Premium
Inhibition of various isoforms of rat liver glutathione S‐transferases by tannic acid and butein
Author(s) -
Zhang Kai,
Mack Peter,
Wong Kim Ping
Publication year - 1997
Publication title -
iubmb life
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.132
H-Index - 113
eISSN - 1521-6551
pISSN - 1521-6543
DOI - 10.1080/15216549700203121
Subject(s) - tannic acid , chemistry , gene isoform , glutathione , isozyme , chloride , biochemistry , ic50 , in vitro , enzyme , organic chemistry , gene
Abstract Glutathione S‐transferases (EC.2.5.1.18, GSTs) were purified from rat liver by S‐hexylglutathione affinity chromatography and six isoforms, namely C‐1, C‐2, C‐3, C‐4, A‐2 and A‐1, were isolated by CM‐cellulose and DEAE‐cellulose ion‐exchange columns. Tannic acid and butein showed varying degrees of inhibition on the six individual GST isoforms. When 1‐chloro‐2,4‐dinitrobenzene (CDNB) was used as a substrate, butein exerted significantly more potent inhibition on the cationic isoforms C‐2, C‐3 and C‐4 with IC50 values of 6.8, 8.5 and 8.0 μM respectively. All the isoforms showed lower activity towards p‐nitrobenzyt chloride when compared to CDNB and inhibition of the p‐nitrobenzyl chloride‐activity by tannic acid and butein was also weaker. The inhibitory effects of tannic acid and butein on each isoform decreased generally with increasing pH in the range of 6.0 to 8.0. The optimum pHs for inhibitions by tannic acid and butein on the six individual isoforms lie in the pH range of 6.0 to 6.5.