Braun T
J Cyclic Nucleotide Res. 1975;1(6):271-81.
The effect of divalent cations on bovine sperm adenylate cyclase activity was studied. Mn2+, Co2+, Cd2+, Zn2+, Mg2+ and Ca2+ were found to satisfy the divalent cation requirement for catalysis of the bovine sperm adenylate cyclase. These divalent cations in excess of the amount necessary for the formation of the metal-ATP substrate complex were found to stimulate the enzyme activity to various degrees. The magnitude of stimulation at saturating concentrations of the divalent cations was strikingly greater with M2+ than with either Ca2+, Mg2+, Zn2+, Cd2+ or Co2+. The apparent Km was lowest for Zm2+ (0.1 - 0.2 mM) than for any of the other divalent cations tested (1.2 - 2.3 mM). The enzyme stimulation by Mn2+ was decreased by the simultaneous addition of Co2+, Cd2+, Ni2+ and particularly Zn2+ and Cu2+. The antagonism between Mn2+ and Cu2+ or Zn2+ appeared to have both competitive and non-competitive features. The inhibitory effect of Cu2+ on Mn2+-stimulated adenylate cyclase activity was prevented by 2,3-dimercaptopropanol, but not by dithiothreitol, L-ergothioneine, EDTA, EGTA or D-penicillamine. Ca2+ at concentrations of 1-5 mM was found to act synergistically with Mg2+, Zn2+, Co2+ and Mn2+ in stimulating sperm adenylate cyclase activity. The Ca2+ augmentation of the stimulatory effect of Zn2+, Co2+, Mg2+ and Mn2+ appeared to be specific.
研究了二价阳离子对牛精子腺苷酸环化酶活性的影响。发现Mn2 +、Co2 +、Cd2 +、Zn2 +、Mg2 +和Ca2 +满足牛精子腺苷酸环化酶催化所需的二价阳离子条件。发现这些超过形成金属 - ATP底物复合物所需量的二价阳离子会不同程度地刺激酶活性。在二价阳离子饱和浓度下，M2 +的刺激程度明显大于Ca2 +、Mg2 +、Zn2 +、Cd2 +或Co2 +。对于Zn2 +（0.1 - 0.2 mM），其表观Km低于任何其他测试的二价阳离子（1.2 - 2.3 mM）。同时添加Co2 +、Cd2 +、Ni2 +，特别是Zn2 +和Cu2 +会降低Mn2 +对酶的刺激作用。Mn2 +与Cu2 +或Zn2 +之间的拮抗作用似乎具有竞争性和非竞争性特征。2,3 - 二巯基丙醇可阻止Cu2 +对Mn2 +刺激的腺苷酸环化酶活性的抑制作用，但二硫苏糖醇、L - 麦角硫因、EDTA、EGTA或D - 青霉胺则不能。发现浓度为1 - 5 mM的Ca2 +与Mg2 +、Zn2 +、Co2 +和Mn2 +协同作用，刺激精子腺苷酸环化酶活性。Ca2 +增强Zn2 +、Co2 +、Mg2 +和Mn +刺激作用的现象似乎具有特异性。
