- Effect of freezing on the enzymatic coupling of specific amino acid-containing peptide fragments
-
The effect of freezing on the enzymatic coupling of highly specific amino acid-containing peptide fragments was investigated using trypsin, α-chymotrypsin, and Bacillus licheniformis Glu-specific endopeptidase as biocatalysts. Comparison with reactions at normal temperature indicates that freezing efficiently represses the cleavage of specific peptide bonds independent of their individual localisation and specificity achieving irreversible and efficient peptide bond formation without proteolytic side reactions. Copyright (C) 2000 Elsevier Science Ltd.
- Wehofsky, Nicole,Haensler, Marion,Kirbach, Sebastian W.,Wissmann, Johannes-Dieter,Bordusa, Frank
-
-
Read Online
- Preparation method of (S)-1 - (benzyloxycarbonyl) -5 -oxo-pyrrolidine -2 - formic acid
-
The invention discloses a preparation method of (S)-1 - (benzyloxycarbonyl) -5 -oxo-pyrrolidine -2 - formic acid, which mainly solves the complexity in the original process, and is long in period and high in cost. The method specifically comprises first steps of preparing L - benzyloxycarbonyl N - glutamic acid from - L - glutamic acid and a benzyloxycarbonyl donor, second steps of intramolecular condensation cyclization N - benzyloxycarbonyl - L - glutamic acid to obtain the N -benzyloxycarbonyl - L - glutamic acid crude product. The third The crude N - benzyloxycarbonyl - L - glutamic acid crude product and the organic amine base are mixed, and the organic amine salt form is prepared by the solubility of the product in a solvent, fourth (N -) - L - (benzyloxycarbonyl) S oxopyrrolidine -1 - formic acid is prepared by desalinating -5 - benzyloxycarbonyl -2 - glutamic acid. To the method, the high-purity product is prepared, and the yield and the quality are greatly improved.
- -
-
Paragraph 0014; 0018; 0022; 0026; 0030; 0034
(2021/09/01)
-
- PROCESSES FOR PREPARATION OF (S)-TERT-BUTYL 4,5-DIAMINO-5-OXOPENTANOATE
-
Provided are processes for the preparation of (S)-tert-butyl 4,5-diamino-5-oxopentanoate, or a salt, solvate, hydrate, enantiomer, mixture of enantiomers, or isotopologue thereof. Also provided are solid forms of various intermediates and products obtained from the processes.
- -
-
Paragraph 00316; 00321
(2019/03/12)
-
- A method for the preparation of amine to that (by machine translation)
-
The invention discloses a method for the preparation of amine to that, the specific step includes: to 2 - methyl - 3 - nitro benzoic acid as the raw material, to obtain 2 - bromomethyl - 3 - nitro-benzoic acid methyl ester; L - glutamic acid as the raw material to make the N - CBZ - L - glutamic acid; to N - CBZ - L - glutamic acid as the raw material to make the 3 - amino - 2, 6 - piperidine dione hydrochloride; to 2 - methyl - 3 - nitro-benzoic acid methyl ester with 3 - amino - 2, 6 - piperidine dione hydrochloride as the raw material to make the 3 - (4 - nitro - 1, 3 dihydro - 1 - oxo - 2 hydrogen - isoindol - 2 - yl) piperidine - 2, 6 - dione; to 3 - (4 - nitro - 1, 3 dihydro - 1 - oxo - 2 hydrogen - isoindol - 2 - yl) piperidine - 2, 6 - dione as raw materials to that amine. The method of the invention has simple technological process, raw material economic, few by-products, and purification is simple, high yield, environment-friendly and the like, after treatment is simple, has better practicability and application value, has great industrial prospects. (by machine translation)
- -
-
Paragraph 0035; 0041; 0042; 0055; 0056; 0069; 0070
(2018/07/30)
-
- Synthesis of fully protected (2R,3R,4S)-4-amino-7-guanidino-2,3-dihydroxy heptanoic acid
-
(2R,3R,4S)-4-Amino-7-guanidino-2,3-dihydroxyheptanoic acid (AGDHE), a common constituent of biologically active marine peptides, callipeltin A (1) and neamphamide A, was synthesized as its orthogonally protected derivative from L-glutamic acid in 15 steps. Guanidination by the Mitsunobu condition and osmium-catalyzed dihydroxylation of the corresponding Z-olefin were employed as the key steps.
