벼 유래 글루타티온 전달효소에서 진화적으로 보존된 알지닌 18 잔기의 특성 연구

Abstract

Glutathione S-transferases (GSTs, EC 2.5.1.18) are a major family of detoxification enzyme that catalyzes the formation of conjugates between reduced glutathione (GSH). In order to clarify the role of the evolutionally conserved Arg 18 residue in rice phi class glutathione S-transferase (OsGSTF3), this residue was replaced with alanine by site-directed mutagenesis and the effects of the replacement on enzymatic properties were investigated. R18A mutant was expressed in Escherichia coli and purified to electrophoretic homogeneity by affinity chromatography on immobilized GSH. The replacement of Arg18 with alanine did not affect a specific activity for GSH-DNB conjugation reaction. The specific activity of R182T toward CDNB was 7.2 µmol/min/mg and approximately 92% of that of the residue in rice glutathione S-transferase does not seem to be directly involved in the catalytic mechanism, although the highly conserved residue is expected to be important for the structure and/or function of the enzyme.