title: Crystalline enzyme.substrate complexes of asparate aminotransferase.
abstract: Crystalline complexes of cytoplasmic aspartate aminotransferase of pig heart with the substrates L-glutamate and L-aspartate, and with other amino acids, have been prepared and polarized light absorption spectra have been measured. Striking differences in the directions of polarization of the absorption bands are seen. A complete half-transamination of pyridoxal phosphate to pyridoxamine phosphate by aspartate or by cysteine sulfinate can be demonstrated in the crystal as can the accumulation of a quinonoid intermediate with erythro-beta-hydroxyaspartate. X-ray diffraction studies show that the crystals with erythro-beta-hydroxyaspartate and alpha-methylaspartate are isomorphous with those of both alpha and beta subforms of the native enzyme.
mesh_terms: D000596:Amino Acids; D000818:Animals; D001219:Aspartate Aminotransferases; D001224:Aspartic Acid; D001665:Binding Sites; D003460:Crystallization; D009206:Myocardium / Q000201:enzymology; D011485:Protein Binding; D013053:Spectrophotometry; D013379:Substrate Specificity; D013552:Swine; D014961:X-Ray Diffraction
chemical_list: D000596:Amino Acids; D001224:Aspartic Acid; D001219:Aspartate Aminotransferases