Isolation and Characterization of Mink Growth Hormone

Growth hormone (GH) was isolated from the pituitary gland of the mink (Mustela vison) and characterized biochemically and immunologically. Mink GH was extracted under alkaline conditions after defatting the tissue with acetone. A GH having a molecular weight of 22Kd via sodium dodesyl sulfate gel electrophoresis was purified by ion-exchange chromatography on DE-52, ammonium sulfate precipitation, gel filtration on Sephadex G-75 and reverse phase high-performance liquid chromatography on ODS-120T. An isoelectric point of 6.9 for the protein was estimated by gel electrofocusing. Amino acid composition of the GH was similar to those of other mammalian GHs. The amino-terminal amino acid sequence, a total of 34 residues, was determined by analyzing the intact protein. Sequence comparison revealed that the mink 22Kd was homologous to other mammalian GHs. Moreover, the mink protein showed competitive inhibition curves parallel to bovine GH via radioimmunoassay using ovine GH antiserum.