- Yoshino, Ryo,Tokairin, Yoshinori,Konno, Hiroyuki
-
supporting information
p. 1604 - 1606
(2017/04/03)
-
- Synthesis and Kinetic Characterisation of Water-Soluble Fluorogenic Acyl Donors for Transglutaminase 2
-
Small glutamate-containing peptides bearing coumarin derivatives as fluorescent leaving groups attached to the γ-carboxylic acid group of the Glu residue were synthesised and investigated with regard to their potential to act as substrates for transglutam
- Wodtke, Robert,Schramm, Georg,Pietzsch, Jens,Pietsch, Markus,L?ser, Reik
-
p. 1263 - 1281
(2016/10/19)
-
- Synthesis and physicochemical characterization of the impurities of pemetrexed disodium, an anticancer drug
-
A physicochemical characterization of the process-related impurities associated with the synthesis of pemetrexed disodium was performed. The possibility of pemetrexed impurities forming has been mentioned in literature, but no study on their structure has been published yet. This paper describes the development of the synthesis methods for these compounds and discusses their structure elucidation on the basis of two-dimensional NMR experiments and MS data. The identification of these impurities should be useful for the quality control during the production of the pemetrexed disodium salt.
- Michalak, Olga,Gruza, Mariusz M.,Witkowska, Anna,Bujak, Iwona,Cmoch, Piotr
-
p. 10004 - 10031
(2015/08/06)
-
- Total synthesis of (-)-platensimycin by advancing oxocarbenium- and iminium-mediated catalytic methods
-
(-)-Platensimycin is a potent inhibitor of fatty acid synthase that holds promise in the treatment of metabolic disorders (e.g., diabetes and "fatty liver") and pathogenic infections (e.g., those caused by drug-resistant bacteria). Herein, we describe its total synthesis through a four-step preparation of the aromatic amine fragment and an improved stereocontrolled assembly of the ketolide fragment, (-)-platensic acid. Key synthetic advances include 1) a modified Lieben haloform reaction to directly convert an aryl methyl ketone into its methyl ester within 30 seconds, 2) an experimentally improved dialkylation protocol to form platensic acid, 3) a sterically controlled chemo- and diastereoselective organocatalytic conjugate reduction of a spiro-cyclized cyclohexadienone by using the trifluoroacetic acid salt of α-amino di-tert-butyl malonate, 4) a tetrabutylammonium fluoride promoted spiro-alkylative para dearomatization of a free phenol to assemble the cagelike ketolide core with the moderate leaving-group ability of an early tosylate intermediate, and 5) a bismuth(III)-catalyzed Friedel-Crafts cyclization of a free lactol, with LiClO4 as an additive to liberate a more active oxocarbenium perchlorate species and suppress the Lewis basicity of the sulfonyloxy group. The longest linear sequence is 21 steps with an overall yield of 3.8% from commercially available eugenol. Relay tactics: The stereocontrolled assembly of the potent antibiotic (-)-platensimycin in 21 steps and 3.8% yield from eugenol is described (see scheme; TBAF: tetrabutylammonium fluoride; Ts: toluene-4-sulfonyl). Highlights are 1) a rapid oxidative esterification of an acyl aromatic, 2) a reliable dialkylation protocol to form platensic acid, 3) a π-facial conjugate reduction of a dienone, 4) a TBAF-promoted alkylative dearomatization of a free phenol, and 5) a Friedel-Crafts closure of a free lactol.
- Eey, Stanley T.-C.,Lear, Martin J.
