Comparison of biochemical properties of liver arginase from streptozocin-induced diabetic and control mice

Zoltan Spolarics, Judith S. Bond

Research output: Contribution to journalArticle

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Abstract

Arginase activity is elevated in livers of diabetic animals compared to controls and there is evidence that this is due in part to increased specific activity (activity/mg arginase protein). To investigate the molecular basis of this increased activity, the physicochemical and kinetic properties of hepatic arginase from diabetic and control mice were compared. Two types of arginase subunits with molecular weights of 35,000 and 38,000 were found in both the diabetic and control animals and the subunits in these animals had similar, multiple ionic forms. Kinetic parameters of purified preparations of arginase for arginine (apparent Kmand Vmax values) and the thermal stability of these preparations from diabetics and controls were also similar. Furthermore, no difference was found in the distribution of arginase activity among different subcellular liver fractions. Separation of basic and acidic oligomeric forms of arginase by fast-protein liquid chromatography resulted in a slightly different distribution of activity among the forms in the normal and diabetic group. The apparent Km values for Mn2+ of the basic form of the enzyme were 25 and 33 μm for the enzyme from normal and diabetic animals, respectively; for acidic forms, for which two apparent Km values were measured, the values were 8 and 197 μm for arginase from controls and 35 and 537 μm from diabetics. These results indicate that in diabetes, while no marked changes in the physicochemical characteristics of arginase are obvious, some changes are found in the interaction of arginase with its cofactor Mn.

Original languageEnglish (US)
Pages (from-to)426-433
Number of pages8
JournalArchives of Biochemistry and Biophysics
Volume274
Issue number2
DOIs
StatePublished - Nov 1 1989
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Biochemistry
  • Molecular Biology

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