Selective alterations in responsiveness of guanylate cyclase to activation by nitroso compounds during enzyme purification.
Selective alterations in responsiveness of guanylate cyclase to activation by nitroso compounds during enzyme purification.
复制标题
在酶纯化过程中鸟苷酸环化酶对亚硝基化合物激活的反应性的选择性改变。
DOI：
10.1016/0304-4165(81)90471-2
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发表时间：
1981
期刊：
影响因子：
--
通讯作者：
Baricos,WH
中科院分区：
文献类型：
--
作者：
Ignarro,LJ;Barry,BK;Gruetter,DY;Ohlstein,EH;Gruetter,CA;Kadowitz,PJ;Baricos,WH
Partially purified, heme-free, hepatic soluble guanylate cyclase was activated by NO,S-nitrosocysteine and NO-heme complexes to the extent of 19–34-fold in the presence of 3 mM Mg2+, but only up to 2-fold in the presence of 3mM Mn2+, when the GTP concentration was 1 mM. Even with Mg2+, however, nitroprusside and nitrosoguanidine failed to activate guanylate cyclase. Dithiothreitol or cysteine and, to a much lesser extent, hematin or hemoglobin restored the capacity of nitroprusside and nitrosoguanidine to activate guanylate cyclase, and enhanced enzyme activation by NO. Restoration or enhancement of enzyme activation with thiols was unrelated to their reducing potential because nonthiol reductants such as dithionite and ascorbate failed to influence guanylate cyclase activation. Instead, thiols likely reacted with the nitroso compounds to formS-nitrosothiols, which were potent activators of guanylate cyclase. Similarly, heme-containing substances reacted with nitroso compounds to form NO-heme complexes, which are known to activate guanylate cyclase. Enzyme activation by nitroprusside and nitrosoguanidine was restored, and that by NO and NO-hemoglobin was enhanced, by addition of heated hepatic soluble fraction (devoid of guanylate cyclase activity). The heated soluble fraction appears to contain a partially heat-stable, thiol-containing component(s) of molecular weight greater than 5000, which may be in part responsible for the observed effects on enzyme activation. These data suggest that partial enzyme purification results in the removal of thiol components that are required for the full expression of guanylate cyclase activation.
