Kinetics of carbon monoxide binding to fully and partially reduced human hemoglobin valency hybrids

The kinetics of carbon monoxide binding following fast reduction of the valency hybrids alpha2+betaCO2 and alphaCO2beta+2 by hydrated electrons have been studied at different degrees of reduction. The results show that at pH 6.0 and 7.0 reduction of one heme group yields a species which reacts fast with carbon monoxide (rate constant of the order of 10(6) M-1S-1). At pH 6.0 the intermediates alphaCO2beta2 and alpha2betaCO2 bind carbon monoxide with a rate characteristic of the T state. At pH 7.0 alphaCO2beta2 is for the greater part in the T state, while in the case of alpha2betaCO2 the R and the T state are about equally populated.