Noninvasive Auto-Photoreduction Used as a Tool for Studying Structural Changes in Heme-Copper Oxidases by FTIR Spectroscopy

AbstractWe demonstrate an efficient Fourier transform infrared (FTIR) spectroscopic method, termed “auto-photoreduction,” that uses anaerobic photo-induced internal electron transfer to monitor reaction-initiated changes of heme-copper oxidases. It can be applied without the use of either expensive electrochemical equipment, or caged compounds, which cause significant background signals. At high irradiation power, carbon monoxide is released from high-spin heme a of cytochrome c oxidase and heme o from cytochrome bo3. Photochemistry is initiated at wavelengths