SOME PROPERTIES OF MITOCHONDRIAL AND CELL SAP ALANINE AMINOTRANSFERASE OF RAT-HEART

  • 1 January 1976
    • journal article
    • research article
    • Vol. 25  (3) , 223-230
Abstract
Alanine aminotransferase activity was present in mitochondria and the cell sap fraction of the rat myocardium. As distinct from the cell sap form, mitochondrial alanine aminotransferase was significantly inhibited by Cl-, maleate and incubation medium temperatures of over 40.degree. C. Activity of the cell sap enzyme was inhibited by phosphate and stimulated by temperatures of over 40.degree. C. The pH optimum for cell sap alanine aminotransferase was in the region of 8, while for the mitochondrial enzyme it had a wider range (pH 7.3-8.2). D,L-Penicillamine, a vitamin B6 antagonist, inhibited alanine aminotransferase activity equally in intact and tritonized mitochondria and in the cell sap fraction. The activity of mitochondrial and cell sap alanine aminotransferase rose in correlation to the stage of ontogenesis, with the maximum increase in the cell sap fraction 14-20 days after birth. The addition of coenzyme to the incubation medium did not affect the activity of either mitochondrial or cell sap alanine aminotransferase. There are probably 2 different alanine aminotransferase enzymes in the rat heart, with different intracellular localizations and probably with different regulative functions.

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