COMBINATION OF POTENTIOMETRY AND RESONANCE RAMAN-SPECTROSCOPY FOR THEANALYSIS OF A REDOX PROTEIN

This paper describes apparatus and procedures for combining resonance Raman and optical absorption spectroscopies with potentiometry for the study of redox-active heme proteins. A specially designed anaerobic t itration cell is described which allows for the laser excitation of th e sample and the monitoring of both Raman scattered light and directly transmitted light from an optical source. New procedures for utilizat ion of A/D and D/A converters on a standard I/O computer card are desc ribed, which allow for computer-controlled potentiometry and coulometr y. The system was tested with cytochrome c, a well-characterized respi ratory protein. The correct values for the midpoint potential and elec tron number of the Nernst equation were obtained both by the optical a bsorption and resonance Raman measurements. (C) 1995 Academic Press, I nc.