水牛精子的3',5'-环磷酸腺苷磷酸二酯酶

Adenosine 3'5'-monophosphate phosphodiesterase of buffalo spermatozoa.

作者信息

Bhatnagar S K, Chaudhry P S, Anand S R

出版信息

J Reprod Fertil. 1979 May;56(1):133-9. doi: 10.1530/jrf.0.0560133.

DOI:10.1530/jrf.0.0560133

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.

摘要

水牛精子的环磷酸腺苷磷酸二酯酶（EC 3.1.4.17）分布于头部、中段和尾部组分中，且具有多种形式，其中70%为结合形式。结合型酶不能被曲拉通X-100、十二烷基聚氧乙烯醚或十六烷基三甲基氢氧化铵溶解。对可溶性酶的动力学测量显示，对于低和高浓度的环磷酸腺苷有两个表观Km值，即4.5和100 μM，Vmax值分别为0.25和2.0 nmol环磷酸腺苷水解·min⁻¹·mg蛋白⁻¹。结合型酶的表观Km为66.6 μM，Vmax为0.75 nmol环磷酸腺苷水解·min⁻¹·mg蛋白⁻¹。酶活性的最适pH为7.5，Mg²⁺对可溶性和结合型酶的活性均至关重要。甲基黄嘌呤、ATP、ADP和焦磷酸抑制可溶性和结合型酶，ATP是最有效的抑制剂。