DISTRIBUTION OF OXIDIZED AND REDUCED FORMS OF GLUTATHIONE AND CYSTEINE IN RAT PLASMA
DISTRIBUTION OF OXIDIZED AND REDUCED FORMS OF GLUTATHIONE AND CYSTEINE IN RAT PLASMA
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DOI：
10.1016/0003-9861(85)90065-7
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发表时间：
1985-01-01
影响因子：
3.9
通讯作者：
JONES, DP
中科院分区：
文献类型：
--
作者：
LASH, LH;JONES, DP
大鼠血浆中还原型谷胱甘肽基和氧化型谷胱甘肽基的分布与半胱氨酸基明显不同。谷胱甘肽基大部分以半胱氨酸和蛋白质混合二硫化物的形式存在；大部分半胱氨酸部分以胱氨酸的形式存在。70%的总谷胱甘肽等价物以二硫键与蛋白质结合。酸溶部分中谷胱甘肽当量的分布为谷胱甘肽28.0%，谷胱甘肽二硫化物9.5%，半胱氨酸混合二硫化物62.6%。相比之下，总半胱氨酸当量的23%是蛋白质结合的。半胱氨酸当量在酸溶部分的分布为5.9%为半胱氨酸，83.1%为胱氨酸，10.8%为混合二硫化物和谷胱甘肽基部分。谷胱甘肽的一级下降发生在血浆的体外培养中，这是由于谷胱甘肽与半胱氨酸和蛋白质混合二硫化物的形成增加。显然，血浆硫醇和二硫化物不是处于平衡状态，而是处于一种稳定状态，部分是通过这些化合物在代谢的器官间阶段在组织之间的运输来维持的。大量的蛋白结合谷胱甘肽和半胱氨酸提供了大量的缓冲，这在分析谷胱甘肽和半胱氨酸的瞬时变化时必须考虑到。这种缓冲可以防止瞬时硫醇-二硫化物氧化还原变化，从而影响血浆和质膜蛋白的结构和活性。
The distribution of the glutathionyl moiety between reduced and oxidized forms in rat plasma was markedly different than that for the cysteinyl moiety. Most of the glutathionyl moiety was present as mixed disulfides with cysteine and protein; most of the cysteinyl moiety was present as cystine. Seventy percent of total glutathione equivalents was bound to proteins in disulfide linkage. The distribution of glutathione equivalents in the acid-soluble fraction was 28.0% as glutathione, 9.5% as glutathione disulfide, and 62.6% as the mixed disulfide with the cysteinyl moiety. In contrast, 23% of the total cysteine equivalents was protein-bound. The distribution of cysteine equivalents in the acid-soluble fraction was 5.9% as cysteine, 83.1% as cystine, and 10.8% as the mixed disulfide with the glutathionyl moiety. A 1st-order decline in glutathione occurred upon in vitro incubation of plasma and was due to increased formation of mixed disulfides of glutathione with cysteine and protein. Apparently, plasma thiols and disulfides are not at equilibrium, but are in a steady-state maintained in part by transport of these compounds between tissues during the interorgan phase of their metabolism. The large amounts of protein-bound glutathione and cysteine provide substantial buffering which must be considered in analysis of transient changes in glutathione and cysteine. This buffering may protect against transient thiol-disulfide redox changes which could affect the structure and activity of plasma and plasma membrane proteins.