Hemoglobin Mahidol: a new hemoglobin α-chain mutant

Abstract

A slow (less anionic) hemoglobin mutant has been detected by starch gel electrophoresis of hemoglobin from three unrelated patients in Bangkok. Dissociation of the abnormal hemoglobin with p-hydroxymercuribenzoate showed that the α-chain was the site of the mutation. The mutant α-chain was isolated by carboxymethylcellulose chromatography in 8 M urea and 0.05 M β-mercaptoethanol. Peptide maps of trypsin and cyanogen bromide cleaved α-chain indicated that the amino acid alteration of the mutant was in the peptide corresponding to residues 62–76 of the α-chain. Further cleavage of this peptide with 0.25 M acetic acid at 110 °C showed that residue 74 was changed from an aspartyl to a histidyl residue, a mutation not previously described. It is proposed that this new hemoglobin α274His β2A be called hemoglobin Mahidol after Mahidol University in Bangkok. In one of the three patients showing hemoglobin Mahidol, interaction with α-thalassemia occurs and, in this patient, hemoglobin A is totally absent, being replaced by hemoglobin Mahidol together with some hemoglobin H (β4A).