GUANYLATE-CYCLASE OF ISOLATED BOVINE RETINAL ROD AXONEMES
GUANYLATE-CYCLASE OF ISOLATED BOVINE RETINAL ROD AXONEMES
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DOI：
10.1021/bi00590a006
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发表时间：
1979-01-01
期刊：
影响因子：
2.9
通讯作者：
DENISEVICH, M
中科院分区：
文献类型：
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作者：
FLEISCHMAN, D;DENISEVICH, M
研究了从牛视网膜杆中分离的轴丝-基底装置复合物的鸟苷酸环化酶活性。 GTP4- 的 Mg2+ 和 Mn2+ 络合物用作底物。每摩尔酶需要结合额外摩尔的 Mg2+ 或 Mn2+。无效阳离子为Ca2+、Ni2+、Fe2+、Fe3+、Zn2+ 和Co2+。该动力学与 Mg2+ 或 Mn2+ 与酶的结合必须先于 MgGTP 或 MnGTP 结合的机制一致。 Mg-酶复合物和Mn-酶复合物的表观解离常数为9.5倍。 10-4 和 1.1 倍。分别为10-4M。 MgGTP和MnGTP与相同金属酶复合物结合的表观解离常数是7.9倍。 10-4 和 1.4 倍。分别为10-4M。在pH 7-9 之间，环化酶活性最大并且与pH 无关。 KCl 和 NaCl 具有刺激作用，特别是在 Mg2+ 或 Mn2+ 浓度不理想的情况下。 Ca2+以及高浓度的Mg2+和Mn2+具有抑制作用。 Ca2+ 抑制可能需要每 mol 酶结合 2 mol Ca2+。 Ca2-酶复合物的解离常数约为1.4倍。 10-6M。轴丝基础装置制剂含有腺苷酸环化酶活性，其大小为鸟苷酸环化酶活性的1-10％。
The guanylate cyclase activity of axoneme-basal apparatus complexes isolated from bovine retinal rods was investigated. The Mg2+ and Mn2+ complexes of GTP4- served as substrates. Binding of an additional mol of Mg2+ or Mn2+ per mol of enzyme was required. Ineffective cations were Ca2+, Ni2+, Fe2+, Fe3+, Zn2+ and Co2+. The kinetics are consistent with a mechanism in which binding of Mg2+ or Mn2+ to the enzyme must precede binding of MgGTP or MnGTP. The apparent dissociation constants of the Mg-enzyme complex and Mn-enzyme complex were 9.5 .times. 10-4 and 1.1 .times. 10-4 M, respectively. The apparent dissociation constants for binding of MgGTP and MnGTP to the same metal enzyme complex were 7.9 .times. 10-4 and 1.4 .times. 10-4 M, respectively. The cyclase activity was maximal and independent of pH between pH 7-9. KCl and NaCl were stimulatory, especially at suboptimal concentrations of Mg2+ or Mn2+. Ca2+ and high concentrations of Mg2+ and Mn2+ were inhibitory. Ca2+ inhibition may require the binding of 2 mol of Ca2+/mol of enzyme. The dissociation constant of the Ca2-enzyme complex was approximately 1.4 .times. 10-6 M. The axoneme-basal apparatus preparations contain adenylate cyclase activity whose magnitude is 1-10% that of the guanylate cyclase activity.