Brucin, a specific antibacterial peptide against Strep. pyogenes was chemically synthesized and its amino acid sequence, NH2-His-Thr-Leu-Cys-Met-Asp-Gly-Gly-Ala-Thr-Tyr, was modified to improve the antibacterial activity. Only one from five-modified peptides with the sequence NH2-His-Thr-Leu-Cys-Met-Gly-Lys-Ala-Thr-Tyr possessed the antibacterial activity and it was designated as M-Brucin. Structural analysis of M-Brucin indicated that it was a linear with random coil peptide with a molecular mass of 1248.43 Da. It was a positive charge peptide (net charge = +1) with a pI value of 8.21 and hydrophobicity ratio of 40 %. The positive antimicrobial effect of M-Brucin was tested by agar dilution technique against 30 human-pathogenic bacteria and 1 fungus. Its inhibitory activity was tested against Staph. epidermidis and Streptococcus pyogenes DMST 17020 with IC50 values of 225 µM and 250 µM, respectively. Moreover, its inhibitory activity was identified as being as strong as penicillin G and chloramphenicol, with no toxicity to normal Vero cell at the same concentration tested. The results suggest that MB may be further developed as an alternative drug for the treatment of the disease caused by Strep.
Key words: M-Brucin, Brucin, antibacterial activity, Strep. pyogenes, Staph. epidermidis
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