-
p. 11556 - 11573
(2015/01/16)
-
- Synthesis and anticonvulsant activity of (R)- and (S)-3-(Carbobenzyloxy- amino-1-glutarimidooxy)esters
-
A series of (R)- and (S)-3-carbobenzyloxy-amino-1-glutarimidooxy-esters (5a-e) ((R)-and (S)-methyl-1-(3-carbobenzyloxy-amino-I glutarimidooxy)acetate (5a), (R)-and (S)-ethyl-1-(3-carbobenzyloxy-amino-glutarimidooxy)acetate (5b), (R)- and (S)-ethyl-1-(3-carbo-benzyloxy-amino-glutarimidooxy)propionate (5c), (R)- and (S)-methyl-2-(3-carbobenzyloxy-amino-glutarimidooxy)butyrate (5d), (R)- and (S)-ethyl-2-(3-carbobenzyloxy-amino-glutarimidooxy)butyrate (5e) were synthesized and investigated their anticonvulsant activities.
- Lee, Do-Hun
-
p. 8125 - 8127
(2013/09/23)
-
- Synthesis and relaxometric characterization of a MRI Gd-based probe responsive to glutamic acid decarboxylase enzymatic activity
-
Novel contrast agent based systems, which selectively visualize specific cells, e.g., neurons in the brain, would be of substantial importance for the fast developing field of molecular magnetic resonance imaging (MRI). We report here the synthesis and in vitro validation of a Gd(III)-based contrast agent designed to act as an MRI responsive probe for imaging the activity of the enzyme glutamic acid decarboxylase (GAD) present in neurons. Upon the action of the enzyme, the Gd(III) complex increases its hydration sphere and takes on a residual positive charge that promotes its binding to endogenous macromolecules. Both effects contribute in a synergic way to generate a marked relaxation enhancement, which directly reports enzyme activity and will allow activity detection of GAD positive cells in vitro and in vivo selectively.
- Napolitano, Roberta,Pariani, Giorgio,Fedeli, Franco,Baranyai, Zsolt,Aswendt, Markus,Aime, Silvio,Gianolio, Eliana
-
p. 2466 - 2477
(2013/05/08)
-
- Papain-catalyzed peptide bond formation: Enzyme-specific activation with guanidinophenyl esters
-
The substrate mimetics approach is a versatile method for small-scale enzymatic peptide-bond synthesis in aqueous systems. The protease-recognized amino acid side chain is incorporated in an ester leaving group, the substrate mimetic. This shift of the specific moiety enables the acceptance of amino acids and peptide sequences that are normally not recognized by the enzyme. The guanidinophenyl group (OGp), a known substrate mimetic for the serine proteases trypsin and chymotrypsin, has now been applied for the first time in combination with papain, a cheap and commercially available cysteine protease. To provide insight in the binding mode of various Z-XAA-OGp esters, computational docking studies were performed. The results strongly point at enzyme-specific activation of the OGp esters in papain through a novel mode of action, rather than their functioning as mimetics. Furthermore, the scope of a model dipeptide synthesis was investigated with respect to both the amino acid donor and the nucleophile. Molecular dynamics simulations were carried out to prioritize 22 natural and unnatural amino acid donors for synthesis. Experimental results correlate well with the predicted ranking and show that nearly all amino acids are accepted by papain.
- de Beer, Roseri J.A.C.,Zarzycka, Barbara,Amatdjais-Groenen, Helene I.V.,Jans, Sander C.B.,Nuijens, Timo,Quaedflieg, Peter J.L.M.,van Delft, Floris L.,Nabuurs, Sander B.,Rutjes, Floris P.J.T.
-
experimental part
p. 2201 - 2207
(2012/05/05)
-
- S-2-Amino-4-cyanobutanoic acid (β-cyanomethyl-l-Ala) as an atom-efficient solubilising synthon for l-glutamine
-
Glutamine (Gln) is often a difficult amino acid to incorporate during solution-phase peptide synthesis, owing to poor solubility and unwanted dehydrations as side-reactions. Current approaches to solving these problems are highly atom-inefficient. Nα-Cbz-β-cyanomethyl-l-Ala is readily accessible by dehydration of Cbz-l-Gln. β-Cyanomethyl-l-Ala can be incorporated into short peptides easily by conventional methods. The nitrile is stable to the hydrogenolysis conditions used to remove Cbz and to acidic deprotection but is quantitatively hydrated to the γ-carboxamide of l-Gln with hydrogen peroxide. Thus β-cyanomethyl-l-Ala may represent a new, soluble, perfectly atom-efficient synthon for l-Gln.
