KINETIC CHARACTERIZATION OF ATRIAL NATRIURETIC FACTOR-SENSITIVE PARTICULATE GUANYLATE-CYCLASE
KINETIC CHARACTERIZATION OF ATRIAL NATRIURETIC FACTOR-SENSITIVE PARTICULATE GUANYLATE-CYCLASE
复制标题
DOI：
10.1016/0922-4106(90)90125-h
复制
发表时间：
1990-10-30
期刊：
影响因子：
--
通讯作者：
GERZER, R
中科院分区：
文献类型：
--
作者：
IVANOVA, K;HEIM, JM;GERZER, R
本研究描述了来自牛肾上腺皮质的膜结合和Triton x -100溶性心房钠素敏感鸟苷酸环化酶的动力学特性。两种酶形式的动力学分析表明，在锰存在的情况下，ANF诱导或稳定了至少两个表观GTP*Mn2+-和另外两个Mn2+-结合位点。利钠药物阿米洛利的加入有利于这种状态。在ANF存在下，ATP增加GTP*Mg2+的v(max)，但对GTP*Mn2+没有增加。对于GTP*Mg2+，阿米洛利对基础或anf刺激的活性没有影响，但略微降低ATP的作用。在所有测试条件下，该酶在Mg2+存在下遵循规则的Michaelis-Menten动力学，并与Mn2+表现出正的协同性。Triton萃取后还保留了正协同性。结果表明，在精心的提取过程中，Triton萃取对颗粒鸟苷酸环化酶的动力学性质没有太大的影响。这些数据还支持了ANF在Mn2+存在下激活酶时可能发生多种亚基相互作用的建议。
The present investigation describes kinetic characteristics of membrane-bound and Triton X-100-solubilized atrial natriuretic factor (ANF)-sensitive guanylate cyclase from bovine adrenal cortex. The kinetic analysis of both enzyme forms suggests that in the presence of manganese, ANF induces or stabilizes at least two apparent GTP*Mn2+- and in addition two Mn2+-binding sites. Addition of the natriuretic drug amiloride favors this state. ATP increases the v(max) in the presence of ANF for GTP*Mg2+, but not for GTP*Mn2+ as a substrate. With GTP*Mg2+, amiloride has no effect on basal or ANF-stimulated activity, but slightly reduces the effect of ATP. Under all conditions tested, the enzyme follows regular Michaelis-Menten kinetics in the presence of Mg2+ and exhibits positive cooperativity with Mn2+. Positive cooperativity is also retained after Triton extraction. The results indicate that Triton extraction has no major influence on the kinetic properties of particulate guanylate cyclase when the extraction procedure is done carefully. The data also support the suggestion that multiple interactions of subunits might occur upon activation of the enzyme by ANF in the presence of Mn2+.