Design and NMR Structural Studies of New Antimicrobial Peptides with Higher Activity

Abstract

The availability of antibiotics has allowed for the successful treatment of many bacterial infections as well as the ability to perform invasive medical procedures including surgery and chemotherapy. However, their wide use has led to pathogens' increased drug resistance and the need to find novel classes of antimicrobial peptides as alternatives to antibiotics. Lactophoricin (LPcin), a cationic amphipathic peptide consists of 23-mer peptide, corresponds to the carboxy terminal 113-135 region of component-3 of proteose-peptone and is a good candidate as a peptide antibiotic because it has an antibacterial activity but no hemolytic activity. Three different analogs of LPcin, LPcin-yk2 which has mutant amino acids, LPcin-yk1 and LPcin-yk3 that has shorter mutant amino acids are recently developed by using peptide engineering techniques in our laboratory and show better antibioitic activities than wild-type LPcin and no toxicity at all. Recently, we designed and selected more antimicrobial peptides LPcin-YK5, LPcub-YK8 and LPcin-YK11 based on LPcin-YK3. Designed all analogues were expressed and purified using several biophysical techniques and characterized using antimicrobial activity tests and various spectroscopic methods like MALDI-TOF MS and CD spectrometry, as well as 1D/2D solution NMR and solid-state NMR techniques in membrane environments. In here, we will present the optimizing processes with high-yield expression and purification of new LPcin analogs and solid- state NMR structural studies to figure out antibacterial killing mechanisms.