THERMODYNAMIC STUDIES OF THE REACTION OF 𝜷�93 SULPHYDRYL GROUP OF HUMAN HEMOGLOBIN WITH METHYL METHANETHIOSULPHONATE

Abstract

In order to determine the nature of the charged groups affecting sulphydryl reactivity, the reaction of hemoglobin with another sulphydryl reagent, was studied by potentiometric difference titration as a function of pH at 20oC and ionic strength 0.05 M. Differences were observed for various derivatives for the parameter H+ the number of protons released per sulphydryl group reacted. These differences reflect differences in tertiary structure between the derivatives studied rather than differences in quaternary structure. As a general conclusion, the reactivity of the cys F9 (93) β sulphydryl depends on two factors namely: the conformation of the sulphydryl group and the electrostatic effects of the charged ionizable groups on the protein.