Kinetics of the reaction of the masked sulphydryl groups of haemoglobins A, E and New York with p-chloromercuribenzoate

Abstract

The order of reaction of the masked (α 104 and β 112) sulphydryl groups of human oxyhaemoglobin with p-chloromercuribenzoate was found to be 0.5 with respect to the haemoglobin component. The rate of reaction for haemoglobin E is approximately twice, and for haemoglobin New York slightly greater than, that for haemoglobin A at pH 7.0, 25 °C and 0.6 ionic strength. The effects of pH, ionic strength and temperature on the reaction rates for haemoglobins A and E were compared. It is concluded that the monomers of the haemoglobins are the only major reactive species, and the dimer-monomer dissociation constants are smaller for the normal haemoglobin than for the abnormal haemoglobins E and New York which have amino acid replacements in the contacts which form αβ dimers. © 1973.