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

Abstract
.beta.-Endorphin was isolated from 200 rat pituitaries by means of high-performance column chromatography, using sensitive fluorometric methods and a radioreceptor assay for opioid activity. The .beta.-endorphin was characterized as to molecular weight, amino acid composition and mapping of tryptic peptides by a new microtechnique. Rat .beta.-endorphin is identical to camel and sheep .beta.-endorphin. .alpha.-Endorphin, Met-enkephalin, a nonpeptide morphine-like compound (MLC), and an additional unidentified opioid compound were detected in the extract of rat pituitary.