Phospholipase A2 and prostaglandins in human seminal plasma.

Lipolytic activity toward phospholipids in human seminal plasma had been ascribed to phospholipase A2 (17). The enzyme is soluble, heat stable at pH 5, requires Ca2+ for optimal activity, inhibited by ionic and nonionic detergents, and catalyzes the hydrolysis of the fatty acids in the 2 position of various sonicated phospholipids. In 12 healthy fertile and 20 subfertile individuals, the total phospholipase A2 activity toward radioactively labeled phosphatidylethanolamine has been compared with the total amounts of prostaglandins E and F, which have been determined by specific radioimmunoassay. There is a statistically significant correlation (p is less than 0.01) between total phospholipase A2 activity and prostaglandin E (and F) contents in the seminal plasma. It is concluded that phospholipase A2 is secreted along with prostaglandins into seminal plasma. This seminal phospholipase A2 possibly reflects the initial step of substrate release for prostaglandin biosynthesis in the human male reproductive system.