Purification, crystallization and preliminary X-ray analysis of aspartokinase III from Escherichia coli.

Aspartokinase III catalyzes the commitment step in the aspartate metabolism pathway, the phosphorylation of aspartic acid. The Escherichia coli enzyme has been crystallized in the presence of its natural substrate (aspartic acid) and Mg-ADP and diffraction data has been collected at a synchroton source. The crystals belong to the orthorhombic space group C222(1), with unit-cell parameters a = 60.44, b = 190.31, c = 99.55 A, and data 99.3% complete to 2.7 A. Solving the structure of AK III will provide the first structure of an aspartokinase from any organism.