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

Production of Aldehydes by Biocatalysis

“…Although very rare, some bacterial PDCs have been described and even produced recombinantly [49,52,53]. Generation of an acetaldehyde is an essential step in the fermentative production of ethanol, followed by the conversion of acetaldehyde to ethanol mediated by alcohol dehydrogenases [48,50,54,55]. This step is considered to be the primary elimination step for pyruvate in the production of lactic acid by Rhyzopus oryzae [48], while both lactate dehydrogenases and PDC share the same substrate.…”

“…This process is Mg 2+ dependent and requires the metabolically active coenzyme thiamine pyrophosphate (ThPP). Interestingly, ThPP catalyzes this reaction alone but with lower efficiency [ 50 , 51 ]. This enzyme is frequently found in fungi, yeast and plants; however, it is absent in animals and seldom present in prokaryotes [ 48 ].…”

A potential energy profile of the catalytic cycle of pyruvate decarboxylase

“…For comparison, the rate of the ThDP-catalyzed reaction is 10 6 times slower with respect to the process catalyzed by the full enzyme [2]. The difference in activation free energies between the reaction catalyzed by ThDP only and the corresponding enzymatic process was estimated to be 5 -6 kcal•mol -1 , based on square-wave voltammetry measurements [7]. In ThDP a thiazolium ring and a pyrimidine ring are connected by a methylene bridge (Scheme 2), and interactions with the amino acids at the active site determine its "V" conformation [8], with the two heterocycles eclipsed [9].…”

“…Complex of product acetaldehyde with the ylide/ carbene thiamin in the 4'-amino tautomeric form(7). Energies are calculated at the B3LYP 6-31G (d, p) level of theory.…”