The effect of 4-isothiocyanatobenzoic acid on the oxygen-linked chloride binding sites in human hemoglobin: Influence on the alkaline Bohr effect

doi:10.1016/0006-291X(82)91258-X

Biochemical and Biophysical Research Communications

Volume 106, Issue 4, 30 June 1982, Pages 1325-1330

https://doi.org/10.1016/0006-291X(82)91258-X Get rights and content

Abstract

Human oxyhemoglobin reacted with 4-isothiocyanatobenzoic acid shows a decreased oxygen affinity that does not change with increasing chloride concentration indicating that all of the oxygen-linked chloride binding sites are blocked in the modified protein. By contrast, reaction of oxyhemoglobin with 4-isothiocyanatobenzenesulfonamide produces a modified protein with increased oxygen affinity below pH 7.3 that shows the expected decrease in oxygen affinity with increasing chloride concentration. The latter result demonstrates the importance of the negatively charged moiety in producing both the decrease in oxygen affinity and the effect on the oxygen-linked chloride binding sites produced by 4-isothiocyanatobenzoic acid. Reduction in the alkaline Bohr effect by 50% in the protein modified by 4-isothiocyanatobenzoic acid indicates that contribution to the alkaline Bohr effect is evenly divided between chloride dependent and chloride independent groups.

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The effect of 4-isothiocyanatobenzoic acid on the oxygen-linked chloride binding sites in human hemoglobin: Influence on the alkaline Bohr effect

Abstract

J. Biol. Chem

J. Biol. Chem

Biochem. Biophys. Res. Comm

J. Biol. Chem

J. Mol. Biol