Development Of Antimicrobial Peptide AWRK6 And Its Structure And Fuction

Antibacterial peptide(ABP)is a biological organism in the fight against exogenous pathogens,which expressed by immune defense systems of all kinds of organism to resist pathogen and malignant cells.Antibacterial peptide is a small molecule peptide generally containing amino acids from 10-50,with the features of broad-spectrum antibacterial activity,strong thermal stability,small molecular weight and immunogenicity and the bacteria difficult to produce resistant,so it has expected to be developed as a new antibacterial product.Previously,we isolated and identified the novel antimicrobial peptides,dybowskin2-CDYa(Dy2),in skin secretion from the Chinese frog R ana Dybowskii.Because of its instability,we need to modify it further.In this study,we tried to develop the modified Dy2,called AWRK6,by replacing few amino acids for the enhanced stability and hydrophobicity and to characterize their antimicrobial activities in various conditions.Peptides were synthesized using solid-phase synthesis protocol and their antimicrobial activities and kinetics were evaluated by MIC and CFU assay against Gram-positive and Gram-negative bacteria under physiological conditions.AWRK6 showed more potent antimicrobial activity than Dybowskii(2-4 fold)against most tested bacteria strains and also exhibited faster killing activity.Under physiological pH conditions,both peptides showed potent antimicrobial activities in alkaline environments.Also,the secondary structures of peptides were assessed by CD spectroscopy to examine the pH-dependent conformational changes.AWRK6 had higher organized secondary structure as the pH become alkaline.The protease susceptibility of peptides to trypsin was evaluated using SDS-PAGE.The modified peptide,AWRK6,was relatively resistant to degradation by trypsin than Dy2.This study suggests that AWRK6 would have more competitiveness in anti-infective drug's development.As this study shown,our new peptide AWRK6 has better development to become the prospect of the clinical medicinal.