ISOLATION AND CHARACTERIZATION OF ALPACA GROWTH HORMONE

A simple and mild procedure is described for the isolation of pituitary growth hormone from alpaca glands. It involves extractions in buffer at pH 8. 7 and gel filtration in Sephadex G‐75. An average yield of 1 mg purified product may be obtained from 1 g fresh alpaca pituitary glands. The alpaca hormone was exam ined for homogeneity by SDS‐polyacrylamide gel electrophoresis, gel electro‐focusing and end‐group analyses. It is a protein composed of a single polypeptide chain with phenylalanine at both ends. The C‐terminal sequence is ‐Ala‐Phe. The molecular weight is approximately 21700 and the amino acid composition very similar to that observed in equine growth hormone.