Inhibition of mandelate racemase by the substrate-intermediate-product analogue 1,1-diphenyl-1-hydroxymethylphosphonate.

Mandelate racemase has been studied as a paradigm for enzyme-catalyzed abstraction of a proton from carbon acids with relatively high pKa values. 1,1-Diphenyl-1-hydroxymethylphosphonate is a substrate-intermediate-product analogue and is a modest competitive inhibitor of the enzyme (Ki=1.41+/-0.09 mM), suggesting that simultaneous binding of the two phenyl groups obviates mimicry of the aci-carboxylate function of the intermediate by the phosphonate group.