Isoelectric-focusing of galactokinase in lens and other tissues

Thin-layer isoelectric focusing was used to investigate galactokinase in lenses from humans, cows, rats, rabbits and also in other tissues (red cells, liver, kidney, brain, placenta) from these species. In each case the enzyme activity was present as a single isozyme. The isoelectric point was the same in lens, red cell and other tissues of the same species, but differed from species to species. Post-translational modification due to deamidation was not detected in the lens or red cell from these species. Galactokinase activities in whole tissue extract were determined in different tissues of the various species. There were wide variations in activity. In the adult human lens, both normal and cataractous, it was low. The findings indicate that isoelectric focusing of RBC galactokinase combined with specific enzyme staining allows one to monitor lens galactokinase in patients with cataracts.