enables high-yield production of D-amino acids using higher concentrations of N-acyl-DL-amino acid as the substrate. The mutants of the present invention are useful in producing D-tryptophan in particular.
- -
-
-
- Chemical compounds
-
Compounds of the general structural formula (I) and use of the compounds and salts and solvates thereof, as therapeutic agents.
- -
-
-
- Fluorescence anisotropy and mobility of dansyl fluorophore in labelled homologous alkanes
-
Using the steady-state and time-resolved fluorescence anisotropy, the mobility of 5-(dimethylamino)naphthalene-1-sulfonyl (dansyl) fluorophore in homologous 1-[2-acetamido-3-(1H-indol-3-yl)propanamido[-n-]5-(dimethylamino)naphthalene-1-s ulfonamido]alkanes 1 was studied in binary solvents glycerol-water. Steady-state fluorescence data were evaluated by the generalized Perrin equation and the micro-Brownian motion of dansyl fluorophore was described by means of average characteristics (rotational relaxation times) of the rotational relaxation spectrum. The rotational relaxation time of "fast" motions caused by torsional vibrations of single bonds within the rotational-isomeric states decreases with increasing number of methylene groups in homologous compounds. The rotational relaxation time of "slow" motions due to conformational changes of the chain between the tryptophane and dansyl fluorophore remains at first approximately constant with increasing number of methylene groups but increases considerably for long aliphatic chains. The observed decrease in the rate of conformational changes of a long aliphatic chain is probably due to intramolecular interaction of parts of the methylene chain in a medium with high water content. The values of activation enthalpy ΔH+ and activation entropy ΔS≠ calculated from experimental data corroborate such interpretation. Time-resolved anisotropy of dansyl fluorophore at a particular binary solvent composition confirmed the shape of rotational relaxation spectrum and the measured rotational correlation times have been discussed. The time-dependent decays of anisotropy supported our previous interpretation in terms of intramolecular association of the long aliphatic chain in polar medium.
- Vyprachticky, Drahomir,Pokorna, Veronika,Pecka, Jan,Mikes, Frantisek
-
p. 1369 - 1384
(2007/10/03)
-
- Pronase catalysed peptide syntheses
-
A mixture of proteases from Streptomyces griseus (pronase), displaying a very broad substrate tolerance in the hydrolysis of peptides, has been studied for the first time systematically regarding their substrate specificity in peptide synthesis. It is demonstrated that pronase can be employed successfully for the formation of dipeptides with yields up to 95%. Pronase has also been employed successfully as catalyst for the enzyme assisted synthesis of a hexapeptide.
- Lobell, Mario,Schneider, Manfred P.
-
p. 319 - 325
(2007/10/03)
-
- Cross-linked crystals of subtilisin: Versatile catalyst for organic synthesis
-
Cross-linked enzyme crystals (CLECs) of subtilisin exhibit excellent activity in aqueous and various organic solvents. This catalyst is more stable than the native enzyme in both aqueous and mixed aqueous/organic solutions. Subtilisin-CLEC was shown to be a versatile catalyst. It was used for the syntheses of peptides and peptidomimetics, mild hydrolysis of amino acid and peptide amides, enantio- and regioselective reactions, and transesterifications.
- Wang, Yi-Fong,Yakovlevsky, Kirill,Zhang, Bailing,Margolin, Alexey L.
-
p. 3488 - 3495
(2007/10/03)
-
- Cosmetic composition
-
A composition suitable for topical application to mammalian skin and hair for inducing, maintaining or increasing hair growth comprises a hair growth promoter chosen from glutamine derivatives and salts thereof. The composition preferably also comprises an activity enhancer which may be chosen from hair growth stimulants, penetration enhancers and cationic polymers.
- -
-
-
- Cosmetic composition containing DOPA derivatives
-
A composition for topical application to human hair or skin contains a chemical analogue of dihydroxyphenyl alanine (DOPA). This chemical analogue can be absorbed by skin or by a hair follicle and metabolised in-vivo, thus leading to the formation of melanin in skin or to the growth of melanin-pigmented hair. Consequently the composition can give controlled skin darkening to mimic sun-induced tanning or can bring about the growth of dar hair in place of the grey or white hair.
