[Isolation and certain properties of human pituitary prolactin]

A simple method of isolation of highly purified prolactin from acetonated preparations of anterior hypophysial lobes is described. The new method permits to obtain higher (about 10-fold) yields of the hormone, as compared to those obtained using previously described methods. Prolactin was extracted by acid aqueous acetone and was subsequently purified of extract by fractionation with acetone and NaCl and by isoelectric precipitation. The final stage of the hormone purification involved gel-filtration through Sephadex G-200; prolactin yield was 400 microgram per 1 hypophysis. The lactogenic activity of the hormone is 14 MU/mg; the sequence of N-terminal amino acid residues of prolactin is as follows: NH2-Leu-Pro-Ile-x-Pro-Leu(?)-Gly-Ala-.