HOLE-BURNING AND PRESSURE PHENOMENA IN CHROMOPROTEINS

We investigated the behavior of spectral holes under pressure at vario us frequencies within the inhomogeneous band for two proteins, namely myoglobin and horseradish peroxidase. In order to achieve narrow bandw idth 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 f ashion, when the burn-frequency was tuned across the absorption band. In horseradish peroxidase the pressure shift was linear with burn-freq uency but changed in a dramatic fashion upon complex formation with a substrate molecule. These observations are interpreted within the fram e of the so-called correlated phase space model.