Abstract
The three-dimensional structure of a mutant of the aspartate aminotransferase from Escherichia coli , in which the active-site lysine has been substituted by alanine (K258A), has been determined at 2.8-angstrom resolution by X-ray diffraction. The mutant enzyme contains pyridoxamine phosphate as cofactor. The structure is compared to that of the mitochondrial aspartate aminotransferase.