An Active Acetaldehyde-Thiamine Intermediate

Acetolactate and Acetoin Synthesis in Ripening Peas

“…Some indication of the reasons for the diversity of products observed in the above systems may be obtained from the results of recent work on the nature of the a-carboxylase reaction (2,3,8,9). The decarboxylation of pyruvate by cell-free extracts of yeast involves the formation of first a-lactyl-2-thiamine pyrophosphate (activated pyruvate) from which a-hydroxyethyl-2-thiamine pyrophosphate (activated acetaldehyde) is derived by decarboxylation (4).…”

Reactions of Electron‐Rich Olefins with Proton‐Active Compounds

“…Aliphatic, aromatic, and heterocyclic amines react with the electron-rich olefins (4a) and ( 4 c ) with initial formation of extremely readily hydrolyzed "NH insertion products" (59), which can be isolated in the case of the secondary amines, but isomerize to the aminoamidines (60) in the cases of primary amines and hydrazine~"~! The reaction rate increases in the order aliphatic < araliphatic < aromatic amines.…”

Thiamin Pyrophosphate: Catalytic Mechanism, Role in Protein Turnover

“…Further characterization of the labeled material was done by using the "sulfite-cleavage" after Williams et al [10] and by treatment of "active acetaldehyde" with HJ, followed by alkaline hydrolysis which resulted in formation of 14C-labeled propionic acid. Additional evidence for the correctness of Breslow's proposal of the structure of active acetaldehyde came from experiments of Krampitz et al [11,12]. These authors had synthesized 2-(a-hydroxyethyl)-thiamin and could show that this synthetic material after incubation with ATP and pyrophosphorylating extracts from yeast was able to act as coenzyme of decarboxylation of pyruvate and of the formation of acetoin from acetaldehyde.…”