Preparation and physical properties of some C18 unsaturated fatty esters containingL-amino acid residues and methyl esters ofN-stearoylamino acids

Lipids ◽  
1990 ◽  
Vol 25 (5) ◽  
pp. 260-266 ◽  
Author(s):  
Marcel S. F. Lie Ken Jie ◽  
H. B. Lao ◽  
David W. Y. Leung
Keyword(s):  
Amino Acid ◽  
Physical Properties ◽  
Methyl Esters ◽  
Amino Acid Residues ◽  
Fatty Esters

Evidence for Biosynthetical Equivalence of the Epimeric Isoleucine Residues in Angolide

1972 ◽  
Vol 50 (4) ◽  
pp. 428-439 ◽  
Author(s):  
R. O. Okotore ◽  
D. W. Russell
Keyword(s):  
Amino Acid ◽  
Physical Properties ◽  
Acid Hydrolysis ◽  
Column Chromatography ◽  
Mass Spectra ◽  
Mathematical Treatment ◽  
Amino Acid Residues ◽  
Analytical Results ◽  
Cyclic Intermediate

Pithomyces sacchari was grown on media containing L-valine. Instead of the metabolite angolide (cyclo-L-α-hydroxyisovaleryl1-erythro-L-isoleucyl2-L-α-hydroxyisovaleryl3-threo-D-isoleucyl4), synthesized on un-supplemented media, it produced a mixture with very similar physical properties. Acid hydrolysis liberated erythro-L- and threo-D-isoleucines (1:1), and DL-valine in amounts proportional to the exogenous valine concentration; L-α-hydroxyisovaleric acid was the only other component. Radioactivity from L-valine-U-14C was incorporated without dilution into valine, and with extensive dilution into the hydroxy acid.Partial fractionation of the mixture was achieved by column chromatography. Mass spectra of two fractions, containing different proportions of valine, were compared with the spectrum of angolide. A simple mathematical treatment showed that the fractions contained angolide, its divaline homologue, and a homologue with only one isoleucine replaced by valine. This must be a 1: 1 mixture of the two possible isomers, since any deviation from this ratio is inconsistent with the analytical results. It follows that the erythro-L- and the threo-D-isoleucine residues of angolide are equivalent with respect to their replacement by valine. It is inferred that angolide biosynthesis involves a cyclic intermediate containing both amino acid residues in the L configuration.

Specific water-soluble substrates for chymotrypsin: Attempts for compensating diminished P1-S1 interactions

1988 ◽  
Vol 53 (11) ◽  
pp. 2884-2889 ◽  
Author(s):  
Volker Schellenberger ◽  
Ute Schellenberger ◽  
Hans-Dieter Jakubke
Keyword(s):  
Amino Acid ◽  
Methyl Esters ◽  
Water Soluble ◽  
Amino Acid Residues ◽  
Substrate Properties ◽  
Ester Moiety ◽  
Benzyl Esters ◽  
Peptide Esters ◽  
Acyl Donors ◽  
Positively Charged

N-Maleyl-L-amino acid and peptide esters were synthesized and employed as substrates for α-chymotrypsin. From the kcat/KM values can be suggested that benzyl esters are significantly better substrates than the appropriate methyl esters. Further improvement in the substrate properties results from the introduction of the p-nitrobenzyl ester moiety. The choline ester of benzyloxycarbonyl-L-phenylalanine with the highest kcat/KM value confirmed the P1' leaving group specificity for positively charged residues. From the kinetic data can be concluded that acyl donors with high kcat/KM values, which are useful in kinetically controlled enzymatic peptide synthesis, need not contain aromatic amino acid residues in the P1 position.

Detection and Location of N-Methyl-amino-acid Residues in N-Acyloligopeptide Methyl Esters by Mass Spectrometry

Nature ◽  
1968 ◽  
Vol 217 (5128) ◽  
pp. 547-548 ◽  
Author(s):  
B. C. DAS ◽  
S. D. GÉRO ◽  
E. LEDERER
Keyword(s):  
Mass Spectrometry ◽  
Amino Acid ◽  
Methyl Esters ◽  
Amino Acid Residues

scholarly journals Phosphonamidate analogues of dipeptides with carboxypeptidase A and β-lactamase-inhibitory activity: elucidation of the mechanism of β-lactamase inhibition by electrospray mass spectrometry

