Technical Report No. 12-85
Characterization of three electrophoretic variants of human erythrocyte triosephosphate isomerase found in Japanese
Asakawa J, Satoh CEditor’s note: A publication based on this report was published in Biochem Genet 24:131-48, 1986.
Summary
Three new electrophoretic variants of human erythrocyte triosephosphate isomerase (TPI) have been partially purified and compared with the normal isozyme with respect to stability, kinetics, and immunologic properties. TPI 2HR1 is an anodally migrating variant associated with markedly decreased enzyme activity. The level of enzyme activity in erythrocytes from the proband with phenotype TPI 1-2HR1 was about 60% of the normal mean. The variant allozyme was less stable than normal in guanidine denaturation tests, although it exhibited normal kinetic properties. TPI 2NG1, an anodally migrating allozyme associated with normal activity, was very thermolabile at 55 degrees centigrade and 57 degrees centigrade. It was also much more labile than normal in stability tests in buffers at pH 5 and pH 10, although it exhibited normal kinetic and immunologic properties. TPI 4NG1, a cathodally migrating variant associated with normal activity and normal kinetic as well as immunologic properties, was more stable than normal in pH 5 buffer. Family studies demonstrated that the unique characteristics of these variants are genetically transmitted. In two-dimensional electrophoresis of purified isozymes there is no difference between the variants and normal in the molecular weight axis, suggesting the variants result from single amino acid substitutions.
Three new electrophoretic variants of human erythrocyte triosephosphate isomerase (TPI) have been partially purified and compared with the normal isozyme with respect to stability, kinetics, and immunologic properties. TPI 2HR1 is an anodally migrating variant associated with markedly decreased enzyme activity. The level of enzyme activity in erythrocytes from the proband with phenotype TPI 1-2HR1 was about 60% of the normal mean. The variant allozyme was less stable than normal in guanidine denaturation tests, although it exhibited normal kinetic properties. TPI 2NG1, an anodally migrating allozyme associated with normal activity, was very thermolabile at 55 degrees centigrade and 57 degrees centigrade. It was also much more labile than normal in stability tests in buffers at pH 5 and pH 10, although it exhibited normal kinetic and immunologic properties. TPI 4NG1, a cathodally migrating variant associated with normal activity and normal kinetic as well as immunologic properties, was more stable than normal in pH 5 buffer. Family studies demonstrated that the unique characteristics of these variants are genetically transmitted. In two-dimensional electrophoresis of purified isozymes there is no difference between the variants and normal in the molecular weight axis, suggesting the variants result from single amino acid substitutions.