A preparative method for the isolation of genetic variant forms of glucosephosphate isomerase and a study of five variants.

A method has been developed for the rapid, quantitative separation of normal and abnormal glucosephosphate isomerase allozymes from individuals heterozygous for genetic variant forms of the enzyme. The method utilizes a substrate gradient elution of the enzyme from carboxymethyl Biogel and is far superior in terms of resolution and recovery to methods based on electrophoresis and isoelectric focusing. Five different genetic variant forms of the enzyme were isolated and subjected to a systematic comparison of their physical, catalytic and stability properties. While the physical and catalytic properties of most of the variants were similar, clear differences in the stability of the allozymes were apparent. In order to detect mutations affecting the stability, a series of different stability tests are required.