Binding between Thermolysin and Its Specific Inhibitor, Phosphoramidon

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Abstract
Equilibrium and kinetic studies on the interaction between thermolysin (E) and its specific inhibitor (I), phosphoramidon ( N -(α-L-rhamnopyranosyloxyphospho)-L-leucyl-L-tryptophan), have been made by steady-state inhibitory kinetics analysis, fluorometric titration and the stopped-flow method. The inhibitor constant, K1 , the dissociation constant of the EI complex, Kd , directly obtained by fluorometric titration, and the apparent second-order association constant, Kon , obtained with the stopped-flow method are very similar to those for talopeptin (Kitagishi, K., et al . (1983) J. Biochem . 93, 47–53 and 55–59), whose molecular structure differs from that of phosphoramidon only in the configuration of the OH group at the C-4 atom of the sugar moiety. The result suggested that the OH group is not essential for the binding to thermolysin.