Properties of thymidine kinase partially purified from human adrenal glands

Thymidine kinase was partially purified from human adrenocortical carcinoma, hyperplasia, and normal adrenal glands. For the purpose of clarifying the qualitative and quantitative difference of thymidine kinase between cancer and normal tissue, biochemical properties of partially purified thymidine kinase were compared. Adrenocortical carcinoma and hyperplasia contained greater concentration of thymidine kinase than normal adrenal gland. By the DEAE-cellulose chromatography, adrenocortical carcinoma gave two peaks (Peak I and Peak II) of thymidine kinase, while in hyperplasia and normal adrenal gland, the second peak (Peak II) was only slightly detected or hardly detected. Thymidine kinase in these three glands was identical with respect to pH optimum and inhibition by dTTP, but inhibition by dCTP was quite different. dCTP inhibited the activity of normal adrenal gland and Peak II of adrenocortical carcinoma by 55% and 40% at 0.1 mM, respectively, but the activity of adrenocortical hyperplasia and Peak I of adrenocortical carcinoma was hardly affected. Normal adrenal enzyme was more stable against heat inactivation than adrenocortical carcinoma and hyperplasia. The apparent Km with thymidine for Peak I and Peak II of adrenocortical carcinoma, hyperplasia, and normal adrenal gland was 5.0, 11.1, 5.1 and 25.0 x 10(-6)M, respectively.