[Catalytic properties and isoenzyme composition of hexokinase in thyroid gland normal and neoplastic tissue]

Catalytic properties and isoenzyme composition of hexokinase were studied in extracts of normal thyroid, thyroid benign adenoma and thyroid carcinoma tissues from 23 patients. It was shown that the "cancer" hexokinase was several times more active and had lower Km (glucose) as compared with the enzyme from normal thyroid and benign tumor. Gel electrophoretic study revealed five hexokinase isoenzymes in both normal thyroid and its benign tumor. The hexokinase isoenzyme pattern in thyroid carcinoma was characterized by the "deletion" or distinctly decreased ratio of the "slowest" component. Studies on catalytic properties and isoenzyme composition of hexokinase are important as an additional test for the differentiation between benign and malignant tumors.