In Situ Mapping of Membranolytic Protein-membrane Interactions by Combined Attenuated Total Reflection Fourier-transform Infrared Spectroscopy-atomic Force Microscopy (ATR-FTIR-AFM)

• Main Author: Edwards, Michelle
• Other Authors: Yip, Christopher M.
• Language: en_ca
• Published: 2011
• Subjects: atomic force microscopy; infrared spectroscopy; protein-membrane interactions; peptide-membrane interactions; sticholysin; cationic antimicrobial peptide; 0786; 0541
• Online Access: http://hdl.handle.net/1807/30585

A combined attenuated total reflection-Fourier-transform infrared spectroscopy (ATR-FTIR)-atomic force microscopy (AFM) platform was used to visualize and characterize membranolytic protein- and peptide-membrane interactions, allowing spectroscopic details to be correlated with structural features. Modifications to a previous combined platform permitted IR results for physiologically-relevant protein or peptide concentrations as well as provided nanometer-resolution height data for AFM. This combination provides greater insight than individual techniques alone. The interactions of hemolytic sticholysin proteins on a model red blood cell membrane showed evidence of conformational changes associated with a membrane-induced organization. In addition, the examination of a de novo cationic antimicrobial peptide on a model bacterial membrane showed that the peptide adopted a helical structure upon interaction with the membrane, and also provided evidence of membrane disruption and peptide aggregation. These results demonstrate that ATR-FTIR-AFM can be a powerful tool for understanding protein- and peptide-membrane interactions.