GEMINATE RECOMBINATION OF DIATOMIC LIGANDS CO, O-2 AND NO WITH MYOGLOBIN

The kinetics of geminate recombination of horse heart myoglobin with t he diatomic ligands carbon monoxide, dioxygen, and nitric oxide have b een reexamined. The new measurements are distinguished from previous s tudies by (1) consideration of the complete time range longer than 1 p s, (2) inclusion of the effect of temperature changes near ambient, (3 ) attention to the relation between recombination kinetics and the yie ld of dissociated partners on the millisecond time scale, and (4) use of singular value decomposition in the analysis. These picosecond resu lts, together with earlier nanosecond data, for O-2 prove that models incorporating one, two, or even three discrete intermediates are not s ufficient to account for all features of geminate recombination kineti cs. Instead, a continuous evolution of the geminate pair distribution is preferred.