Time-resolved surface-enhanced IR-absorption spectroscopy of direct electron transfer to cytochrome c oxidase from R. sphaeroides.

ABSTRACT

Time-resolved surface-enhanced IR-absorption spectroscopy triggered by electrochemical modulation has been performed on cytochrome c oxidase from Rhodobacter sphaeroides. Single bands isolated from a broad band in the amide I region using phase-sensitive detection were attributed to different redox centers. Their absorbances changing on the millisecond timescale could be fitted to a model based on protonation-dependent chemical reaction kinetics established previously. Substantial conformational changes of secondary structures coupled to redox transitions were revealed.