Cross-linking reaction of a valency asymmetrical hybrid hemoglobin formed in a mixture of hemoglobin A and methemoglobin.

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Abstract
It is known that hemoglobin A [Hb A (.alpha.2.beta.2)] is cross-linked by reaction with double-headed aspirin [bis(3,5-dibromosalicyl)fumarate] and the cross-linking site is the .beta.-cleft of the tetramer, the binding site of 2,3-diphosphoglycerate. Reaction of methemoglobin [MetHb(.alpha.2+.beta.2+)] with the reagent resulted in the formation of MetHbFu, which was confirmed to be a MetHb tetramer intramolecularly cross-linked at the same site. Unstable valency asymmetrical hybrid hemoglobin [Hb AM (.alpha..alpha.+.beta..beta.+)], which is assumed to be present in a mixture of Hb A and MetHb, could be fixed as a stable tetramer [HbAMFu] by the cross -linking reaction. The intramolecular cross-links in HbAMFu were at the same .beta.-cleft. It is suggested that MetHb forms the valency asymmetrical hybrid in the presence of Hb A.