title: Identification and Characterization of Novel Antioxidant Peptides Involved in Redox Homeostasis of Frog, Limnonectes fragilis.
abstract: Previous studies have proved that a novel antioxidant system composed of various antioxidant peptides (AOPs) exists in the skin of ranid frogs, keeping the redox homeostasis. However, only a small number of AOPs have been identified so far. Here, a total of 47 cDNA sequences encoding 21 different AOPs belonging to 11 families were cloned from the skin cDNA library of Limnonectes fragilis. Among them, fragilin-A1 (VKRRGQDCIHGFCSD) and fragilin-B1 (GQFNDKRWIPFG) were also purified from skin secretions. They were selected with odorranain-Q-Lf (APIRMWYMYRKLTDMEPKPVA), the newest sequence among all 21 AOPs, to evaluate the antioxidant activities by direct free radical scavenging and lipid peroxidation inhibition assay. Results demonstrated that all peptides possessed strong DPPH and ABTS(.+) scavenging activities, and effectively inhibited lipid peroxidation in linoleic acid emulsion system during a 7- day test. No cytotoxic and hemolytic activity against human erythrocytes was observed for the three AOPs. The homology modeling analysis revealed that they all adopt tertiary structures ideally suited for the key residues to come into contact with the radicals. Current results reveal the existence of antioxidant system constituted of AOPs in the skin of the L. fragilis, and furthermore provide excellent templates for the development of novel antioxidant agents.
authors.affiliation: Institute of Marine Biological technology, School of Life Science and Biotechnology, Dalian University of Technology, Dalian, Liaoning 116024, China. yuhaining@dlut.edu.cn.
authors.forename: Haining
authors.initials: H
authors.lastname: Yu
authors.forename: Xue
authors.initials: X
authors.lastname: Qiao
authors.forename: Jiuxiang
authors.initials: J
authors.lastname: Gao
authors.forename: Chen
authors.initials: C
authors.lastname: Wang
authors.forename: Shasha
authors.initials: S
authors.lastname: Cai
authors.forename: Lan
authors.initials: L
authors.lastname: Feng
authors.forename: Hui
authors.initials: H
authors.lastname: Wang
authors.forename: Yi-Peng
authors.initials: YP
authors.lastname: Wang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000975:Antioxidants / Q000737:chemistry* / Q000494:pharmacology*; D001001:Anura / Q000502:physiology*; D004912:Erythrocytes / Q000187:drug effects; D006461:Hemolysis / Q000187:drug effects; D006706:Homeostasis; D006801:Humans; D015227:Lipid Peroxidation / Q000187:drug effects; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction / Q000187:drug effects; D010455:Peptides / Q000737:chemistry* / Q000494:pharmacology*; D011487:Protein Conformation; D016415:Sequence Alignment
chemical_list: D000975:Antioxidants; D010455:Peptides