Hemoglobin Brest [beta 127 (H5)Gln----Lys] a new unstable human hemoglobin variant located at the alpha 1 beta 1 interface with specific electrophoretic behavior.

Hb Brest [beta 127 (H5)Gln----Lys] is a new unstable variant located at the alpha 1 beta 1 interface at the same position as Hb Complutense [beta 127(H5)Gln----Glu]. In each of these, the substitution produces a distinct alteration in charge, yet both variants move with Hb A in conventional electrophoresis. This peculiar electrophoretical behavior may be due to the molecular position of the modified residue, which is deeply buried inside the tetramer.