Tyrosine-7 in Human Class Pi Glutathione S-Transferase is Important for Lowering the pka of the Thiol Group of Glutathione in the Enzyme-Glutathione Complex
- Authors
- Kong, Kwang-Hoon; Takasu, Kazue; Inoue, Hideshi; Takahashi, kenji
- Issue Date
- Apr-1992
- Publisher
- ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS
- Citation
- BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS, v.184, no.1, pp 194 - 197
- Pages
- 4
- Journal Title
- BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS
- Volume
- 184
- Number
- 1
- Start Page
- 194
- End Page
- 197
- URI
- https://scholarworks.bwise.kr/cau/handle/2019.sw.cau/36793
- DOI
- 10.1016/0006-291X(92)91177-R
- ISSN
- 0006-291X
1090-2104
- Abstract
- Previously, we reported the importance of Tyr7 for the catalytic activity of human class Pi glutathione S-transferase [Kong et al. (1992) Biochem. Biophys. Res. Comm., 182, 1122]. As an extention of this study, we investigated the pH dependence of kinetic parameters of the wild-type enzyme and the Y7F mutant. The replacement of Tyr7 with phenylalanine was found to alter the pH dependence of Vmax and Vmax/KmCDNB of the enzyme for conjugation of GSH with 1-chloro-2,4-dinitrobenzene (CDNB). The pKa of the thiol of GSH in the wild-type enzyme-GSH complex was estimated to be about 2.4 pK units lower than that in the Y7F-GSH complex. Tyr7 is thus considered to be important for catalytic activity in lowering the pKa of the thiol of GSH in the enzyme-GSH complex.
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