1996 ◽  
Vol 314 (2) ◽  
pp. 457-461 ◽  
Author(s):  
David J. PAYNE ◽  
John H. BATESON ◽  
David TOLSON ◽  
Brian GASSON ◽  
Teresa KHUSHI ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Amino Acid ◽  
Electrospray Mass Spectrometry ◽  
Methyl Esters ◽  
Amino Acid Residues ◽  
Carboxypeptidase A ◽  
Mechanism Of Inhibition ◽  
Primary Amino ◽  
Active Nature ◽  
Proline Derivatives

A series of phosphonamidate compounds with different P1´ amino acid residues have been shown to be irreversible inactivators of the serine β-lactamase from Enterobacter cloacae P99. The efficiency of inhibition (based on k2/K values) of P99 by these derivatives, ordered in decreasing potency, is: β-phenyl-β-Ala> L-Phe> β-Ala> Gly>D-Phe>D-Pro> D-thiazolidine. The D- and L-Phe compounds also inhibit carboxypeptidase A. The proline and thiazolidine derivatives were phosphonamidate methyl esters, whereas the others were salts of diacids. Electrospray mass spectrometry showed that equimolar mixtures of the P99 enzyme with each of the following derivatives, Gly, D-Phe, L-Phe, β-Ala and β-phenyl-β-Ala, effected efficient adduct formation (70–95% of enzyme modified), illustrating the particularly active nature of some of these compounds. All the primary amino acid derivatives gave a similar mass increment, which suggests the displacement of the variable P1´ part of the molecule. This observation provides evidence that the compounds phosphonylate the active-site serine, with the phosphonamidate bond as the scissile bond and the amino acid as the leaving group. The thiazolidine derivative (phosphonamidate methyl ester) also appeared to work by the same mechanism. The comparable proline derivatives caused lower than expected mass shifts of 227–229, and therefore it is proposed that with these compounds both the amino acid and the phosphonamidate ester methoxy group were displaced at the phosphorus atom during the inhibition process. Therefore, electrospray mass spectrometry has provided both a measure of potency and a rationale for the mechanism of inhibition of P99 by these compounds.

scholarly journals Calf chymosin as a catalyst of peptide synthesis

1992 ◽  
Vol 288 (3) ◽  
pp. 941-943 ◽  
Author(s):  
C A Abdel Malak
Keyword(s):  
Amino Acid ◽  
Peptide Synthesis ◽  
Methyl Esters ◽  
Amino Acid Residues ◽  
Hydrophobic Amino Acid ◽  
Peptide Bonds ◽  
Aspartate Proteinase ◽  
Specificity Pattern ◽  
Adjacent Amino Acid

Calf chymosin was shown to catalyse peptide synthesis optimally over the range pH 4-5, giving satisfactory yields of methyl esters or p-nitroanilides of benzyloxycarbonyl tetra- to hexa-peptides, provided that hydrophobic amino-acid residues form the new peptide bonds. The effectiveness of the enzyme depends also on the nature of adjacent amino-acid residues. As an aspartate-proteinase with a characteristic specificity pattern chymosin would be useful for the synthesis of middle-length peptides.

Microwave-Induced Ugi-Four Component Reactions: Synthesis of New Hetero- Steroid-Amino Acid Conjugates

2020 ◽  
Vol 17 (8) ◽  
pp. 641-647
Author(s):  
Preetismita Borah ◽  
Biswa Mohan Sahoo ◽  
Vhatkar Dattatraya Shivling ◽  
Bimal Krishna Banik
Keyword(s):  
Amino Acid ◽  
Conventional Method ◽  
Biological Activities ◽  
Methyl Esters ◽  
Side Reaction ◽  
Amino Acid Residues ◽  
Amino Acid Conjugates ◽  
Amino Acid Conjugate ◽  
Acid Conjugate ◽  
Amine Conjugates

Background: Aza-steroids are an important class of compounds because of their numerous biological activities. The hetero steroids have different hydrogen bonding ability and hydrophobicity in comparison to steroids. Materials and Methods: Microwave-induced synthesis of a novel type of hybrid hetero-steroid amine conjugates, following Ugi-four component reactions of steroidal amines with alanine and valine methyl esters as amino acid residues is described. Specifically, hetero-steroid-amino acid conjugate based on D-ring fused hetero steroidal amine, hetero-steroid-amino acid conjugate based on A-ring hetero steroidal amine, and hetero-steroidamino acid conjugate based on B-ring hetero steroidal amine are synthesized. Results and Discussion: The yield of the products under microwave-induced process was considerably higher than that obtained by the conventional method. In contrast to the conventional method for the synthesis of these molecules, microwave-induced method has several advantages. Conclusion: These include rapid reaction, a superior yield of the product, minimum side reaction, and economical microwave-induced process.

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