- Beauchard, Anne,Twum, Elvis A.,Lloyd, Matthew D.,Threadgill, Michael D.
-
supporting information; experimental part
p. 5311 - 5314
(2011/10/30)
-
- Synthesis of N -[(3 S)-2,6-dioxo-1-(2-phenylethyl)-3-piperidinyl]-(2 S)-2-methylbutanamide (( - )-julocrotine)
-
The total synthesis of ( - )-julocrotine (1) starting from l-glutamic acid in 41% overall yield is described. The methodology utilizes protection, deprotection, and regioselection (carbonyl differentiation via oxazolidinone) protocols, and glutarimide ring formation is the key step.
- Silva, Luciano L.,Joussef, Antonio C.
-
experimental part
p. 1531 - 1534
(2011/08/21)
-
- Informative secondary chiroptics in binary molecular organogel systems for donor-acceptor energy transfer
-
Pyrene-doped l-glutamide-based lipidic derivatives with different alkyl lengths (Cn-g-Pyr; n = 4, 8 and 12) were newly synthesized. All of the Cn-g-Pyr dissolved and showed thermotopically and lyotropically-induced excimer formations accompanied by induction of the positive Cotton effect in their CD spectra, indicating chirally ordered stacking. However, when C4-g-Pyr and C12-g-Pyr were mixed in a certain molar ratio, an unusual CD pattern from positive to negative ones was observed. In this study, energy transfer efficiency was investigated in a binary system of Cn-g-Pyr with C12-g-TPP. The results revealed that simple modification of the alkyl length of Cn-g-Pyr enables enhancement of the energy transfer efficiency with C12-g-TPP.
- Miyamoto, Koji,Jintoku, Hirokuni,Sawada, Tsuyoshi,Takafuji, Makoto,Sagawa, Takashi,Ihara, Hirotaka
-
supporting information; experimental part
p. 4030 - 4035
(2011/08/21)
-
- An improved large scale procedure for the preparation of N-Cbz amino acids
-
A simple and scalable method for the preparation of N-Cbz protected amino acids is presented which uses a mixture of aqueous sodium carbonate and sodium bicarbonate to maintain the appropriate pH during the addition of benzyl chloroformate. The method has been extended to other N-protections and is amenable to large scale preparation of an intermediate toward Zofenopril, an ACE inhibitor.
- Pehere, Ashok D.,Abell, Andrew D.
-
experimental part
p. 1493 - 1494
(2011/05/16)
-
- Molecular-shape selectivity by molecular gel-forming compounds: Bioactive and shape-constrained isomers through the integration and orientation of weak interaction sites
-
A molecular gel system was assembled on carrier particles and the integrated effect of weak interaction sites enabled highly efficient separation of the bioactive and shape-constrained isomers of tocopherols, β-carotene, and polycyclic aromatic hydrocarbons (PAHs) by multiple interaction mechanisms.
- Mallik, Abul K.,Qiu, Hongdeng,Sawada, Tsuyoshi,Takafuji, Makoto,Ihara, Hirotaka
-
supporting information; experimental part
p. 10341 - 10343
(2011/10/31)
-
- Constrained peptidomimetics reveal detailed geometric requirements of covalent prolyl oligopeptidase inhibitors
-
Prolyl oligopeptidases cleave peptides on the carboxy side of internal proline residues and their inhibition has potential in the treatment of human brain disorders. Using our docking program FITTED, we have designed a series of constrained covalent inhibitors, built from a series of bicyclic scaffolds, to study the optimal shape required for these small molecules. These structures bear nitrile functional groups that we predicted to covalently bind to the catalytic serine of the enzyme. Synthesis and biological assays using human brain-derived astrocytic cells and endothelial cells and human fibroblasts revealed that these compounds act as selective inhibitors of prolyl oligopeptidase activity compared to prolyl-dipeptidyl-aminopeptidase activity, are able to penetrate the cells and inhibit intracellular activities in intact living cells. This integrated computational and experimental study shed light on the binding mode of inhibitors in the enzyme active site and will guide the design of future drug-like molecules.
