Structure-activity relationship of buffalo antibacterial hepcidin analogs.

chemistry. CD spectroscopy revealed different spectra of the peptides in different solvents and in all the cases β-structure was found to be dominant with less α-helix as predicted. Quantitation of secondary structure indicated the highest β-structure for all the six peptides in SDS solution, when used as mimetic for membrane-like environment. The CD spectra of all the peptides taken in water showed that degree of randomness decreased with increase in chain length of the peptide. Out of the six peptides, only Hepc 1-25 , Hepc 6-25 and Hepc 7-25 showed antibacterial activity against Staphylococcus aureus (Gram-positive bacteria). The peptides did not show any sensitivity toward E. coli (Gram-negative bacteria). Minimum inhibitory concentration (MIC) showed the lowest value for Hepc 7-25 as an antibacterial agent, followed by Hepc 6-25 and Hepc 1-25 . The peptides Hepc 9-25 , Hepc 11-25 and Hepc 15-25 with more random structure did not show any antimicrobial activity The study demonstrated that 5 amino acids at N-terminal in buffalo hepcidin can be truncated without loss of antimicrobial activity and further reduction of length of the analog from 20 to 19 amino acids resulted increase in the activity because of increase in �-structure of the peptide shown by CD spectroscopy.