INHIBITION AND RECOGNITION STUDIES ON THE GLUTATHIONE-BINDING SITE OF EQUINE LIVER GLUTATHIONE-S-TRANSFERASE
INHIBITION AND RECOGNITION STUDIES ON THE GLUTATHIONE-BINDING SITE OF EQUINE LIVER GLUTATHIONE-S-TRANSFERASE
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DOI：
10.1042/bj2710161
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发表时间：
1990-10-01
影响因子：
4.1
通讯作者：
DSILVA, C
中科院分区：
文献类型：
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作者：
DSILVA, C
马肝谷胱甘肽S-转移酶已被证明是由两个相同的亚基的表观先生25 500和8.9的pl。在pH 6.5的动力学数据与1-氯-2，4-二硝基苯作为底物表明一个随机的快速平衡机制，这是支持使用谷胱甘肽类似物的抑制研究。S-（对溴苄基）谷胱甘肽和相应的N α-，已经发现，在pH 6.5时，CGlu-和CGly-取代的衍生物是谷胱甘肽转移酶的线性竞争性抑制剂，相对于GSH。N-乙酰化的S-（对溴苄基）谷胱甘肽减少结合100倍，而N-苯甲酰化和N-苄氧基羰基化废除结合的衍生物的酶。后者的效果已被归因于在该区域的酶的空间限制。酰胺化的甘氨酸羧基的S-（对溴苄基）谷胱甘肽减少bindign的13倍，而甲基化减少70倍的结合，表明在该地区的酶的空间限制和可能的静电相互作用。两个羧基的酰胺化使结合显著降低802倍，这与谷氨酸羧基与位于酶上的基团的静电相互作用一致。
Equine liver glutathione S-transferase has been shown to consist of two identical subunits of apparent Mr 25 500 and a pl of 8.9. Kinetic data at pH 6.5 with 1-chloro-2,4-dinitrobenzene as a substrate suggests a random rapid-equilibrium mechanism, which is supported by inhibition studies using glutathione analogues. S-(p-Bromobenzyl)glutathione and the corresponding N.alpha.-, CGlu- and CGly-substituted derivatives have been found, at pH 6.5, to be linear competitive inhibitors, with respect to GSH, of glutathione transferase. N-Acetylation of S-(p-bromobenzyl)glutathione decreases binding by 100-fold, whereas N-benzoylation and N-benzyloxycarbonylation abolish binding of the derivative to the enzyme. The latter effect has been attributed to a steric constraint in this region of the enzyme. Amidation of the glycine carboxy group of S-(p-bromobenzyl)glutathione decreases bindign by 13-fold, whereas methylation decreases binding by 70-fold, indicating a steric constraint and a possible electrostatic interaction in this region of the enzyme. Amidation of both carboxy groups decreases binding significantly by 802-fold, which agrees with electrostatic interaction of the glutamic acid carboxy group with a group located on the enzyme.