- -
-
-
- Selectivity and Specificity in Substrate Binding to Proteases: Novel Hydrolytic Reactions Catalysed by α-Chymotrypsin Suspended in Organic Solvents with Low Water Content and Mediated by Ammonium Hydrogen Carbonate
-
α-Chymotrypsin suspended in organic solvents with low water content catalysed hydrolytic reactions in the presence of ammonium hydrogen carbonate.Molecular modelling studies were carried out and structure-reactivity relationships were established by studying the hydrolysis of amino acid derivatives and analogues.The enzyme was found to be stereoselective with respect to the hydrolysis of L-amino acid derivatives, but no stereoselectivity was observed when α-hydroxy esters were used as substrates.A general procedure for the resolution of aromatic amino acid esters is given.The results are interpreted in terms of molecular modelling based on X-ray crystallographic data and literature data.
- Ricca, Jean-Marc,Crout, David H. G.
-
p. 1225 - 1234
(2007/10/02)
-
- Cosmestic composition
-
A composition suitable for topical application to mammalian skin and hair for inducing, maintaining or increasing hair growth comprises a hair growth promoter chosen from glutamic acid derivatives and salts thereof. The composition preferably also comprises an activity enhancer which may be chosen from hair growth stimulants, penetration enhancers and cationic polymers.
- -
-
-
- Hair growth composition containing citric acid esters
-
Triesters of citric acid are used for inducing, maintaining or increasing hair growth. Compositions for topical application to mammalian hair or scalp comprise an effective amount of from 1% to 99% by weight of an ester of citric acid having the structure (1): where, R1, R2 and R3 each independently represent a branched or unbranched alkyl, alkenyl, aryl, alkylaryl or arylalkyl group, each said group having from 1 to 18 carbon atoms, R4 represents -H, or a branched or unbranched saturated or unsaturated acyl, alkyl, aryl, alkylaryl or aylalkyl group having from 1 to 18 carbon atoms, in the presence of a cosmetically acceptable vehicle for the citric acid ester and in the absence of solid absorbent for the ester;, said effective amount of said ester being sufficient to increase hair growth in the rat, when said composition is applied topically thereto over a period of no more than three months, by at least 10% more than that obtainable using a control composition from which the said ester has been omitted, in accordance with the Rat Hair Growth Test.
- -
-
-
- Catalysis by β-cyclodextrin in the reaction of p-nitrophenyl acetate with α-amino acids
-
The reactions of p-nitrophenyl acetate, 1, with both enantiomers of the following α-amino acids: alanine (2a), methionine (2b), leucine (2c), and tryptophan (2d), were studied in the presence of β-cyclodextrin (β-CD).All the reactions were catalyzed by β-
- Barra, Monica,Rossi, Rita H. de
-
p. 1124 - 1130
(2007/10/02)
-
- Cosmetic composition
-
A composition suitable for topical application to mammalian skin and hair for inducing, maintaining or increasing hair growth comprises a hair growth promoter chosen from N-acylated amino-acids, in which the acyl group has from 2 to 20 carbon atoms, together with a cosmetically acceptable vehicle for the hair growth promoter.
- -
-
-
- Efficient Asymmetric Hydrogenations of (Z)-2-Acetamidoacrylic Acid Derivatives with the Cationic Rhodium Complex of (2S,4S)-MOD-BPPM
-
The preparation of (2S,4S)-MOD-BPPM ((2S,4S)-N-(t-butoxycarbonyl)-4-phosphino>-2-phosphino>methyl>pyrrolidine) and its application to highly effective asymmetric hydrogenations of (Z)-2-acetamidoacrylic acid derivatives are described.
