Bovine transforming growth factor beta. Purification and characterization.

Polypeptide growth factor isolated from bovine platelets was classified on the basis of its physico-chemical and biological properties to be transforming growth factor type beta (TGF beta). This growth factor was completely purified from platelet lysate by acid ethanol extraction, Bio-Gel P-60 filtration, ion-exchange chromatography on CM-Sephadex followed by two successive gel filtrations on Bio-Gel P-10 and Sephadex G-100. After the last gel filtration over 35,000-fold purified TGF beta was obtained. The purity of the preparation was confirmed by SDS-polyacrylamide gel electrophoresis, which revealed a single protein band with Mr of 25,000-27,000. Further studies showed that native TGF beta consists of two Mr 13,000 polypeptide chains held together by disulfide bonds.