Human glutathione S-transferases. The H(a) multigene family encodes products of different but overlapping substrate specificities

N. W.I. Chow, J. Whang-Peng, C. S. Kao-Shan, M. F. Tam, H. C.J. Lai, C. P.D. Tu

研究成果: 雜誌貢獻文章

27 引文 斯高帕斯(Scopus)

摘要

The human glutathione S-transferase cDNAs encoding subunits 1 and 2 contain intrinsic ribosome-binding sites in their 5'-untranslated regions for direct expression in Escherichia coli. We show that functional human GSH S-transferases 1-1 and 2-2 are synthesized from λGTH1 and λGTH2 in phage lysates of E. coli Y1090, in lysogens of E. coli Y1089, and from the plasmid expression constructs in pKK223-3. The E. coli-expressed human GHS S-transferases 1-1 and 2-2 do not have blocked N termini in contrast to those directly purified from human livers. These two isozymes, with 11 amino acid substitutions between them, are similar in their K(m) values for GSH and 1-chloro-2,4-dinitrobenzene and K(cat) values for this conjugation reaction. The human GSH S-transferase 2-2, however, is a more active GSH peroxidase than transferase 1-1 toward cumene hydroperoxide and t-butyl hydroperoxide. Our results indicate that different members of a GSH S-transferase gene family with limited amino acid substitutions have different but overlapping substrate specificities. We propose that accumulation of single amino acid replacements may be an important mechanism for generating diversity in GSH S-transferases with various xenobiotic substrates. In situ chromosomal hybridization results show that the GSH transferase H(a) genes are located in the region of 6p12.
原文英語
頁(從 - 到)12797-12800
頁數4
期刊Journal of Biological Chemistry
263
發行號26
出版狀態已發佈 - 一月 1 1988
對外發佈Yes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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