Purification and characterization of one novel cationic antimicrobial peptide from skin secretion of Bufo kavirensis

Objective: Antimicrobial peptides are the most important agents in innate immune system. These peptides have suitable activities against different pathogens. The aim of this study was to purify new antimicrobial peptides from skin secretion of Bufo kavirensis. Material and Methods: Purification of peptides was carried out by reverse phase-HPLC and its sequence was determined by using MS/MS. The antimicrobial activity was tested by Radial Diffusion Assay (RDA) and Minimal Inhibitory Concentration (MIC) methods. Results: This peptide is composed of 20 amino acids with the sequence of: ILGPVLGLVGRLAGGLIKRE. There is no similarity between this new and novel peptide which is named Maximin Bk and other antimicrobial peptides. The Maximin Bk showed considerable antimicrobial activity against gram positive and gram negative bacteria (Minimum Inhibitory Concentrations (MIC 8.1 to 20.78 µg/ml) as well as fungi (MIC, 25.7 to 35.6 mg/ml). Buforin -K showed virtually low hemolytic activity, 5% hemolysis in a concentration of 100 μg/mL. Conclusion: The new antimicrobial peptide from skin secretion of Bufo kavirensis showed higher antimicrobial activity against gram negative than against gram positive bacteria and fungi. In base of high antimicrobial and low hemolytic activity, Maximin Bk is the potent peptide for treatment of various microbial diseases.