title: The oxidation metabolites of endomorphin 1 and its fragments induced by free radicals.
abstract: Endomorphin 1 (EM1), an endogenous micro-opioid receptor agonist, acts as a free radical scavenger in vitro and an antioxidant in vivo. The modification of EM1 by ROS and the properties of the OM attracted our attention. In vitro assays were performed via RP-HPLC, spectrophotometric measurements, EPR and amino acid analysis, Schmorl's reaction to define the formation of melanin-like compounds transformed from EM1, collectively named EM1-melanin and by solubility assay, radioligand-binding assay, NADH oxidation, superoxide anion scavenging assay to study some physical and chemical properties of EM1-melanin. Possible pathways of the formation of EM1-melanin were proposed.
authors.affiliation: School of Life Science and State Key Laboratory of Applied Organic Chemistry, School of Basic Medical Sciences, Institute of Biochemistry and Molecular Biology, Lanzhou University, Lanzhou 730000, China.
authors.forename: Pin
authors.initials: P
authors.lastname: Gong
authors.forename: Fu Xin
authors.initials: FX
authors.lastname: Chen
authors.forename: Qianyu
authors.initials: Q
authors.lastname: Zhao
authors.forename: Guo Fen
authors.initials: GF
authors.lastname: Ma
authors.forename: Rui
authors.initials: R
authors.lastname: Wang
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals / Q000737:chemistry* / Q000378:metabolism*; D008297:Male; D009243:NAD / Q000737:chemistry / Q000378:metabolism; D009842:Oligopeptides / Q000737:chemistry* / Q000378:metabolism*; D010084:Oxidation-Reduction; D051381:Rats; D017208:Rats, Wistar
chemical_list: D005609:Free Radicals; D009842:Oligopeptides; C105293:endomorphin 1; D009243:NAD