- Lawandi, Janice,Toumieux, Sylvestre,Seyer, Valentine,Campbell, Philip,Thielges, Sabine,Juillerat-Jeanneret, Lucienne,Moitessier, Nicolas
-
experimental part
p. 6672 - 6684
(2010/04/28)
-
- Highly stereoselective synthesis of stereochemically defined polyhydroxylated propargylamines by alkynylation of N-benzylimines derived from (R)-glyceraldehyde
-
The addition of the lithium derivative of tert-butyldimethylsilyl propargyl ether to N-benzylimines derived from (R)-2,3-O-isopropylideneglyceraldehyde has been achieved with acceptable yields and high diastereoselectivities. The syn/anti diastereoselectivity of the addition reaction can be controlled and reversed by the appropriate use of Lewis acids as inline precomplexing agents. Double stereodifferentiation processes using imines derived from (R)-2,3-O-isopropylideneglyceraldehyde and (R)- or (S)-α-methylbenzylamine as starting materials occur with total stereocontrol to afford syn and anti vic-propargylamino alcohol derivatives with orthogonally protected hydroxymethyl groups on both sides of the central core. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
- Diez, Roberto,Badorrey, Ramon,Diaz-de-Villegas, Maria D.,Galvez, Jose A.
-
p. 2114 - 2120
(2008/02/06)
-
- Regioselective opening of N-Cbz glutamic and aspartic anhydrides with carbon nucleophiles
-
Depending on the experimental conditions, aspartic and glutamic anhydrides can be opened regioselectively with Grignard reagents, thus giving access to different isomers of chiral amino-ketoesters.
- Deguest, Geoffrey,Bischoff, Laurent,Fruit, Corinne,Marsais, Francis
-
p. 2120 - 2125
(2007/10/03)
-
- Easy saponification by metal silanolates: Application in SPPS and in (S)-5-hydroxynorvaline preparation
-
Alkali metal trimethylsilanolates, TMSO-, M+, has been used for efficient conversion of methyl esters into their corresponding anhydrous acid salts under mild non-aqueous conditions. This strategy has been applied to SPPS for the preparation of neurotoxin cyclic analogues and in (S)-5-hydroxynorvaline synthesis.
- Minta, Ewelina,Boutonnet, Cédric,Boutard, Nicolas,Martinez, Jean,Rolland, Valérie
-
p. 1795 - 1797
(2007/10/03)
-
- Nγ-Aryl glutamine analogues as probes of the ASCT2 neutral amino acid transporter binding site
-
Analogues of l-glutamine were designed and synthesized to test a hydrogen-bond hypothesis between ligand and neutral amino acid transporter ASCT2. The key design feature contains a substituted phenyl ring on the amide nitrogen that contains electron withdrawing and electron donating groups that alter the pKa of the amide NH. Through this study a preliminary binding site map has been developed, and a potent commercially available competitive inhibitor of the ASCT2 transporter has been identified.
- Esslinger, C. Sean,Cybulski, Kimberly A.,Rhoderick, Joseph F.
-
p. 1111 - 1118
(2007/10/03)
-
- Beta-strand mimetics and method relating thereto
-
Conformationally constrained compounds which mimic the secondary structure of β-strand regions of biologically active peptides and proteins are disclosed. Such β-strand mimetic structures have utility over a wide range of fields, including use as diagnostic and therapeutic agents. Libraries containing the β-strand mimetic structures of this invention are also disclosed as well as methods for screening the same to identify biologically active members.
