ENZYMIC SYNTHESIS OF DIMETHYL SELENIDE FROM SODIUM SELENITE IN MOUSE LIVER EXTRACTS
ENZYMIC SYNTHESIS OF DIMETHYL SELENIDE FROM SODIUM SELENITE IN MOUSE LIVER EXTRACTS
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DOI：
10.1021/bi00867a039
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发表时间：
1966-01-01
期刊：
影响因子：
2.9
通讯作者：
GANTHER, HE
中科院分区：
文献类型：
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作者：
GANTHER, HE
以小鼠肝脏提取物为模型体系，研究了亚硒酸钠酶法合成硒化二甲基。在碳-14和硒-75双标记研究中，二甲基硒化物被确定为主要挥发性产物。肝脏165,000 x g上清部分和洗涤微粒体都合成硒化二甲基，但两者的活性都不如9000 x g上清部分。活性与蛋白质浓度成正比，加热后的提取物无活性。确定了整体反应的最佳条件。粗制体系对谷胱甘肽有特定的要求，不能被各种硫醇或二硫苏糖醇所消除。s -腺苷- l-蛋氨酸可能是甲基供体。还需要还原三磷酸吡啶核苷酸，辅酶A，腺苷5 -三磷酸和Mg才能达到最佳活性。与在空气中孵育相比，在N条件下孵育使硒化二甲基的产率提高了约10倍，这显然是由于防止了硫的不稳定还原形式的氧化。在大量过量硫醇存在的情况下，10-6 M亚砷酸盐抑制了50%的粗体系，Cd也抑制了粗体系。讨论了硒的谷胱甘肽衍生物在有机硒化合物合成中的可能作用。
The enzymic synthesis of dimethyl selenide from sodium selenite was studied with mouse liver extracts as a model system for the reductive utilization of selenium. Dimethyl selenide was identified as the major volatile product in doubly labeled studies with carbon-14 and selenium-75. Both the 165,000 x g supernatant fraction of liver and washed microsomes synthesize dimethyl selenide, but neither fraction is as active as a 9000 x g supernatant fraction. Activity is proportional to protein concentration, and heated extracts are inactive. Optimal conditions were determined for the over-all reaction. The crude system has a specific requirement for glutathione that cannot be eliminated by various thiols or by dithiothreitol. S-Adenosyl-L-methionine is the probable methyl donor. Reduced triphosphopyridine nucleotide, co-enzyme A, adenosine 5[image]-triphosphate, and Mg are also required for optimal activity. Incubation under N increases the yield of dimethyl selenide approximately 10-fold compared to incubation in air, apparently by preventing the oxidation of labile reduced forms of S. The crude system is inhibited 50% by 10-6 M arsenite in the presence of a large excess of thiols and is also inhibited by Cd. The possible role of glutathione derivatives of Se in the synthesis of organoselenium compounds is discussed.