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A system of calculating relative mobilities of mutant hemoglobins and globin chains in four methods of zone electrophoresis is described. In electrophoresis on cellulose acetate, TEB buffer, pH 8.5, mobilities are calculated as ratios of the mobility of simultaneously analyzed Hb C. In electrophoresis on citrate agar, pH 6.0, anodic mobilities are also related to Hb C, cathodic ones to Hb F. In globin electrophoresis in urea 2-mercaptoethanol buffers, pH 6.0 and 8.9, mobilities of the mutant globin chains are calculated in relation to the mobilities of normal alpha and beta chains. These calculations provide objective comparisons of mobilities of hemoglobins, including those analyzed at different times. The combined data permit recognition of many mutant hemoglobins.

The comparative mobilities, in citrate agar electrophoresis, of 91 mutant hemoglobins are presented in relation to their molecular structure and in some cases, to their mobilities in other types of electrophoresis. More than a third of the alpha chain mutants (11 of the 27 examined) and half of the beta chain mutants (29 of 55) differ to some extent from Hb A. The helical location of the substituted residue is an important determinant of hemoglobin mobility, which is also affected by a complex interplay of other factors. When the data are combined with those of several other types of electrophoresis, they often provide presumptive (or in some cases highly specific) identifications of mutant hemoglobins and hemoglobinopathies.

The amino acid substitution in a new hemoglobin variant, Hb Baylor (alpha2beta281 (EF5) Leu replaced by Arg), has been determined by application of column chromatography and amino acid analysis of the tryptic peptides. The hemoglobin is somewhat unstable and it has a high oxygen affinity. The propositus shows the opposing hematologic effects of these two properties--the instability being associated with increased destruction, and the high O2 affinity with increased production, of erythrocytes.

The genetic combination of Hb Mobile (beta 73 Asp replaced by Val) and Hb S (beta 6 Glu replaced by Val) was found in a healthy black man whose hemolysate resembles that of Hb S electrophoretically. His mother and sister have Hb AS; the father and brother have Hb A Mobile. No clinical nor hematologic abnormalities were detected in any member of the family. A slightly decreased oxygen affinity associated with Hb Mobile appears to have no clinical significance. Simple methods of differentiating Hb Mobile S from the electrophoretically similar but clinically severe Hb SD Los Angeles are described.

Hb Gun Hill has been found in an asymptomatic black female living in Alabama; neither her parents nor her two siblings carry the variant. The deletion of five amino acid residues in the beta chain of Hb Gun Hill (alpha2beta2 91-95 deleted) causes this variant to have a high oxygen affinity, an interaction coefficient of unity and an absence of the Bohr effect. The rate of oxidation of liganded Hb Gun Hill by the ferricyanide ion follows first-order kinetics. Hb Gun Hill is to a great extent dissociated into dimers over a wide range of pH values.