Frog skins keep redox homeostasis by antioxidant peptides with rapid radical scavenging ability

The question of how amphibians can protect themselves from reactive oxygen species when exposed to the sun in an oxygen-rich atmosphere is important and interesting, not only from an evolutionary viewpoint, but also as a primer for researchers interested in mammalian skin biology, in which such peptide systems for antioxidant defense are not well studied. The identification of an antioxidant peptide named antioxidin-RL from frog (Odorrana livida) skin in this report supports the idea that a peptide antioxidant system may be a widespread antioxidant strategy among amphibian skins. Its ability to eliminate most of the 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) radical tested within 2 s, which is much faster than the commercial antioxidant factor butylated hydroxytoluene, suggests that it has a potentially large impact on redox homeostasis in amphibian skins. Cys10 is proven to be responsible for its rapid radical scavenging function and tyrosines take part in the binding of antioxidin-RL to radicals according to our nuclear magnetic resonance assay. (C) 2010 Elsevier Inc. All rights reserved.

We thank Chuck Cannon (Texas Tech University, USA); Zhenglong Gu, Roberto Flores, Shu-Bing Qian and Thomas Fox (Cornell University, USA) for their helpful comments and/or English editing on the manuscript. We are grateful to all members of CAS-Max Planck Junior Research Group for their help in the experiments and discussions during preparation of the manuscript. We also thank Jinqiu Zhou (Shanghai Institute for Biological Sciences, China) for providing yeast strains and Simon Newstead (Imperial College, United Kingdom) for the GFP-fusion plasmid. This work was supported by a CAS key grant (KSCX2-YW-N-060), two NSFC key grants (No. 30930056 and 30623007), a 973 Program (No. 2007CB815703-5), a CAS-Max Planck Society Fellowship, and the 100 Talent Program of CAS to W. W.