Isolation and structure of pro-methionine-enkephalin: Potential enkephalin precursor from porcine hypothalamus

Isolation and structure of pro-methionine-enkephalin: Potential enkephalin precursor from porcine hypothalamus

Endocrine and Polypeptide Laboratory, Veterans Administration Medical Center, New Orleans, Louisiana 70146
Department of Medicine, Tulane University School of Medicine, New Orleans, Louisiana 70146

Abstract

A hexapeptide that we have named pro-methionine-enkephalin has been isolated from acid extracts of porcine hypothalami and found to have the amino acid sequence H-Tyr-Gly-Gly-Phe-Met(O)-Arg-OH. This peptide is not a fragment of either porcine β-lipotropin or β-endorphin, which suggests that it could be a precursor of [Met]enkephalin in the brain by a pathway differing from the one usually postulated. The existence of still larger precursors of [Met]enkephalin, perhaps related to the recently reported α-neo-endorphin, is strongly implied by these studies. Synthetic H-Tyr-Gly-Gly-Phe-Met-Arg-OH exhibited low, but significant, opiate activity in vitro.