Structure and Mechanism of Action of the Active Center of Yeast Pyruvate Decarboxylase

Abstract Kinetic studies have shown that the two low molecular‐weight components of yeast pyruvate decarboxylase (thiamine pyrophosphate and Mg2⊕ ions) first add rapidly and reversibly to the apoenzyme in binary equilibria. The resulting adduct then “cyclizes” in a rate‐determining, practically irreversible reaction to form the thermodynamically stable holoenzyme. These results were supplemented and extended by the testing of numerous analogues of thiamine pyrophosphate in enzyme experiments and then used for the interpretation of the enzyme reaction.