HOLE-BURNING AND PRESSURE PHENOMENA IN CHROMOPROTEINS

We investigated the behavior of spectral holes under pressure at various frequencies within the inhomogeneous band for two proteins, namely myoglobin and horseradish peroxidase. In order to achieve narrow bandwidth hole burning, the heme chromophore was replaced by protoporphyrin IX and mesoporphyrin IX, respectively In myoglobin, we found that the pressure induced shift of the holes varied in a strongly non-linear fashion, when the burn-frequency was tuned across the absorption band. In horseradish peroxidase the pressure shift was linear with burn-frequency but changed in a dramatic fashion upon complex formation with a substrate molecule. These observations are interpreted within the frame of the so-called correlated phase space model.