title: Investigations on adenosine 3',5'-monophosphate phosphodiesterase in ram semen and initial characterization of a sperm-specific isoenzyme.
abstract: Phosphodiesterase is shown to occur in ram semen, and its activity to be higher in spermatozoa than in seminal plasma. Using similar substrate levels, the rate at which adenosine 3',5'-monophosphate (cyclic AMP) is metabolized by phosphodiesterase in spermatozoa is about 100 times higher than that of cyclic AMP synthesis by adenylate cyclase. In spermatozoa, phosphodiesterase is present partly in a soluble form, and partly bound; both forms can be extracted by sonication. The soluble enzyme (pH optimum 8-0, Km = 1-5 muM, mol. wt 165,000) occurs as a single isoenzyme, as shown by polyacrylamide gel electrophoresis and anion-exchange chromatography; this isoenzyme appears to be specific for spermatozoa and its formation in the testis coincides with the appearance of spermatozoa. The bound sperm enzyme has been solubilized with Trion X-100; it is a single isoenzyme (pH optimum 8-0, mol. wt 165,000) which is electrophoretically different from the soluble form, but similar to the phosphodiesterase found in other tissues. Seminal plasma phosphodiesterase (pH optimum 8-8, mol. wt 165,000) is present in the form of three isoenzymes; all three are different from the two forms of sperm phosphodiesterase, but are similar to the isoenzymes found in certain male accessory organs.
mesh_terms: D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000302:isolation & purification / Q000378:metabolism*; D000818:Animals; D004591:Electrophoresis, Polyacrylamide Gel; D007527:Isoenzymes / Q000378:metabolism; D008297:Male; D008970:Molecular Weight; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism*; D012661:Semen / Q000201:enzymology*; D012756:Sheep / Q000378:metabolism*; D013094:Spermatozoa / Q000201:enzymology*
chemical_list: D007527:Isoenzymes; D010727:Phosphoric Diester Hydrolases; D015105:3',5'-Cyclic-AMP Phosphodiesterases