XAS investigation of the nickel active site structure in Escherichia coli glyoxalase I

Escherichia coil glyoxalase I (GU) is the first example of an isomerase tha t is maximally activated by Ni2+. In contrast with GlxI enzymes from other sources that are Zn enzymes, E. coli GlxI is not active with Zn bound. Stru ctural details from X-ray absorption spectroscopic analyses are reported fo r the active site Ni center and the Zn-substituted enzyme. The available da ta regarding the structure of the active Ni site are consistent with a six- coordinate Ni(Glu)(2)(His)(2)(OH2)(2) site in the enzyme.