Catalytic metal ion binding in enolase: the crystal structure of an enolase-Mn2+ -phosphonoacetohydroxamate complex at 2.4-angstrom resolution

The glycolytic enzyme enolase requires two divalent metal ions per active site to catalyze the forming of phosphoenolpyruvate from 2-phospho-D-glycerate by dehydration. The position of site II of the second metal ion, having a lower affinity for Mg2+ ions, is determined and quarter complex structure between the Mn2+ ions and the transition-state analogue phosphonoacetohydroxamate enolase is analyzed. The sequential reaction mechanism explains the enolase inactivity caused by the increase in Mg2+ concentrations.