Schoff P K, Cheetham J, Lardy H A
Institute for Enzyme Research, University of Wisconsin, Madison 53705.
J Biol Chem. 1989 Apr 15;264(11):6086-91.
Adenylate kinase (ATP:AMP phosphotransferase, EC 2.7.4.3) activity was detected in the flagella of ejaculated bovine spermatozoa. This activity provided sufficient ATP to produce normal motility in cells permeabilized with digitonin and treated with 0.5 mM MgADP. In the presence of ADP, adenylate kinase activity was inhibited by P1,P5-di(adenosine 5')-pentaphosphate (Ap5A), an adenylate kinase-specific inhibitor, and motility was stopped. ATP-supported motility was not affected by Ap5A. Mitochondrial adenylate kinase activity allowed AMP to stimulate respiration in permeabilized sperm. Adenylate kinase activity in tail fragments was most active in a pH range from 7.6 to 8.4, and a similar pH sensitivity was observed for this enzyme activity in a hypotonic extract of whole sperm. The apparent km of adenylate kinase activity in permeabilized tail fragments was about 1.0 mM ADP in the direction of ATP synthesis. The fluctuation of nucleotide concentrations in normal and metabolically stimulated sperm suggested that adenylate kinase was most active when the cell was highly motile, although adenylate kinase activity did not appear to be coupled strictly with motility.
在射出的牛精子鞭毛中检测到腺苷酸激酶（ATP：AMP磷酸转移酶，EC 2.7.4.3）活性。该活性提供了足够的ATP，以使经洋地黄皂苷通透处理并用0.5 mM MgADP处理的细胞产生正常运动。在存在ADP的情况下，腺苷酸激酶活性受到腺苷酸激酶特异性抑制剂P1，P5-二（腺苷5'）-五磷酸（Ap5A）的抑制，运动停止。ATP支持的运动不受Ap5A影响。线粒体腺苷酸激酶活性使AMP刺激通透化精子的呼吸。尾部片段中的腺苷酸激酶活性在pH 7.6至8.4范围内最活跃，并且在全精子的低渗提取物中观察到该酶活性具有相似的pH敏感性。在通透化的尾部片段中，腺苷酸激酶活性在ATP合成方向上的表观km约为1.0 mM ADP。正常和代谢刺激精子中核苷酸浓度的波动表明，当细胞高度运动时，腺苷酸激酶最活跃，尽管腺苷酸激酶活性似乎并未与运动严格耦合。
