Biocytin-β-endorphin, human is abiotinylated β-Endorphin, human. β-Endorphin, human , a prominent endogenous peptide, existing in the hypophysis cerebri and hypothalamus, is an agonist of opioid receptor , with preferred affinity for μ-opioid receptor and δ-opioid receptor ; β-Endorphin, human exhibits antinociception activity.