- -
-
-
- BETA-STRAND MIMETICS AND METHOD RELATING THERETO
-
Conformationally constrained compounds which mimic the secondary structure of ?-strand regions of biologically active peptides and proteins are disclosed. Such ?-strand mimetic structures have utility over a wide range of fields, including use as diagnostic and therapeutic agents. Libraries containing the ?-strand mimetic structures of this invention are also disclosed as well as methods for screening the same to identify biologically active members.
- -
-
-
- PROCESS FOR THE SEPARATION OF RACEMIC MIXTURES
-
The present invention relates to a process for the separation of racemic mixtures comprising development of a denser molecular imprint on silica with a desired enantiomer by sol-gel-protocol comprising hydrolytic control polymerization of a silica source as the monomer and amino alkylsilane as a functional monomer in the presence of the desired enantiomer, capping of surface OH groups and desorption of ancapsulated enantiomer from the silica.
- -
-
-
- A simple, mild and efficient procedure for selective cleavage of prenyl esters using silica-supported sodium hydrogen sulphate as a heterogenous catalyst
-
Prenyl esters were selectively and efficiently cleaved under slightly acidic reaction conditions using silica-supported sodium hydrogen sulfate as a heterogenous catalyst at room temperature to regenerate the parent carboxylic acids in very high yields.
- Ramesh,Mahender,Ravindranath,Das, Biswanath
-
p. 1465 - 1467
(2007/10/03)
-
- Benzyl 4,6-dimethoxy-1,3,5-triazinyl carbonate as N-protecting reagent
-
A new active carbonate ester, benzyl 4,6-dimethoxy-1,3,5-triazinyl carbonate (Z-DMT), was prepared, and found to be a useful reagent for the introduction of benzyloxycarbonyl group into amines. Since Z-DMT is neither unstable nor irritating, it is practically useful.
- Hioki, Kazuhito,Fujiwara, Miho,Tani, Shohei,Kunishima, Munetaka
-
-
- New synthetic routes to α-amino acids and γ-oxygenated α-amino acids. Reductive denitration and oxidative transformations of γ-nitro-α-amino acids
-
Transformation of γ-nitro-α-amino acid derivatives into α-amino acids by reductive denitration, into the γ-oxo-α-amino acids by ozonolysis of the corresponding amino acid ester nitronate derivatives, and into γ-hydroxy-α-amino acid derivatives by subsequent reduction of the oxo functionality, can be achieved in good yields. As the γ-nitro-α-amino acid derivatives are prepared from N,O-protected dehydroalanines derivable from the corresponding alanine, serine and cysteine derivatives by specific routes, the overall procedures provide a means for selective conversion of these simple α-amino acids into more complex ones.
- Crossley, Maxwell J.,Fung, Yik M.,Kyriakopoulos, Efstathia,Potter, Jeffrey J.
-
p. 1123 - 1130
(2007/10/03)
-
- Geometrical optimisation of 1,1′-binaphthalene receptors for enantioselective molecular recognition of excitatory amino acid derivatives
-
A series of optically active 1,1′-binaphthalene-derived receptors with N-(pyridine-2,6-diyl)acetamide [CONH(py)] H-bonding sites in the 6,6′-positions has been prepared for the enantioselective complexation of the N-carbobenzyloxy (Cbz)-protected excitatory amino acids aspartic (Asp) and glutamic (Glu) acid via two COOH ... CONH(py) H-bonding arrays and additional secondary bonding interactions. The conformational homogeneity of the receptors is enhanced by locking the dihedral angle θ about the chirality axis through the C(1)-C(1′) bond of the 1,1′-binaphthalene moiety either by bridging the 2,2′-positions or by attaching bulky substituents to these centres. Computer modelling has shown that bridging is more efficient in locking this dihedral angle than the introduction of bulky substituents, and these predictions have been confirmed by 1H NMR binding studies in CDCl3 and in CDCl3-CD3OD 99.8:0.2. Plots of the enantioselectivity Δ(ΔG°) (difference in stability between diastereoisomeric complexes) in the recognition by the bridged receptors as a function of the enforced dihedral angle θ are peak-shaped, and the highest values have been measured in CDCl3 (300 K) for the complexation of the enantiomers of N-Cbz-Asp [Δ(ΔG°) = 6.9 kJ mol-1] and N-Cbz-Glu [Δ(ΔG°) = 5.2 kJ mol-1] by (R)-21 (θ = 86 ± 4°). The more stable diastereoisomeric complexes are highly structured, and tight host-guest bonding has been confirmed by the observation of up to five intermolecular NOEs. Enforcing the conformational homogeneity by bridging represents a new general principle for improving the chiral recognition potential of 1,1′-binaphthalene receptors.
