Unequivalence between Hemoglobin Subunits

Abstract

The effects of inositol hexakisphosphate on the visible absorption spectrum of liganded valency hybrids .**GRAPHIC**. and .**GRAPHIC**. (where .alpha.CO, .alpha.+H2O, .alpha.+CN, and .beta.CO, .beta.+H2O, .beta.+CN represent the .alpha. and .beta. chain of Hb [human], respectively, in their CO aquomet and cyanomet forms) were examined in an attempt to determine if their .alpha. and .beta. chains were equally sensitive to the action of the anion. The difference spectra induced by inositol hexakisphosphate was different for the 2 chains. The .beta.+H2O subunit contributed chiefly to the absorbance changes, rather than .alpha.+H2O. In contrast, it was the .alpha.CO chain which was more sensitive to inositol hexakisphosphate than .beta.CO. The question of whether such a selective response would also occur in aquomethemoglobin and carboxyhemoglobin was discussed. Criteria of changes in the quaternary structure of hybrids was studied by measuring the effects of inositol hexakisphosphate on their UV absorption spectrum.