Characterization of a series of electrophoretic and enzyme activity variants of human glucose-phosphate isomerase.

A total of 3438 cord blood samples were screened for variants of erythrocyte glucose-phosphate isomerase. The five different electrophoretic, three activity/deficiency, and one thermostability variants distributed among 27 unrelated Caucasian families of that population, plus two electrophoretic variants previously described from three Amerindian tribes were subsequently examined for cryptic variation using activity and thermostability criteria. Although thermostability differences were observed between electrophoretic variants, no microheterogeneity within any one class of variant was detected.