Changes in the kinetic parameters of hepatic γ-glutamyltransferase from streptozotocin-induced diabetic rats

Paul D. Cornwell, John B. Watkins

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7 Scopus citations

Abstract

Previous research has shown that the enzymatic activity of hepatic γ-glutamyltransferase was increased in streptozotocin-induced diabetic rats with no increase in the expression of the protein. The current work has characterized the differences in the kinetic properties of hepatic γ-glutamyltransferase from diabetic versus control rats. Hepatic γ-glutamyltransferase was purified from control male and female rats and from rats made diabetic 30 days previously with streptozotocin. The maximal velocity and the Michaelis constant were determined for the purified enzyme with two separate donors (L-γ-glutamyl-p-nitroanilide or L-γ-glutamyl-(7-amido-4-methylcoumarin)) in the presence of one of eight acceptors (L-alanine-glycine, L-glycine-glycine, L-methionine, L-glutamate, L-alanine, L-glutamine, L-phenylalanine or L-aspartate). With both donors, hepatic γ-glutamyltransferase from diabetic rats had a consistently higher kinetic efficiency than γ-glutamyltransferase from controls. The kinetic efficiency percent increase of diabetic over control γ-glutamyltransferase when averaged across all acceptors was higher in males than in females. With L-γ-glutamyl-p-nitroanilide, the kinetic efficiency increase of diabetic over control γ-glutamyltransferase was higher with poor acceptors than with highly efficient acceptors. These data indicate that there are differences in the physical properties of hepatic γ-glutamyltransferase from diabetic versus control rats and from female versus male rats.

Original languageEnglish (US)
Pages (from-to)184-191
Number of pages8
JournalBiochimica et Biophysica Acta - Protein Structure and Molecular Enzymology
Volume1545
Issue number1-2
DOIs
StatePublished - Feb 9 2001

Keywords

  • γ-Glutamyltransferase
  • Diabetes mellitus
  • Enzyme kinetics
  • Glycosidase
  • Glycosyltransferase
  • Streptozotocin

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Structural Biology
  • Biophysics

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