Fig. 4.

The fraction of myoglobin molecules N(t) remaining unliganded at time t after CO photolysis. (a) rebinding of CO in a trehalose glass between 105 and 297 K [30]. The inset shows the activation enthalpy distribution that best fits the rate distribution (continuous lines) assuming 32 conformational substates. (b) Comparison of CO rebinding in trehalose glass and water [21]. The geminate yield is only about 4% because the escape of the CO from the protein is about 20-times faster than the geminate rebinding rate, so 96% of the photdissociated CO molecules rebind from the solvent in a bimolecular process, while in the trehalose glass all CO molecules remain in the protein to geminately rebind