Functional properties of hemoglobin pôrto alegre ( α2Aβ29 Ser→Cys) and the reactivity of its extra cysteinyl residue

Abstract

Hemoglobin Pôrto Alegre ( α 2 A β 2 9 Ser→ Cys ) is an abnormal human hemoglobin that polymerizes by formation of intermolecular disulfide bonds between the extra cysteinyl residues at the β9 position. Functional studies of this hemoglobin indicate that its oxygen binding properties are unaffected by the polymerization. Both the tetramer and the disulfide polymers have oxygen affinities somewhat higher than normal hemoglobin and show slightly reduced heme-heme interaction. The Bohr effect is normal. In contrast to the behaviour of the β93-SH group, the reactivity of the extra -SH at β9 is only slightly altered by oxygenation of the hemoglobin.