title: Adenosine 3'5'-monophosphate phosphodiesterase of buffalo spermatozoa.
abstract: The cyclic AMP-phosphodiesterase (EC 3.1.4.17) of buffalo spermatozoa is distributed in the head, mid-piece and tail fractions and has multiple forms, 70% of which is in the bound form. The bound enzyme was not solubilized by Triton X-100, lubrol or hyamine 2389. Kinetic measurements of the soluble enzyme showed two apparent Km values for low and high cAMP concentrations, i.e. 4.5 and 100 micro M with Vmax values of 0.25 and 2.0 nmol cAMP hydrolysed min-1 mg protein-1. The bound enzyme had an apparent Km of 66.6 microM with a Vmax of 0.75 nmol cAMP hydrolysed min-1 mg protein-1. The pH for optimum enzyme activity was 7.5 and Mg2+ was essential for the activity of the soluble and bound enzymes. Methylxanthines, ATP, ADP and ppi inhibited the soluble and bound enzymes, ATP being the most potent inhibitor.
mesh_terms: D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000818:Animals; D002020:Buffaloes / Q000378:metabolism*; D008297:Male; D013094:Spermatozoa / Q000166:cytology / Q000201:enzymology*
chemical_list: D015105:3',5'-Cyclic-AMP Phosphodiesterases