- Takahashi, Hisashi,Achiwa, Kazuo
-
p. 305 - 308
(2007/10/02)
-
- Acid-Sensitive Latent Inhibitors for Proteolytic Enzymes: Synthesis and Characterization
-
The reaction between peptide aldehydes and acylhydrazones affords derivatives that represent potential prodrugs for selective inhibition of lysosomal enzymes.BzPheal=Ala, obtained from the reaction between N-benzoyl-L-phenylalaninal and N-acetyl-L-alanine hydrazide, has been most carefully studied.When BzPheal=Ala is introduced into ongoing reactions catalyzed by α-chymotrypsin or papain, the rate of these reactions diminishes more rapidly with time than do those of controls lacking BzPheal=Ala.Furthermore, the disparity between run and control is much greater at pH 5 than at pH 7.The extent of inhibition (defined as explained in the text) at pH 5 can exceed that at pH 7 by 25-40-fold.The data are quantitatively explained by a reaction scheme that recognizes three important properties of BzPheal=Ala: (1) It undergoes hydrolysis at pH 5-7 to regenerate N-benzoyl-L-phenylalaninal; (2) the aldehyde thus liberated is a far more potent inhibitor for serine or cysteine proteases than is BzPheal=Ala; and (3) the rate constant for hydrolysis of BzPheal=Ala at pH 5 greatly exceeds that at pH 7.
- Silver, Marc S.,Haskell, John H.
-
p. 1253 - 1259
(2007/10/02)
-
- A general and accurate nmr determination of the enantiomeric purity of α-aminoacids and α-aminoacid derivatives
-
Derivatization of α-aminoacids, α-aminoesters and α-aminolactones as N-acetyl derivatives allow the accurate NMR determination of the enantiomeric purity. In these conditions the major coordination site with a chiral shift reagent will correspond to the NMR observation site. Experimental factors leading to the highest ΔΔδ values are ascertained. No straightforward correlation with absolute configurations can be established.
- Calmes, Monique,Daunis, Jacques,Jacquier, Robert,Verducci, Jean
-
p. 2285 - 2292
(2007/10/02)
-
- Enantioselective Catalysis, 4. Synthesis of N-Substituted (R,R)-3,4-Bis(diphenylphosphino)pyrrolidines. The Use of their Rhodium Complexes for the Asymmetric Hydrogenation of α-(Acylamino)acrylic Acid Derivatives
-
A simple synthesis of (R,R)-3,4-bis(diphenylphosphino)pyrrolidine (6a) and some N-substituted derivatives 6b-m is described. 6l and 6m are optically active tetraphosphanes, composed of two (R,R)-3,4-bis(diphenylphosphino)pyrrolidine units and a dicarboxylic residue.The structure of the parent compound 6a was determined by X-ray diffraction.From the phosphanes 6a-m the cationic 1,5-cyclooctadiene-bisphosphane-rhodium complexes 7a-m were prepared.The complexes 7l and 7m are ligand bridged bis(rhodium) dications.The complexes 7a-m were used for the asymmetric catalytic hydrogenation of the α-(acylamino)acrylic acid derivatives 9a-l.Enantiomeric excesses up to 100percent were achieved.Between 1 and 70 at the optical yields do not depend on the hydrogen pressure.The substrate/catalyst ratio can be as high as 50000/1.
- Nagel, Ulrich,Kinzel, Elke,Andrade, Juan,Prescher, Guenter
-
p. 3326 - 3343
(2007/10/02)
-
- OPTIMIZATION OF ENZYME CATALYZED PEPTIDE SYNTHESIS IN A "WATER - WATER-IMMISCIBLE ORGANIC SOLVENT" BIPHASIC SYSTEM
-
Optimal conditions were found for enzymatic synthesis of the dipeptide, N-acetyl-L-tryptophanyl-L-leucine amide in the biphasic system water - ethyl acetate.The synthesis was carried out using both free and immobilized α-chymotrypsin.Optimization was performed by such parameters as the "organic phase/aqueous phase" volume ratio, the pH of aqueous phase, and the concentration of starting reactants.Under most favourable conditions the dipeptide was synthesized on the preparative scale in ca. 100percent yield.As a result of immobilization (adsorption on the Sorsilen terephtalate support) the enzyme practically did not inactivate and may be used repeatedly.
