title: The first stable variant of erythrocyte glucose-phosphate isomerase associated with severe hemolytic anemia.
abstract: A new variant of glucosephosphate isomerase (GPI) associated with hemolytic anemia, mental retardation, and muscular hypotonia is described. The defective enzyme showed increased affinity for fructose-6-phosphate (F-6-P), decreased affinity for glucose-6-phosphate (G-6-P) altered electrophoretic and isoelectrofocusing patterns, and shift to the left of the precipitin curve. The enzyme was stable under all the conditions tested (heat, urea, guanidine-HCl, and storage). Optimum pH, Ki for 6-phosphogluconic acid (6-PGA) and for erythrose-4-phosphate (E-4-P), molecular weight, GPI-related antigen concentration, immunodiffusion pattern, and immunoinactivation were in the normal range. This is the first example of the association of a stable mutant GPI with severe hemolytic anemia. Enzyme instability has been present in all previously reported cases.
mesh_terms: D000745:Anemia, Hemolytic, Congenital / Q000150:complications / Q000201:enzymology*; D002675:Child, Preschool; D004591:Electrophoresis, Polyacrylamide Gel; D004912:Erythrocytes / Q000201:enzymology*; D005260:Female; D014644:Genetic Variation; D005956:Glucose-6-Phosphate Isomerase / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D006801:Humans; D008607:Intellectual Disability / Q000150:complications; D007525:Isoelectric Focusing; D008565:Membrane Proteins / Q000097:blood; D009123:Muscle Hypotonia / Q000150:complications; D009154:Mutation; D011233:Precipitin Tests
chemical_list: D008565:Membrane Proteins; D005956:Glucose-6-Phosphate Isomerase