Kinetics of inhibition of sperm ß-acrosin activity by suramin

Abstract

Sperm ß-acrosin activity is inhibited by suramin, a polysulfonated naphthylurea compound with therapeutic potential as a combined antifertility agent and microbicide. A kinetic analysis of enzyme inhibition suggests that three and four molecules of suramin bind to one molecule of ram and boar ß-acrosins respectively. Surface charge distribution models of boar ß-acrosin based on its crystal structure indicate several positively charged exosites that represent potential 'docking' regions for suramin. It is hypothesised that the spatial arrangement and distance between these exosites determines the capacity of ß-acrosin to bind suramin.