ACTIVATION OF THE COLLAGEN-BINDING OF ENDOGENOUS SERUM VITRONECTIN BY HEATING, UREA AND GLYCOSAMINOGLYCANS

The present study describes that the collagen-binding activity of vitronectin in human serum increases by treatment with heparin, heating and urea. Vitronectin purified from human serum was bound to native collagen, whereas endogenous vitronectin in the serum was not. We have examined the conditions to change the collagen-binding activity of endogenous vitronectin. Endogenous vitronectin in human serum became considerably bound to collagen when the serum was boiled in 4-8 M urea for 5 min and mixed with heparin (0.5-5-mu-g/ml). Each treatment of heating, urea or heparin alone, and any combination of the two factors, inefficiently activated the binding. Dextran sulfate could substitute for heparin, but dermatan sulfate, keratan sulfate, chondroitin sulfate A and C, heparan sulfate and hyaluronan could not. Possible explanations for the activation of endogenous vitronectin are discussed.