FLUORESCENCE-LABELED STREPTOMYCES SUBTILISIN INHIBITOR - ANALYSIS OF THE INTERACTION WITH SUBTILISIN AND STREPTOMYCES-GRISEUS PROTEASES

Specific labeling of the Lys-89 residue of Streptomyces subtilisin inhibitor (SSI) was carried out by fluorescein isothiocyanate. The dimeric structure of SSI, which is composed of identical subunits, was not changed upon modification and the resulting fluorescent SSI was fully active as an inhibitor. Induced conformational change in the vicinity of the modified residue of SSI followed by complexation with subtilisin was evidenced by fluorescence spectra. Dissociation of the subunits was also shown to be associated with the change in the fluorescence spectra. © 1990.