TY - JOUR T1 - Characterization of an Endogenous Morphine-like Factor (Enkephalin) in Mammalian Brain JF - Molecular Pharmacology JO - Mol Pharmacol SP - 504 LP - 513 VL - 12 IS - 3 AU - GAVRIL W. PASTERNAK AU - RABI SIMANTOV AU - SOLOMON H. SNYDER Y1 - 1976/05/01 UR - http://molpharm.aspetjournals.org/content/12/3/504.abstract N2 - Mammalian brain extracts contain a substance, "enkephalin," which competes for opiate receptor binding in a highly selective fashion. This material behaves in opiate receptor assays as an opiate agonist, with its effects enhanced by manganese and decreased by sodium. The regional distribution of enkephalin parallels that of the opiate receptor itself. Enkephalin activity is degraded by carboxypeptidases A and B and leucinaminopeptidase as well as by chymotrypsin, but is resistant to trypsin and neuraminidase. Thus enkephalin appears to be a peptide. Gel filtration experiments indicate a molecular weight of about 1000. ER -