Nmr Structural Studies of Antimicrobial Peptides, LPcin

Abstract

Lactophoricin (LPcin-I) is an antimicrobial, amphiphatic, cationic peptide with 23-amino acid residues isolated from bovine milk. Its analogous peptide, LPcin-II, lacks six N-terminal amino acids compared to LPcin-I. Interestingly, LPcin-II does not display any antimicrobial activity, whereas LPcin-I inhibits the growth of both Gram-negative and Gram-positive bacteria without exhibiting any hemolytic activity. Uniformly 15N-labeled LPcin peptides were prepared by the recombinant expression of fusion proteins in E. coli and their properties were characterized by mass spectrometry (MS), Circular dichroism (CD) spectroscopy, and antimicrobial activity tests. To understand the structure-activity relationship of these two peptides, they were studied in model membrane environments by a combination of solution and solid-state NMR spectroscopy. We determined the tertiary structure of LPcin-I and LPcin-II in the presence of DPC micelles by solution NMR spectroscopy. Magnetically aligned unflipped bicelle samples were used to investigate the structure and topology of LPcin-I and LPcin-II by solid-state NMR spectroscopy. We will also discuss about the LPCin-Analogs that have much more powerful antimicrobial activity and 800MHz home-built solid-state NMR probe for bilayers.[1] Protein Expression and Purification 65 (2009), 23 [2] Biophysical J 101 (2011) 1193.View Large Image | View Hi-Res Image | Download PowerPoint Slide