[Enzymatic synthesis of acyl peptides containing p-nitroanilides of basic amino acids].

A method is suggested for synthesis of acylpeptides, containing arginine or lysine p-nitroanilides at the C-terminus, via the acyl transfer reaction catalyzed by the Bacillus subtilis serine proteinase. Acyl-di- and acyltripeptide ethers with L- and D-amino acids were used as the carboxyl component taken in a twofold excess. When the concentration of dimethylformamide increases, the hydrolysis of the initial ether and the reaction product diminishes.

[Determination of aspartame--methyl ester of L-aspartyl-L-phenyl- alanine using the amino acid analyzer].

A technique for quantitative determining of the synthetic sweetener aspartame. NH2-Asp-Phe-OMe and its hydrolysis product, NH2-Asp-Phe-OH, is proposed based on the use of an amino acid analyzer.

[Synthesis of p-nitroanilides of acylated peptides catalyzed by thermolysin].

Thermolysin-catalysed synthesis of p-nitroanilides of acylpeptides of general formula Z-A1-A2-pNA (A1 = Thr, Ala, Val, Leu; A2 = Leu, Phe) and stepwise synthesis of p-nitroanilides of acyltetrapeptides of general formula Z-A1-A2-A3-A4-pNA (A1, A2 = Gly,Ala; A3, A4 = Ala, Leu, Phe) from Z-A1-A2-OH and A3-pNA and then from Z-A1-A2-A3-OH and A4-pNA have been carried out; pNA group was eliminated enzymatically. Increase in solubility of the product in the reaction mixture diminishes its yield. Minimal amount of thermolysin providing a substantial yield of reaction product depends on structure of both amino and carboxylic components.

[Substrate specificity of Bacillus subtilis intracellular serine protease. Hydrolysis of insulin beta-chain, native ribonuclease A and p-nitroanilide peptide substrates].

Intracellular serine protease, termed ISP-103, was isolated from Bacillus subtilis, strain 103. The substrate specificity of the enzyme was compared to that of secretory subtilisins. Similar to subtilisins, ISP-103 cleaves a single peptide bond Ala20-Ser21 within the native pancreatic ribonuclease A, which results in the accumulation of trypsin-sensitive ribonuclease S, consisting of a non-covalently bound S-peptide (20 amino acid residues) and S-protein (104 amino acid residues).

[Affinity chromatography of subtilisin on a sorbent with epsilon-aminocapronyl-alanyl-alanyl-D-leucylamide. Detection of a serine protease with unusual properties].

A biospecific sorbent obtained by attachment of epsilon-aminocapronyl-L-alanyl-L-alanyl-D-leucylamide to CNBr-activated Sepharose 4B has been used for affinity chromatography of various samples of subtilisin BPN', e.g. subtilisin A ("Serva"), Nagarse, A-50.