Kim D H, Tucker-Kellogg G W, Lees W J, Walsh C T
Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, USA.
Biochemistry. 1996 Apr 30;35(17):5435-40. doi: 10.1021/bi952978s.
The stereochemistry of transient methyl group formation at C-3 of phosphoenolpyruvate (PEP) in the reaction catalyzed by 5-enolpyruvylshikimate 3-phosphate (EPSP) synthase has been examined using the pseudosubstrates, (E)- and (Z)-3-fluorophosphoenolpyruvate (FPEP). Kinetically stable, chiral [1H, 2H]fluoromethyl analogs of the reaction tetrahedral intermediate were isolated and subjected to decomposition and stereochemical analysis. EPSP synthase was found to catalyze the 2-re face addition of solvent-derived hydrogen to C-3 of FPEP (corresponding to the 2-si face of PEP). Comparison of these data with prior analogous work on the MurA reaction [Kim, D.H., Lees, W.J., & Walsh, C. T. (1995) J. Am. Chem. Soc. 117, 6380-6381] suggests that the two enolpyruvyl transferases share a common stereochemical course, further strengthening the mechanistic, structural, and evolutionary relationship between the two enzymes.