- Khmel'nitski, Yu. L.,Dien, Fam Khyu,Semenov, A. N.,Martinek, Karel
-
p. 4425 - 4432
(2007/10/02)
-
- Cyclic acetals of N-acylglutamic acid-γ-semialdehydes, process for their production and use
-
The invention is directed to a cyclic acetal of N-acylglutamic acid-γ-semialdehyde of the formula STR1 in which A is an unsubstituted alkylene group having 2 to 3 carbon atoms or such an alkylene group substituted by 1 to 2 methyl groups and R is a methyl, methoxy, phenyl, or benzyloxy group and to a method of producing a compound of formula (I) by reaction of a compound of the general formula STR2 in which A is as defined above, with hydrogen cyanide or a cyanide ion supplying compound, ammonia or an ammonium ion supplying compound and carbon dioxide or a carbonate ion supplying compound and basic hydrolysis of the reaction mixture obtained and reaction of the hydrolysis mixture with a suitable acylating compound and use of the compounds of formula (I) to produce α-N-acyltryptophane.
- -
-
-
- Denitrosation of N-Acetyl-N1-nitrosotryptophan in Acid Solution
-
The denitrosation of DL-N-acetyl-N1-nitrosotryptophan has been studied kinetically in water in the acid range 4*10-2 - 1M-H2SO4 and also at lower acidities in buffer solutions pH 2-6.The reaction gave DL-N-acetyltryptophan and nitrous acid quantitatively and was not significantly reversible under these conditions.First-order behaviour was found for both the nitrosamine and acid in the sulphuric acid reactions, and the reaction was also acid-catalysed in the pH region 2-6.The reaction rate constant was unaffected by the addition of N-acetyltryptophan.In 0.04M -H2SO4 the rate constant was unchanged by the addition of bromide ion, thiocyanate ion, iodide ion, and thiourea, and the kinetic solvent isotope effect kH2O/kD2O was 1.3 at 0.7M-H2SO4 and 1.1 at 0.1M-H2SO4.However at pH 6 catalysis was observed by chloride, bromide, thiocyanate, azide, and iodide ion with increasing efficiency along this sequence.As the concentration of the nucleophile was increased the reaction rate constant tended to become independent of the nucleophile concentration.Thus N-acetyl-N1-nitrosotryptophan behaves as a typical nitrosamine at very low acidities around pH 6, whereas at higher acidities it shows a pattern of behaviour reminiscent of that shown by nitrosamides.The pH-rate profile for denitrosation shows clearly that there are two pathways associated with the acid-catalysed reaction, one predominant at around pH 4-7 and the other at acidities greater than pH 1.The former is associated with nucleophilic catalysis and the latter is not.The results are discussed in terms of two possible sites of protonation of the substrate (at O and C-3), and the changing effective rate limiting step, as the nucleophile concentration is changed.N-Acetyl-N1-nitrosotryptophan can be used to nitrosate (or diazotise) other species such as 4-nitroaniline, but only in the absence of a nitrous acid trap, indicating that this nitrosamine is not a direct nitrosating agent towards amines under these conditions.A minor photochemical decomposition pathway has been established for N-acetyl-N1-nitrosotryptophan at pH 6, but it was not examined in detail.
- Meyer, Thomas A.,Williams, D. Lyn H.,Bonnett, Raymond,Ooi, Suan L.
-
p. 1383 - 1388
(2007/10/02)
-
- SYNTHESIS OF L-TRYPTOPHAN FROM L-GLUTAMIC ACID
-
L-Tryptophan was synthesized from L-glutamic acid via L-glutamic-γ-semialdehyde derivatives with almost no racemization.KEYWORDS: L-tryptophan; L-glutamic acid; L-glutamic-γ-semialdehyde derivative; chiral derivative; chiral synthesis; Fischer indole synthesis
- Masumi, Fumio,Takeuchi, Hiroshi,Kondo, Shigeo,Suzuki, Kikuji,Yamada, Shun-ichi
-
p. 3831 - 3833
(2007/10/02)
-
- Tryptophan derivatives having an increased effect on the central nervous system
-
Tryptophan derivatives represented by the general formula: STR1 in which R denotes an acetyl group, M denotes an alkali metal or alkaline-earth metal (more particularly lithium or magnesium) having the value n or the quaternary ammonium cation of one of the following nitrogenous organic bases: morpholine and monoethanolamine; n is an integer equal to 1 or 2, and the formula (I) derivatives can be in the racemic DL form or the optically active L(+) form, the drugs being useful inter alia as agents having an increased effect on the central nervous system.
- -
-
-