The effect of temperature on the reaction of carbon monoxide with oxygenated haemoglobin.

Abstract

SUMMARY1. The rate at which carbon monoxide displaces oxygen from its combination with haemoglobin in solution, has been measured spectrophotometrically, using a rapid-mixing stopped-flow technique.2. In the presence of carbon dioxide, the reaction proceeds by a unimolecular dissociation, with a rate constant r.3. The relationship of the reciprocal of r to the ratio Po2IPco is non-linear, and a different curve is obtained at each carbon monoxide concentration.4. From measurements of the rate constant at temperatures between 5 and 350 C, it is concluded that the non-linearity is due to the formation at a finite rate of an intermediate complex, CO2Hb4O6, by the reaction of carbon dioxide with Hb4O6.

The Bohr effect on the reaction of carbon monoxide with fully oxygenated haemoglobin.

“…The rate constant, r, of the logarithmic decay was determined by the method of least squares, using a computer. Further experimental details may be found in earlier published work (Sirs, 1974(Sirs, , 1976.…”

“…Under physicochemical conditions, in buffer solutions, Roughton (1934) and Gibson & Roughton (1955) established that the reciprocal of the rate constant of the reaction, 1/r, varied in a linear manner with the ratio of the O2 to CO concentrations. Later work by Sirs (1974Sirs ( , 1976 indicated that the reaction no longer behaved in this manner when the solutions were equilibrated with CO2. These Allen & Root. From an analysis of these results a reaction mechanism of the Bohr effect is proposed.…”