[Binding of butocin to serum proteins (author's transl)].

The binding of N-[-5-(6-purinylthio)-valeryl]-glycin ethylester (butocin, PVG) to serum proteins and pure human albumin was studied using the method of equilibrium dialysis. Its binding to protein in sera diluted 1:1 of 10 patients with malignant disease averaged 48.4 +/- 7.07%. At the butocin concentration of 20 micrograms/ml an average of 36% of butocin were bound to pure albumin. Only a small portion was bound to globulin fractions. Measurements of the saturation curve showed butocin to be bound to albumin molecule by one binding centre with a microscopic association constant kappa = 1.7 . 10(3) mol/l.