[Chemical modification of the functional groups of streptokinase B in the water-soluble carbodiimide-nucleophile system].

Specific activity of streptokinase was decreased after incubation in the system containing I-ethyl-3(3-dimethyl aminopropyl) carbodiimide (EDC)--ethylene diamine. Under these conditions about 8 free amino groups and 38 free carboxylic groups were modified in the streptokinase molecule. The protein conformation and the state of tryptophane residues were altered. The streptokinase modified by means of EDC-ethylene diamine treatment lost its ability to form a stable complex with human plasminogen.