- Lustenberger, Philipp,Martinborough, Esther,Mordasini Denti, Tiziana,Diederich, Francois
-
p. 747 - 761
(2007/10/03)
-
- The Synthesis of Chiral Dendrimeric Molecules Based on Amino Acid Repeat Units
-
The use of simple natural products for the synthesis of chiral dendrimeric molecules is discussed. The synthesis of dendrimeric poly-L-aspartic acid, poly-L-glutamic acid and poly-L-lysine is reported.
- Twyman, L. J.,Beezer, A. E.,Esfand, R.,Mathews, B. T.,Mitchell, J. C.
-
p. 3408 - 3460
(2007/10/03)
-
- The invention of radical reactions. Part 39. The reaction of white phosphorus with carbon-centered radicals. An improved procedure for the synthesis of phosphonic acids and further mechanistic insights
-
White phosphorus in tetrahydrofuran under argon reacts in a long radical chain reaction with carbon radicals derived from Barton PTOC esters. The reaction is initiated by traces of oxygen and strongly inhibited by TEMPO. From the duration of the induction period the chain length can be measured as approximately one million. Each P4 molecule can add up to two carbon radicals. Oxidation of the adducts provides a convenient synthesis of phosphonic acids in high yield. With H2O2 at 0°C oxidation to the appropriate phosphinic acids is fast. For sensitive natural products the further transformation to phosphonic acids is best carried out at room temperature with an excess of SO2. In this way even linoleic acid can be convened to the corresponding phosphonic acid in good yield without any attack on the skipped diene unit. TEMPO is also remarkable for its stabilization of white phosphorus in solution when exposed to oxygen. Likewise an ordinary phosphine, like tributyl phosphine, is also stabilized by small amounts of TEMPO.
- Barton, Derek H. R.,Vonder Embse, Richard A.
-
p. 12475 - 12496
(2007/10/03)
-
- Total synthesis of (+)-porothramycin B
-
The first total synthesis of (+)-porothramycin B (1b is described. Our synthetic pathway can be readily applied to the synthesis of other members of the pyrrolo[1,4]benzodiazepine antibiotics.
- Fukuyama, Tohru,Liu, Gang,Linton, Steven D.,Lin, Shao-Cheng,Nishino, Hiroshi
-
p. 2577 - 2580
(2007/10/02)
-
- Syntheses of Polypeptides by Hidrogenolysis of N-Benzyloxycarbonyl-Amino Acid Anhydrides
-
When anhydrides of N-benzyloxycarbonyl-DL-aspartic acid (Z-DL-Asp), Z-L-Asp, N-Z-DL-glutamic acid (Z-DL-Glu), Z-L-Glu and N-Z-3-aminoglutaric acid (Z-β-Agl) were hydrogenolyzed in N,N-dimethylformamide (DMF), polypeptides were obtained in high yields.Hydrogenolyses of Z-DL-Glu and Z-L-Glu in dioxane gave pyroglutamic acid.
