Adang A E, Brussee J, Meyer D J, Coles B, Ketterer B, van der Gen A, Mulder G J
Department of Organic Chemistry, University of Leiden, The Netherlands.
Biochem J. 1988 Oct 15;255(2):721-4.
The substrate specificity of purified rat liver glutathione S-transferases (GSTs) for a series of gamma-glutamyl-modified GSH analogues was investigated. GST isoenzyme 3-3 catalysed the conjugation of 1-chloro-2,4-dinitrobenzene with six out of the nine analogues. alpha-L-Glu-L-Cys-Gly and alpha-D-Glu-L-Cys-Gly showed catalytic efficiencies of 40% and 130% that of GSH respectively. The GSH analogue with an alpha-D-glutamyl moiety appeared to be a highly isoenzyme-3-3-specific co-substrate: kcat./Km with GST isoenzyme 4-4 was only about 5% that with GST isoenzyme 3-3, and no enzymic activity was detectable with GST isoenzymes 1-1 and 2-2. GST isoenzyme 4-4 showed some resemblance to GST 3-3: five out of nine co-substrate analogues were accepted by this second isoenzyme of the Mu multigene family. Isoenzymes 1-1 and 2-2, of the Alpha multigene family, accepted only two alternative co-substrates, which indicates that their GSH-binding site is much more specific.
研究了纯化的大鼠肝脏谷胱甘肽S-转移酶（GSTs）对一系列γ-谷氨酰修饰的谷胱甘肽（GSH）类似物的底物特异性。GST同工酶3-3催化1-氯-2,4-二硝基苯与九种类似物中的六种发生结合反应。α-L-谷氨酰-L-半胱氨酰-甘氨酸和α-D-谷氨酰-L-半胱氨酰-甘氨酸的催化效率分别为GSH的40%和130%。带有α-D-谷氨酰部分的GSH类似物似乎是一种高度特异性作用于同工酶3-3的共底物：与GST同工酶4-4的kcat./Km仅约为与GST同工酶3-3的5%，并且用GST同工酶1-1和2-2未检测到酶活性。GST同工酶4-4与GST 3-3有一些相似之处：九种共底物类似物中的五种被Mu多基因家族的第二种同工酶所接受。Alpha多基因家族的同工酶1-1和2-2仅接受两种替代共底物，这表明它们的GSH结合位点特异性更强。
