Recombination kinetics following nanosecond laser photolysis of carbonmonoxyhaemogloblin.

The kinetics of the ultrafast ligand recombination following 347 nm laser photolysis of aqueous solutions of carbonmonoxyhaemogloblin have been investigated. The process is biphasic and the rate constants for the two processes as functions of temperature have been used to give activation energies of 6 +/- 3.9 kJ . mol-1 for the fast process and 31 +/- 4.8 kJ . mol-1 for the slow process. Frequency factors have also been calculated. The two processes are discussed in relation to both low-temperature studies and model calculations on the rate of entry of carbon monoxide into haem proteins.