Carbon monoxide binding to a fish hemoglobin under photostationary conditions

Determinations of carbon monoxide binding curves for hemoglobin from Brevoortia tyrannus under equilibrium and photostationary conditions show that in the light, the curve is shifted to the right and altered in shape. The Bohr effect is much less in the light. The kinetics of the transition between equilibrium and photostationary states has been examined. All of the results are satisfactorily described using the two-state model of Monod, J. Wyman, J., and Changeux, J.P. (1965) J. Mol. Biol. 12, 88-118 with the assumption that light produces an additive increase in the rate of dissociation of ligand from the R and T states.