Further characterization of morphine-like peptides (endorphins) from pituitary

Pituitary peptides with opioid pharmacologic action (endorphins) can exist in several forms with different basicities and molecular weights from about 3000 to less than 1000 daltons. Partial purification yielded an endorphin at least 4 times more potent than normorphine and 16 times more potent than the endogenous brain pentapeptide methionine enkephalin. It is proposed that pituitary endorphin or a similar peptide in brain may be the precursor of brain enkephalin.