Peptides of the neurohypophysis.

Acetone powder of pig posterior pituitary tissue was used as starting material for isolation of peptides. Extraction of peptides was effected by percolation with a d1scontinous gradient of alcohol, acetic acid and water. Peptides in the percolates were fractionated by methods of gel filtration on Sephadex columns and ion-exchange chromatography on DEAE- and CM-Cellulose. Two major polypeptides, designated P-64 and P-32, were isolated in a highly purified state. Their molecular weights were estimated to be about 9,000. Their amino acid compositions were marked by high contents of cystine and glyc1ne but no histidine and tryptophan was found. The purified polypeptides were found to be devoid of oxytocic, pressor and fat-mobilizing activities. Both polypeptides bind lysine vasopressin. The amino acid sequences of some tryptic peptides resulted from polypeptide P-64 have also been worked out