[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.

[A new method for determination of antithrombin III and its diagnostic significance]. / Novyi metod opredeleniia antitrombina III i ego diagnosticheskoe znachenie.

A new assay based on using an original chromogenic substrate (z-Ala-Ala-Arg-pNa) and designed for the determination of antithrombin III is described in the paper. It was used in examinations of patients with malignancy after surgery. The content of antithrombin III was detected to be lower in 12% of cases in 2 days after surgery. Additionally, patients with DIC, as complications after surgery, were examined to find out that the antithrombin III content was decreasing in them.

[Synthesis of modified peptides with C-terminal alpha-amino aldehydes]. / Sintez modifitsirovannykh peptidov, soderzhashchikh na C-kontse alpha-aminoal'degidy.

Various synthetic approaches to modified peptides with the C-terminal aldehyde group, capable of inhibiting a number of proteolytic enzymes belonging to the classes of thiol, serine, and aspartyl proteases, are considered. Both chemical methods, including solid phase peptide synthesis now widely used, and biocatalytic synthetic methods for obtaining these substances are discussed in detail.

[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.

[The interaction of carriers with proteolytic enzymes used for enzymatic synthesis of peptides in organic solvents]. / O vzaimodeistvii s nositeliami proteoliticheskikh fermentov, ispol'zuemykh dlia énzimaticheskogo sinteza peptidov v organicheskikh rastvoriteliakh.

The adsorption of some proteolytic enzymes on inorganic solvents (Silochromes C-80 and C-120, macroporous glass CPG-10, and celite 535) and the effect of sorption-desorption processes on the activity and stability of the enzymes have been studied. The ability of the enzymes to be adsorbed on the carrier depended on the specific surface of the carrier and properties of the enzyme. Adsorption-desorption processes did not affect the activity of the enzymes. Acetonitrile had no noticeable effect on the activity of the enzyme adsorbed on the inorganic carrier. The enzymes adsorbed on such carriers catalysed reactions in media with a low (4-5%) content of water, since the carrier seems to protect the enzyme from inactivation with organic solvents. The loading of carrier with enzyme influenced the rate of the enzymatic reaction, the optimal loading corresponding the value of the maximum adsorption of the enzyme on the carrier.

[Enzymatic synthesis of acyl peptides containing p-nitroanilides of basic amino acids]. / Fermentativnyi sintez atsilpeptidov, soderzhashchikh n-nitroanilidy osnovnykh aminokislot.

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. Because of the enzyme inactivation by dimethylformamide the latter's optimal concentration is 70-80%.

[Synthesis of p-nitroanilides of acylated peptides catalyzed by thermolysin]. / Sintez p-nitroanilidov atsilirovannykh peptidov, kataliziruemykh termolizinom.

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. In many cases the molar ratio of the enzyme and starting substances could be decreased to 1:10(6) as compared with the generally used ration 1:10(3)-1:10(4).