Partial characterization of leucocyte alpha-glucosidase in late onset glycogenosis type II.
We describe partial characterization and properties of leucocyte alpha-glucosidase from a patient with clinical features intermediate of juvenile and adult onset forms of glycogenosis type II. Acid and neutral alpha-glucosidase activities toward 4-methylumbelliferyl glucopyranoside as substrate were studied in total leucocytes, and separately in lymphocytes and granulocytes. Lymphocytes, which showed markedly reduced activities of acid alpha-glucosidase in the patient, are the most reliable peripheral blood cells for the diagnosis of glycogenosis type II. Moreover, the ratio of acid/neutral alpha-glucosidase activities, especially in lymphocytes, is a useful parameter for the diagnosis. In lymphocytes, the Km values of both acid and neutral alpha-glucosidases were essentially the same between the patient and normal controls; the Vmax value of acid alpha-glucosidase from the patient was markedly reduced, and the Vmax value of neutral alpha-glucosidase from the patient was reduced by 36% as compared with that from normal controls. Heat-inactivation experiments revealed that acid alpha-glucosidase activities of lymphocytes were relatively heat-stable, while both acid and neutral alpha-glucosidases of granulocytes were heat-labile. No differences in these properties, however, could be detected between the patient and normal controls.
Kohriyama
T
T
Third Department of Internal Medicine, Kagoshima University School of Medicine, Japan.
Kuriyama
M
M
Hiwatari
R
R
Osame
M
M
Igata
A
A
D000328:Adult; D006009:Glycogen Storage Disease Type II / Q000201:enzymology*; D006358:Hot Temperature; D006801:Humans; D007962:Leukocytes / Q000201:enzymology*; D008297:Male; D000520:alpha-Glucosidases / Q000378:metabolism*
D000520:alpha-Glucosidases