Human somatotropin: biological characterization of the recombinant molecule.

The recombinant hormone obtained by non-covalent interaction of the NH2-terminal 134 amino acid fragment with the COOH-terminal 51 amino acid fragment of the reduced-carbamidomethylated human somatotropin molecule is found to exhibit nearly full biological activity of the native hormone, as evidenced by the stimulation of hepatic ornithine decarboxylase (L-ornithine carboxy-lyase, EC 4.1.1.17) in vivo and protein synthesis in mouse mammary gland in vitro. Radioimmunoassay data indicate that the recombinant behaves immunochemically in a manner almost identical to that of the native hormone.