Analysis of human haptoglobin‐hemoglobin complexes by micro two‐dimensional electrophoresis

A microscale‐multisample two‐dimensional electrophoretic technique, in which no denaturing agent is used, was applied to the analysis of three phenotypes of haptoglobin and their hemoglobin complexes in human sera. Haptoglobin‐hemoglobin complexes did not dissociate during the electrophoretic run, so their pIs and apparent molecular weights could be estimated. The number of spots of haptoglobin‐hemoglobin complex derived from a haptoglobin molecular species coincided with the number of β chains involved in it. Heterogeneity in pI of the haptoglobin‐hemoglobin complexes was observed, which suggests the heterogeneous binding of an αβ half‐molecule of hemoglobin to a β chain of haptoglobin.