[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.