THE EFFECT OF SODIUM TETRATHIONATE ON CYANIDE CONVERSION TO THIOCYANATE BY ENZYMATIC AND NONENZYMATIC MECHANISMS
THE EFFECT OF SODIUM TETRATHIONATE ON CYANIDE CONVERSION TO THIOCYANATE BY ENZYMATIC AND NONENZYMATIC MECHANISMS
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DOI：
10.1002/jat.2550100511
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发表时间：
1990-10-01
影响因子：
3.3
通讯作者：
KIRBY, SD
中科院分区：
文献类型：
--
作者：
BASKIN, SI;KIRBY, SD
四硫酸钠已被提议作为氰化物解毒剂，尽管其毒性和抑制作用的报道罗丹斯。我们研究了四硫酸盐和类似物二硫酸盐对罗丹斯酶活性的影响，因为它们的结构与硫代硫酸盐相似，硫代硫酸盐是该酶的一种已知的磺胺硫供体。在460 nm处测定硫氰酸铁络合物的形成，测定豚鼠肝脏匀浆的Rhodanese活性。以硫代硫酸盐为底物时，罗丹斯的Km为6.7 mM， Vmax为0.67 .mu。Mol硫氰酸盐min-1 mg-1蛋白。在毫摩尔浓度（例如1 mM）范围内的四硫酸盐存在时，罗丹斯将氰化物转化为硫氰酸盐的作用受到抑制。二硫代铁对罗丹斯活性的影响可以忽略不计。硫代硫酸盐（1-100毫米）和二硫代硫酸盐都不能自发地（即非酶促）从氰化物中产生大量的硫氰酸盐。然而，在没有罗丹斯的情况下，四硫酸盐（1.0、10.0和100.0 mM）产生了硫氰酸盐的剂量依赖性增加。这些数据表明，四硫酸盐非酶解毒氰化物，这可能部分解释了它的解毒作用。
Sodium tetrathionate has been proposed as a cyanide antidote despite its reported toxicology and inhibitory effect on rhodanese. We investigated the effect of tetrathionate and an analog, dithionite, on rhodanese activity because of their structural similarity to thiosulfate, a known sulfane sulfur donor for this enzyme. Rhodanese activity of guinea pig liver homogenate was assayed by measuring the formation of ferric thiocyanate complex at 460 nm. With thiosulfate as a substrate, the Km for rhodanese was 6.7 mM and the Vmax was 0.67 .mu.mol thiocyanate min-1 mg-1 protein. The conversion of cyanide to thiocyanate by rhodanese was inhibited in the presence of tetrathionate at the millimolar concentration (e.g. 1 mM) range. Dithionite had a negligible effect on rhodanese activity. Neither thiosulfate (1-100 mM) nor dithionite produced significant amounts of thiocyanate from cyanide spontaneously (i.e. non-enzymatically). However, in the absence of rhodanese, tetrathionate (1.0, 10.0 and 100.0 mM) produced a dose-dependent increase in thiocyanate. These data suggest that tetrathionate detoxifies cyanide non-enzymatically, which may, in part, account for its antidotal effects.