A novel antimicrobial cyclic peptide, Brucyclin, was rationally designed from the original antibacterial plant peptide, Brucin. The chemically synthesized Brucyclin consists of amino acid sequence; (NH2- Gln-His-Thr-Leu-Cys-Met-Cys-Gly-Gly-Ala-Thr-Trp-COOH), with a molecular mass of m/z 1290. In the antimicrobial assay with 31 strains of pathogenic microorganisms, the peptide exhibited the most antimicrobial activity with a minimum inhibitory concentration (MIC) values ranging from 50-100 μg/ml against 2 strains of Gram-negative bacteria (Vibrio cholera non O1, non O139 and Klebsiella oxytoca), 1 strain of Gram-positive bacterium (Bacillus subtilis), and 1strain of yeast (Candida albicans), respectively. Structural analysis of Brucyclin indicated that it has a neutral charge with a hydrophobicity ratio of 50% and pI value of 6.72, respectively. The results from this study suggested that Brucyclin is a new antibiotic peptide that might be an alternative potent drug for treatment of various infectious diseases caused by pathogenic microorganisms.
Key words: antibacterial activity, antimicrobial peptide, Brucin, Brucyclin, cyclic peptide
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