[Effect of RGD-containing peptides on platelet aggregation].

The influence of new synthetic peptides ARGDS-NH2 and RGD-dFK (synthesized by the fermentative method) and VPNLRGDLQVLA (a fragment of the foot-and-mouth virus's surface peptide) on the ADP-induced human platelet aggregation in vitro was studied. All peptides were found to inhibit the human platelet aggregation, but the synthetic peptides (ARGDS-NH2 and RGD-dFK) showed the most pronounced effect. Significant decrease in the platelet aggregation was observed at their concentrations within 0.1-10 mM. ARGDS-NH2 and RGD-dFK inhibited the platelet aggregation stronger than the reference drug pentoxifylline at equivalent concentrations.

[Sequential attachment of arginine residues to peptides catalyzed by subtilisin. II. Effect of the nature of acylating and nucleophilic components and small amounts of water in organic solvents]. / Posledovatel'noe prisoedinenie ostatkov arginina k peptidam, kataliziruemoe subtilizinom. II. Vliianie prirody atsiliruiushchego i nukleofil'nogo komponentov i malykh kolichestv vody v organicheskom rastvoritele.

The reaction of Dnp(or Z)-Ala2-Xaa-OCH3 (Xaa = Ile of Val) with arginine amide or p-nitroanilide was studied in organic solvents, which was catalyzed by subtilisin sorbed on macroporous glass, It resulted in the formation of peptides containing one to four arginine residues: Dnp(or Z)-Ala2-Xaa-(Arg) 1-4-NH2. The number of arginine residues attached to the peptide depended on the water content in organic solvents, nature of the amino acid residue Xaa in the P1 position of the acylating component, and the type of the N-protective group. The reaction can be used for synthesizing arginine-containing substrates of convertases and cathepsins B, L, and O. A chromogenic substrate for duodenase Z-Ala2-Ile-Arg2-pNA was obtained.

[Sequential attachment of arginine residues to peptides, catalyzed by subtilisin. 1. Effect of organic solvent composition]. / Posledovatel'noe prisoedinenie ostatkov arginina k peptidam, kataliziruemoe subtilizinom. 1. Vliianie sostava organicheskogo rastvoritelia.

Subtilisin 72 sorbed on a macroporous glass catalyzed the condensation of Dnp(or Z)-Ala2-Leu-OCH3 with arginine amide in a mixture of DMSO and acetonitrile at a water content less than 0.07% (v/v). This reaction resulted in the sequential formation of peptides containing from one to four C-terminal arginine residues. The number of attached Arg residues depended on the DMSO concentration in the solvent mixture, which determined the local arginine excess on the sorbent surface, which significantly exceeded the molar arginine excess in the solution. This enzymic reaction opened up new opportunities for preparation of peptides with different content of arginine residues.

[Proteolytic enzymes from Streptomyces fradiae: a metalloendopeptidase, subtilisin-like, and trypsin-like proteinases]. / Proteoliticheskie fermenty Streptomyces fradiae: metalloéndopeptidaza, subtilizinopodobnaia i tripsinopodobnaia proteinazy.

Three proteolytic enzymes-the metalloproteinase, SFMP, and two serine proteinases, SFSP and SFTP-have been isolated and purified from the culture fluid of Streptomyces fradiae using chromatography on bacitracin-silochrome, bacitracin-Sepharose, DEAE-cellulose and fractionation by ammonium sulfate. Study of physico-chemical and functional properties of the enzymes and structural analysis revealed that SFMP is a cysteine-containing metalloendopeptidase with M(r) of 36 kDa, has a peak activity for synthetic substrates at pH 7.0-7.5 and at 60-65 degrees C and is stable at pH 7.0-9.0. The serine proteinase SFSP is related to subtilisin-like enzymes, has a M(r) of 29 kDa and a pH optimum at 7.5-8.5 at temperature up to 50 degrees C. The proteinase is stable at pH 4.0-9.0 and retains 30% of its activity at 70 degrees C. The other serine proteinase, SFTP, has a M(r) of 26 kDa and is related to trypsin-like enzymes. Its activity for synthetic substrates of trypsin is maximal at pH 6.8-8.8 at 50 degrees C. The enzyme is stable at pH 4.5-8.5 and at temperature below 50 degrees C. It has been shown that Streptomyces fradiae, like Streptomyces griseus and other Streptomycetes, possesses an ability to secrete serine proteinases (SFSP and SFTP) related to two evolutionally distinct families of serine proteinases, i.e., subtilisin and chymotrypsin families. SFMP and SFSP have been isolated and characterized for the first time.

[Enzymatic synthesis of peptides of arginine-chromophore substrates of metalloproteinases and carboxypeptidases]. / Fermentativnyi sintez peptidov arginina-khromofornykh substratov metalloproteinaz i karboksipeptidaz.

Subtilisin 72 sorbed on the surface of macroporous glass catalyzes a condensation of the esters of N-acylated peptides with arginine derivatives in organic solvents. The sorbed enzyme can be used repeatedly, which makes it possible to synthesize the chromophore substrates of metalloproteinases and carbopeptidases of the general formula Dnp-Ala-Ala-Xaa-Arg-NH2 (Xaa = Leu, Phe, Val, Ile). In tetrapeptides, metalloproteinases hydrolyze the Ala-Xaa bond with the removal of Dnp-Ala-Ala-OH, which can be determined spectrophotometrically. The chromophore substrates of carboxypeptidases of the B type (Dnp-Ala-Ala-Xaa-Arg-OH and Dnp-Ala-Ala-Arg-OH) are obtained by hydrolysis of the corresponding amides by trypsin.

[A transformylation reaction--transfer of an N-formyl residue to amino acids and peptides in nucleophilic groups--as a side reaction of peptide synthesis]. / Reaktsiia transformilirovaniia--perenos N-formil'nogo ostatka v proizvodnykh aminokislot i peptidov na nukleofil'nye gruppy--kak pobochnaia reaktsiia peptidnogo sinteza.

The formyl group transfer from N-formyl amino acids and their derivatives to other acceptors--amino acids esters and aniline, was studied. Formylamino acids with the free alpha-carboxyl group are more effective donors in transformylation than formyl peptides or esters of formylamino acids.