The electrochemical investigation of the catalytic power of pyruvate decarboxylase and its coenzyme

The change in the energy barriers for the heterogeneous reduction of pyruvate decarboxylase (PDC) relative to its coenzyme, thiamin pyrophosphate (ThPP), was determined experimentally using square wave voltammetry (SWV) to be 5.3 kcal/mol. These results are in agreement with those of reaction rate acceleration provided by thiamin-dependent decarboxylases relative to their coenzyme as determined kinetically based on the pK(a) suppression by the enzyme environment.