Inhibition of the hydrolytic and transpeptidase activities of rat kidney γ-glutamyl transpeptidase by specific monoclonal antibodies

Evgenia Bluvshtein, George A. Glass, Gloria Volohonsky, Margalit Yaakubowitz, Ella Harness, Nechama I. Smorodinsky, Albrecht Seidel, Heinz Frank, Pablo Steinberg, Avishay A. Stark*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Monoclonal antibodies (mAb) against the native form of rat kidney γ- glutamyl transpeptidase (GGT) were isolated by screening hybridomas with rat kidney brush-border membrane vesicles. They were directed against protein rather than sugar epitopes in that each recognized all GGT isoforms. All of them inhibited partially the enzyme activity of GGT. They were specific in that they inhibited the rat enzyme, but not the mouse or human enzyme. Kinetic analyses were carried out with free GGT and GGT-mAb complexes with D- γ-glutamyl-p-nitroanilide in the presence or absence of maleate, or in the presence or absence of alanine, cysteine, cystine or glycylglycine as γ- glutamyl acceptors. mAbs 2A10 and 2E9 inhibited the hydrolytic and glutaminase activities of GGT and had little effect on the transpeptidation activity of the enzyme, whereas mAbs 4D7 and 5F10 inhibited transpeptidation, but not hydrolytic or glutaminase activities. mAb 5F10 mimicked the effect of maleate on GGT, in that it inhibited transpeptidation, enhanced the glutaminase activity and increased the affinity of the donor site of GGT for acivicin. Such mAbs may be useful for long-term studies in tissue cultures and in vivo, and for the identification of GGT epitopes that are important for the hydrolytic and transpeptidase activities.

Original languageEnglish
Pages (from-to)844-854
Number of pages11
JournalEuropean Journal of Biochemistry
Volume260
Issue number3
DOIs
StatePublished - 15 Mar 1999

Keywords

  • Kinetic constants
  • Monoclonal antibodies
  • Transpeptidation
  • γ-glutamyl transpeptidase

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