Isolation and characterization of a novel antibacterial peptide derived from hemoglobin alpha in the liver of Japanese eel, Anguilla japonica

We isolated and characterized a novel antibacterial peptide, AJHb alpha, derived from hemoglobin alpha in the liver of Japanese eel, Anguilla japonica. It with concentration of 11.30 mu M exhibited stronger antibacterial activity against pathogenic bacterium 1 x 10(6) cell ml(-1) Edwardsiella tarda than other two bacteria. The extraction procedure for AJHb alpha included extraction with acetate acid, ultrafiltration, cation-exchange chromatography on HiTrap (TM) CM FF, reverse-phase liquid chromatography on Source 5R RPC and 08 RP-HPLC. MALDI-TOF MS suggested that the peptide had an observed molecular weight of 2388.05 Da. Its amino acid sequence determined by Edman degradation was similar to those of hemoglobin alpha chain in other fish by BLAST analysis. A complete N-terminal amino acid sequence of the AJHba was FAHWPDLGPGSPSVKKHGKVIM corresponding to the cDNA sequence by RACE amplification. Its synthetic peptide had strong antibacterial activities against ten Gram-positive or negative bacteria. To our knowledge, AJHba was the first identified fragment of hemoglobin alpha chain with strong antibacterial activity in fish. (C) 2012 Elsevier Ltd. All rights reserved.