Crystallography and mutagenesis of transketolase: mechanistic implications for enzymatic thiamin catalysis.

The ThDP dependent enzyme transketolase is a convenient model system to study enzymatic thiamin catalysis. Crystallographic studies of the enzyme have identified the ThDP binding fold, the V-conformation of ThDP as the relevant conformation in enzymatic catalysis and details of enzyme-substrate interactions. Based on this structural information, the function of various active site residues in substrate binding and catalysis has been probed by site-directed mutagenesis.