Isolation and characterization of a thymic factor.

A protein was isolated from bovine thymus that was shown to accelerate the appearance of hemolysin to sheep erythrocytes in neonatal mice. The isolation procedure consisted of saline homogenization, ammonium sulfate precipitation, and methanol precipitation, followed by chromatography on diethylaminoethyl-cellulose and two chromatographies on Sephadex G-150. The protein was shown to be homogeneous by polyacrylamide gel electrophoresis and by sedimentation velocity and sedimentation equilibrium analytical ultracentrifugation. The molecular weight was determined to be 79,950. Additional physical and chemical characteristics were also determined.