- Munegumi, Toratane,Meng, Yan-Quing,Harada, Kaoru
-
p. 2748 - 2750
(2007/10/02)
-
- PEPTIDE SYNTHESIS CATALYZED BY NATIVE PROTEINASE K IN WATER-MISCIBLE ORGANIC SOLVENTS WITH LOW WATER CONTENT
-
Rection of Ac-Tyr-OEt with HBr.Gly-NH2, catalysed by free proteinase K in various water-miscible organic solvents in the presence of triethylamine and 5 mol percent of water, was studied.Some aliphatic alcohols and acetonitrile proved to be suitable solvents.The effect of water content (2 percent - 20 percent) on the synthesis of Ac-Tyr-Gly-NH2 was studied using acetonitrile as solvent.Lowering of the water content to 5 percent or 2 percent led to almost 100 percent yield of the desired dipeptide; higher water content accelerated the reaction reducing at the same time the yield of Ac-Tyr-Gly-NH2 due to the concurrent hydrolysis of the ester Ac-Tyr-OEt.No reaction was observed in the absence of base (triethylamine), wereas an excess of base only retarded the reaction.The enzyme is capable of catalyzing the peptide bond synthesis with N-acylamino acids or N-acyl peptides as acylating components, which may contain all types of L-amino acid residues (except Pro) in the P1 position.However, the peptide bond synthesis depends strongly on the amino component composition, particularly on the amino acid residue in the P'1 position.Only amides of glycine and of hydrophillic amino acids were acylated with Ac-Tyr-OEt; amides of hydrophobic amino acids enter the reaction only reluctantly or not at al.The presence of Leu or Phe in position P'2 and Leu in position P'3 has not so negative effect on acylation of the amino component as has in presence in the P'1 position.The choice of protecting groups for the α-carboxyl of the amino component is restricted only to amide and in some cases its undesired enzymatic removal was observed.Unprotected peptides seem to be suitable amino components.
- Cerovsky, Vaclav,Martinek, Karel
-
p. 2027 - 2041
(2007/10/02)
-
- Composition containing a penem or carbapenem antibiotic
-
Administration of an N-acylated amino acid in association with a penem or carbapenem antibiotic relieves or eliminates the renal problems associated with administration of the antibiotic alone. The amino acid derivative and antibiotic may be formulated together as a composition or administered separately, either simultaneously or sequentially. The composition may be prepared by simple mixing.
- -
-
-
- Purification and Characterization of Carboxyl Proteinase from Aspergillus kawachii
-
A carboxyl proteinase was purified from rice koji of Aspergillus kawachii to a homogeneous state on polyacrylamide gek electrophoresis.The molecular weight and isoelectric point of the enzyme wer 35,000 and 3.9, respectively.The enzyme was most active between pH 2.8 and 3.4 with hemoglobin as substrate, and stable in the pH range of 2.2-6.4.The optimum ttemperature of the enzyme reaction was at 50 grad.C.The serine content was highest and no methionine was found in the enzyme.The enzyme was inhibited by typical inhibitors for carboxyl proteinases such as DAN, EPNP, and SPI.
- Yagi, Fumio,Fan, Jianqiang,Tadera, Kenjiro,Kobayashi, Akira
-
p. 1029 - 1034
(2007/10/02)
-
- 2(1H)-Pyridone as Leaving Group in Acylation Reactions - Applications in Peptide Synthesis
-
Alkyl 2-pyridyl carbonates 3 or mixtures of 3 and the isomeric N-(alkoxycarbonyl)-2-pyridones 3' are useful for the introduction of urethane protective groups into amino acids.The N-protected amino acids 7 - 10 react with 2(1H)-pyridone (1a) using the carbodiimide method to yield 2-pyridyl active esters 11, which easily undergo coupling reactions with amino acid esters 12 with elimination of 1a to give peptides 13 in good yields as well as high optical purities.
- Effenberger, Franz,Brodt, Werner
-
p. 468 - 482
(2007/10/02)
-
- ACTION ON PEPTIDES BY WHEAT CARBOXYPEPTIDASE
-
A kinetic analysis has been performed with purified wheat carboxypeptidase by the use of N-acyl dipeptides, Z-Gly-Pro-Leu-Gly (Z=benzyloxycarbonyl), angiotensin II and bradykinin.The values of kcat were dramatically influenced by amino acid residues occupying the penultimate position from the carbonyl terminus of substrates.The structure of the substrate did not appreciably affect the Km values. Key Word Index - Triticum aestivum; Gramineae; wheat; carboxypeptidase; peptides; kinetic parameters.
- Umetsu, H.,Ichishima, E.
-
p. 591 - 592
(2007/10/02)
-