[Hemoglobin M Saskatoon alpha 2 beta 2 63 (E7) His--Tyr. Structural identification, hemichrome formation and...

During examination of the patient with methemoglobinemia of unclear ethiology abnormal Hb was found in the blood hemolysate. The primary structure determination allowed to identify the variant as Hb M Saskatoon with alpha 2 beta 2 63 (E7) His leads to Tyr substitution, that is the first known case of Hb M Saskatoon bearing in the Soviet Union. From the investigation of some physico-chemical properties it was concluded that not only the distal histidine can play the role of the sixth endogenous ligand at the hemichrome formation. The proteolytic degradation of met Hb M Saskatoon showed, that a shift of the distal residue (E7) to the heme ligand position does not itself lead to a considerable increase of the conformational lability of the protein as in the case of a few hemichrome forms.