ELECTROPHORETIC CHARACTERIZATION AND SUBCELLULAR-DISTRIBUTION OF HEXOKINASE ISOENZYMES IN RED BLOOD-CELLS OF RABBITS

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  • 1 January 1979
    • journal article
    • research article
    • Vol. 38  (8) , 1091-1099
Abstract
The isoenzyme pattern of hexokinase in rabbit red cells (erythrocytes, fetal erythrocytes and reticulocytes) were determined by means of agrose gel and disc electrophoresis. One duplicated hexokinase 4a and 4b according to the IUPAC[International Union of Pure and Applied Chemistry]-nomenclature) was detected in rabbit erythrocytes and described for human erythrocytes. Besides the isoenzymes, 4a and 4b reticulocytes also contained hexokinase 2 and 3 like rabbit and rat liver. The high Km glucose phosphorylating enzyme, hexokinase 1 could be demonstrated only under specific conditions in the reticulocytes during the initial stage of anemia. After the fractionation of reticulocyte homogenates the total hexokinase activity was recovered in the mitochondria and cytosol to nearly equal amounts as revealed by the distribution of markers. Hexokinase 2 and 3 were detectable in reticulocytes and in isolated mitochondria only after the addition of certain dissociating agents. In contrast to the tightly bound mitochondrial hexokinases 2 and 3, types 4a and 4b were more loosely bound and exhibited a bilocal distribution between mitochondria and cytosol of reticulocytes.