EFFECTS OF THIOL INHIBITORS ON HEPATIC GUANYLATE CYCLASE ACTIVITY - EVIDENCE FOR INVOLVEMENT OF VICINAL DITHIOLS IN EXPRESSION OF BASAL AND AGONIST-STIMULATED ACTIVITY
EFFECTS OF THIOL INHIBITORS ON HEPATIC GUANYLATE CYCLASE ACTIVITY - EVIDENCE FOR INVOLVEMENT OF VICINAL DITHIOLS IN EXPRESSION OF BASAL AND AGONIST-STIMULATED ACTIVITY
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DOI：
10.1016/0005-2744(78)90121-3
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发表时间：
1978-01-01
期刊：
影响因子：
--
通讯作者：
DERUBERTIS, FR
中科院分区：
文献类型：
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作者：
CRAVEN, PA;DERUBERTIS, FR
几种硫醇封闭剂抑制100，000 × 1000的基础大鼠鸟苷酸环化酶活性。用N-甲基-N“-硝基-N-亚硝基胍（MNNG）、NaN_3、NaNO_2和硝普钠（Nitroprusside）刺激酶活性。巯基阻断剂的相对抑制效能为CdCl_2>对羟基汞苯甲酸盐> N-乙基马来酰亚胺>亚砷酸盐>碘乙酰胺。基础和MNNG响应可溶性鸟苷酸环化酶活性的抑制亚砷酸盐显着增强等摩尔浓度的2，3-二巯基丙醇，但不是巯基乙醇。抑制可溶性鸟苷酸环化酶的亚砷酸盐或氯化镉被完全逆转过量的2，3-二巯基丙醇。定性相似的效果，观察DE-52纤维素纯化的可溶性肝鸟苷酸环化酶，并建议密切并列巯基参与酶活性的调节。由于几个原因，抑制巯基阻滞剂似乎是通过多种机制和/或网站的相互作用介导的：浓度的巯基抑制剂，没有影响基础活性显着抑制的反应的酶的次最大浓度MNNG。氯化镉废除的行动，过量的氯化锰刺激纯化鸟苷酸环化酶，但是一个相对无效的抑制剂时，氯化锰和GTP存在于等摩尔浓度。亚砷酸盐-2，3-二巯基丙醇在过量MnCl 2存在或不存在下均能有效抑制鸟苷酸环化酶活性。亚砷酸盐-2，3-二巯基丙醇增加了MnGTP的Km（对照，0.13 ± 0.01）。0.02 mM; 0.2 mM亚砷酸盐-2，3-二巯基丙醇，0.31 . ±. 0.03 mM），而CdCl 2对此参数无影响。肝颗粒鸟苷酸环化酶活性显着抑制亚砷酸2，3-二巯基丙醇，但不氯化镉。这些数据不仅表明，邻位二硫醇基团的基础鸟苷酸环化酶的活性和酶的激动剂的反应的表达所需的，但强烈建议参与一个以上的相互作用的含有游离巯基残基。
Several thiol blocking agents inhibit basal rat guanylate cyclase activity of 100,000 .times. g hepatic supernatant fractions and the stimulation of enzyme activity by N-methyl-N'' -nitro-N-nitrosoguanidine (MNNG), NaN3, NaNO2 and nitroprusside. The relative potency of the thiol blockers as inhibitors was CdCl2 > p-hydroxymercuribenzoate > N-ethylmaleimide > arsenite > iodoacetamide. Inhibition of basal and MNNG-responsive soluble guanylate cyclase activities by arsenite was markedly potentiated by an equimolar concentration of 2,3-dimercaprol, but not by mercaptoethanol. Inhibition of soluble guanylate cyclase by either arsenite or CdCl2 was completely reversed by excess 2,3-dimercaprol. Qualitatively similar effects were observed with DE-52 cellulose purified soluble hepatic guanylate cyclase, and suggested an involvement of closely juxtaposed thiol groups in the regulation of enzyme activity. For several reasons inhibition by thiol blockers appeared to be mediated through multiple mechanisms and/or sites of interaction: concentrations of the thiol inhibitors which had no effect on basal activity strikingly inhibited the responsiveness of the enzyme to a submaximal concentration MNNG. CdCl2 abolished the action of excess MnCl2 to stimulate purified guanylate cyclase, but was a relatively ineffective inhibitor when MnCl2 and GTP were present in equimolar concentrations. Arsenite-2,3-dimercaprol was uniformly effective in inhibiting guanylate cyclase activity in the presence or absence of excess MnCl2. Arsenite-2,3-dimercaprol increased the Km for MnGTP (control, 0.13 .+-. 0.02 mM; 0.2 mM arsenite-2,3-dimercaprol, 0.31 .+-. 0.03 mM), whereas CdCl2 had no effect on this parameter. Hepatic particulate guanylate cyclase activity was significantly inhibited by arsenite 2,3-dimercaprol but not by CdCl2. The data not only indicate that vicinal dithiol groups are required for expression of basal guanylate cyclase activity and enzyme responses to agonists, but strongly suggest the involvement of more than one interacting the containing free thiol residues.