Isolation and Characterization of the S-Carboxymethyl Heavy Chain Derivative of Human Plasmin

The S-carboxymethyl heavy chain derivative of human plasmin was prepared in a highly purified form by precipitating out the contaminating S-carboxymethyl light chain derivative in 1 m trichloracetic acid-8 m urea. The S-carboxymethyl heavy chain derivative was shown to be homogeneous by ultracentrifugal, carboxyl-terminal amino acid, and cellulose acetate electrophoretic analyses. Its weight average molecular weight was determined to be 48,800 ± 3,000 and its sedimentation coefficient was determined to be 2.8 S. Arginine was verified to be its carboxyl-terminal amino acid. The heavy chain derivative consists of approximately 410 amino acid residues.