Sequence - activity relationship study of the antibacterial peptide (aurein1/2) and its analogs

Aurein 1/2 is a 13-residue peptide with a vast antimicrobial and anticancer activity. Two- dimensional NMR spectroscopy of peptide solubilized in the 70% TFE (2, 2, 2-Trifluoroethanol) indicated an alpha-helical conformation. The mechanism of its action is not yet fully recognized. This study was designed to improve the antimicrobial activity and relationship between subsequence-activity in Aurein 1/2 and its analoges. Analogs of this peptide were designed and synthesized. Methods and Materials: The G1F3/RW and F3W analogs and retro - analog were synthesized with solide phase and purified via HPLC and lyophilized. These analogs were assayed by several amino acid analysis, HPLC, and electrospray mass spectrometry. Then antimicrobial activity of the peptides was assessed by using the standard microdilution susceptibility test. The data demonstrated that G1F3/RW analog had a higher activity and results of test figure of minimum inhibitory concentration for F3W analog had three levels. But the native, F3W analog and retro-analog was inactive. The higher activity of G1F3/RW in compare to F3W may be related to the positive charge of Arg that leading stronger interaction with the negative charges on the membrane surface. The result showed that reversed direction of aurein 1/2 significantly effects on activity of the peptide. It is also suggested inactivation of reto-analog amino acid type, position and size should be cautious for peptides designed as drug because it may be effect to control dimerization and maintenance of antimicrobial activity of the peptide.