Imaging surface structure of purple membrane partly dissolved by CHAPS with atomic force microscope

Atomic force microscope was employed to study the surface structure of purple membrane (PM) using contact mode in liquid. The surface structures of native PM and PM partly dissolved by detergent CHAPS were compared. Results show that 6 mmol/L CHAPS could induce some cracks and holes in PM. While Bateriorhodopsin (BR) was still presented as trimers in the two-dimensional hexagonal structure. We assume that it was caused by the interaction between CHAPS micellar and PM. Both absorption spectra and flash photolysis kinetic spectra indicated that BR's biochemical functions have been changed.