Effects of Peptide Immobilization Sites on the Structure and Activity of Surface-Tethered Antimicrobial Peptides

Abstract

Antimicrobial peptides, because of their unique structural and chemical properties, hold a promising future for the development of a new class of bacterial-resistant antibiotics, effective antimicrobial coatings, and high performance biosensors. To understand the structure/function relationship of surface-bound peptides as they relate to such applications, sum frequency generation (SFG) vibrational spectroscopy, coarse grained molecular dynamics simulations, and antimicrobial activity tests were used to characterize both surface peptide structural information and peptide activity. Results from MSI-78, an antimicrobial peptide, chemically immobilized via the N- (nMSI-78) or C-terminus (MSI-78n), demonstrate that the attachment site influences the structure and behavior of surface-bound peptides. Although both immobilized peptides adopt an α-helical structure in aqueous buffer, nMSI-78 stands up and MSI-78n lies down on the surface, as indicated by both SFG and MD simulations. Antimicrobial activity tests indicated that peptides that stand up interact with bacterial cells much quicker than peptides that lie down. We believe that this study provides fundamental insights into how to rationally engineer peptides and substrate surfaces to produce optimized abiotic/biotic interfaces for antimicrobial applications and beyond.