Phospholipid vesicle stimulation of proacrosin activation.

Aqueous dispersions of synthetic phospholipids, in the form of anionic, single bilayer vesicles, were observed to stimulate the appearance of acrosin esterase activity from its zymogen precursor, proacrosin. Enzymatic activity measurements, in parallel with polyacrylamide disc gel electrophoresis in the presence of sodium dodecyl sulfate, indicated that the enzymatic activity produced had resulted from the conversion of proacrosin to acrosin (EC 3.4.21.10), and not from the direct stimulation of a possible proacrosin esterase activity. It is suggested that such bilayer lipid vesicles can be used as a model membrane system to study the activation of proacrosin in vitro.