Role of the N-terminus of glutathione in the action of yeast glyoxalase I

K. T. Douglas*, A. Al-Timari, C. D'Silva, D. I. Gohel

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

A number of S-substituted glutathiones and the corresponding N-substituted S-substituted analogues have been found to be linear competitive inhibitors of yeast glyoxalase I at 26 degrees C over the pH range 4.6-8.5. N-Acetylation of S-(p-bromobenzyl)glutathione weakens binding by 13.7-fold. N-benzoylation by 25.6-fold, N-trimethylacetylation by 53.3-fold and N-carbobenzoxylation by 7.8-fold, indicating a minor steric component in the binding at the N-site. The Ki-weakening effect of N-substitution of glutathione depends on the chemical nature of the S-substituent, indicating flexibility in the glutathione and/or glyoxalase I contributions to the binding site for glutathione derivatives. The effect of N-acylation on Ki is in accord with a charge interaction of the free enzyme with S-blocked glutathione in a region of reasonably high dielectric constant. There is a slight pH effect on Ki for S-(m-trifluoromethylbenzyl)glutathione but not for S-(p-bromobenzyl)glutathione.

Original languageEnglish
Pages (from-to)323-329
Number of pages7
JournalThe Biochemical Journal
Volume207
Issue number2
DOIs
Publication statusPublished - 1 Nov 1982

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