Boar acrosin. Association of an endogenous membrane proteinase with phospholipid membranes.

摘要: Acrosin, an enzyme required for fertilization, is endogenous proteinase associated with membranes of the sperm acrosome. Liposomes were utilized as a model system to evaluate mode association between highly purified boar acrosin and phospholipid bilayer membranes. Acrosin was observed bind liposomes containing acidic phospholipids such phosphatidylglycerol, cardiolipin, phosphatidylserine. There no apparent binding which consisted nonacidic phospholipids, thus indicating that ionic constituent binding. Increased strength caused significant reduction in acrosin-liposome inverse effect on enzyme-membrane dissociation. Acrosin-liposome dissociation similarly effected by increasing concentrations divalent cations at constant strength, reductions pH. Equilibrium experiments, anionic liposomes, suggest presence either multiple classes independent sites, or negative cooperativity, range affinity (Ka) from 2 x 10(11) M-1 low 3 10(8) high concentrations. The membrane-associated accessible concanavalin A, molecular weight substrates, demonstrating portion molecule exposed membrane surface. In addition, had hydrolysis soluble protein synthetic substrates. results demonstrate due part electrostatic charge interactions indicate has properties extrinsic protein.