Isolation and characterization of the opioid peptides from rat pituitary: beta-lipotropin

Rat beta-lipotropin was isolated from 40 anterior pituitaries using high efficiency chromatography columns and sensitive fluorometric methods. The beta-lipotropin was characterized as to molecular weight, amino acid composition, and generation of opioid activity by trypsinization. Other opioid peptides, as well as a precursor to opioid peptides with a molecular weight larger than that of beta-lipotropin, were observed in this tissue.