Study of the structure of streptokinase conjugates with a hydrophilic vinylpyrrolidone copolymer.

The modification of streptokinase by a synthetic N-vinylpyrrolidone copolymer leads to formation of conjugates varying in structures according to the proportions of the components in the reaction medium. Based on data obtained from spectrophotometry, as well as sedimentation and diffusion analyses, it is shown that in the presence of excess protein in the reaction medium, formation of the main chain takes place via the copolymer associated with several protein globules. Under conditions of excess modifier copolymer, either single-site and/or multiple-site bonding is possible for the protein backbone, depending on the molecular weight of the copolymer.

[Structural-dynamic and functional properties of native and modified streptokinase].

The process of streptokinase modification by a polymer and the dynamics of protein molecules and the polymer in a protein-polymer (dialdehyde dextran, DAD) conjugate were studied with the aid of luminescent methods. Conclusions were drawn on the structure of the protein-DAD conjugate and the selection of optimum conditions for the preparation of modified streptokinase. It is shown that modified streptokinase is more stable to the action of denaturating agents.

[A study of native streptokinase and its polymeric derivative by means of small angle x-ray scattering].

The gyration radius (R0) of native streptokinase (SK) was found to be R0 = (40 +/- ) A by small-angle X-ray scattering. Experimental hydrodynamic characteristics of SK were S0(20),W = (2.8 +/- 0.

[The conformation properties and conformation stability of streptokinase and its polymer derivative].

The properties and conformational stability of the proteinaceous activator of fibrinolysis--native streptokinase--and its derivative obtained by modification with a linear hydrophilic copolymer based on N-vinylpyrrolidone, were studied by the circular dichroism method. It was shown that polymeric modification of streptokinase had no effect on the secondary structure, while the conformational stability of the modified protein to urea was higher than that of the native one. Studies on thermal stability of both native and modified forms of streptokinase showed that the inactivation rate was lower in the modified form as compared to the native one.