title: On the three-dimensional structure and catalytic mechanism of triose phosphate isomerase.
abstract: Triose phosphate isomerase is a dimeric enzyme of molecular mass 56 000 which catalyses the interconversion of dihydroxyacetone phosphate (DHAP) and D-glyceraldehyde-3-phosphate. The crystal structure of the enzyme from chicken muscle has been determined at a resolution of 2.5 A, and an independent determination of the structure of the yeast enzyme has just been completed at 3 A resolution. The conformation of the polypeptide chain is essentially identical in the two structures, and consists of an inner cylinder of eight strands of parallel beta-pleated sheet, with mostly helical segments connecting each strand. The active site is a pocket containing glutamic acid 165, which is believed to act as a base in the reaction. Crystallographic studies of the binding of DHAP to both the chicken and the yeast enzymes reveal a common mode of binding and suggest a mechanisms for catalysis involving polarization of the substrate carbonyl group.
mesh_terms: D000818:Animals; D001665:Binding Sites; D002238:Carbohydrate Epimerases / Q000378:metabolism*; D002384:Catalysis; D055598:Chemical Phenomena; D002621:Chemistry; D046911:Macromolecular Substances; D008958:Models, Molecular; D009132:Muscles / Q000201:enzymology*; D011487:Protein Conformation; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D014305:Triose-Phosphate Isomerase / Q000378:metabolism*; D014961:X-Ray Diffraction
chemical_list: D046911:Macromolecular Substances; D002238:Carbohydrate Epimerases; D014305:Triose-Phosphate Isomerase