Kinetics of the reconstitution of hemoglobin from semihemoglobins ? and ? with heme

Publisher Website
Google Scholar
Abstract
Kinetics of the reconstitution of hemoglobin from semihemoglobins α and β with hemin dicyanide have been investigated using three kinds of stopped-flow technique (Soret absorption, fluorescence quenching of tryptophan, and Soret CD). The semihemoglobins α and β are occupied by heme in the α and β chains, respectively, the other chain being heme-free. Based on the kinetic results, the following scheme for the reconstitution is proposed; First, hemin dicyanide enters the pocket-like site of the apo chains. Second, in semihemoglobin α, the CN-ligand in the fifth coordination position of iron is replaced by the imidazole ring of the proximal His immediately after the heme insertion. In contrast, semihemoglobin β changes its conformation after the heme insertion, and this is followed by the ligand replacement. Finally, the partial structure changes induced by the ligand replacement propagate onto the whole molecule and the final conformation is attained. The results indicate that semihemoglobin α retains a more rigid and organized structure, and more closely approaches its final structure than does semihemoglobin β.

This publication has 0 references indexed in Scilit: