Hemoglobin Cowtown (β146 HC3 His-Leu): A Mutant with High Oxygen Affinity and Erythrocytosis

A new mutant, hemoglobin Cowtown, has been found in a white man and his father, both of whom have erythrocytosis. The father had previously been treated with 32P for polycythemia vera. The abnormal hemoglobin is not detectable on electrophoresis in alkaline buffers, but it resolves distinctively on electrophoresis in citrate agar, pH 6.0; similarly, the abnormal beta-globin chain does not separate from beta-A in urea 2-mercaptoethanol buffers of pH 8.9, but it moves anodically to beta-A at pH 6.0. Peptide chromatography and amino acid analysis of the beta chain reveal that the C-terminal histidine residue (beta 146) has been replaced by leucine. Like several other hemoglobins substituted at this residue, Hb Cowtown has a high oxygen affinity and a diminished Bohr effect.