High pressure spectroscopic and kinetic studies of ligand binding to myoglobin

Abstract

Raman and transient absorption spectroscopy are employed to probe structural and kinetic changes in CO binding to myoglobin at variable pressure and temperature. The shift of the iron-histidine mode with pressure observed in Raman measurements with resonance excitation for the vibrational modes associated with the active site is consistent with a conformational change, which alters the tilt angle between the heme plane and the proximal histidine and the out-of-plane iron position. Flash photolysis experiments in the time range 5×10−8 to 102 seconds monitoring the Soret absorption band show that the multistep kinetics show significant dependence on pressure.