Wheat germ decarboxylase

Fluoropyruvate is converted quantitatively by pyruvate decarboxylase from wheat germ into acetate, fluoride (F ), and carbon dioxide. Propose a reaction mechanism. See Gish, G., Smyth, T., and Kluger, R. (1988) /. Am. Chem. Soc. 110, 6230-6234. 

For all pyruvate decarboxylases the tetramer is the active species (Table 3a and b). Higher active association states have been described for PDC from maize [127], pea [125], and wheat germ [124], For PDCZ.m., small amounts of active octamers have been detected, depending on the protein concentration... 

Meso-a, e-diaminopimelate decarboxylase Bacillus sphaericus, wheat germ DL-Diaminopimelate Inversion 259, 260... 

The stereochemistry of meso-a,e-diaminopimelate decarboxylase from a eukaryotic source (wheat germ) also involves inversion of configuration (260). As suggested by Floss and Vederas inversion might be comprehensible if the enzyme evolved from a preexisting L-amino acid decarboxylase in which the dispositions... 

Kluger R, Gish G, Kaufman G (1984) Interaction of thiamin diphosphate and thiamin thiazolone diphosphate with wheat germ pyruvate decarboxylase. J Biol Chem 259 8960-8965... 

Crout DHG, Littlechild J, Morrey SM. Acetoin metaboUsm stereochemistry of the acetoin produced by the pyruvate decarboxylase of wheat germ and by the a-acetolactate decarboxylase of Klebsiella aerogenes. J. Chem. Soc., Per-kinTrans. 1 1986 105-108. 

In 1961 Jimi proposed the two-site theory of the mechanism of acyloin formation by pyruvate decarboxylase [15]. This theory was later confirmed by others [18,28]. According to the model, at the first site pyruvate is decarboxylated to an aldehyde-diphosphatamine complex (HETPP) called active acetaldehyde. The active acetaldehyde moiety is then irreversibly transferred to the second site, where reversible dissociation to free aldehyde takes place. The model is based on the observation that pyruvate decarboxylase not only forms free acetaldehyde as the major end-product of decarboxylation of an a-keto acid but also catalyzes formation of C-C bonds via an acyloin reaction in which free aldehyde competes with a proton for bond formation with the a carbanion of EDETPP. Thus the addition of a C2 unit equivalent to acetaldehyde by means of HETPP to a carbonyl group results in an (i )-hydroxy ketone [29]. For instance, the production of acetoin (methylacetyl carbinol) results when acetaldehyde is allowed to accumulate or is added to the reaction mixture [28]. This phenomenon was confirmed using pyruvate decarboxylase from different sources (wheat germ, yeast, and bacteria) [15,28,30]. 

Pyruvate decarboxylase (PDase, EC 4.1.1.1), which catalyzes the reaction as shown in Eq. (17), has been studied since the early twentieth century as one of the key enzymes working in glycolysis [31-33]. It has l n isolated from yeast [34], wheat germ [35], sweet potato [36], and a wide variety of other sources. Recently, this enzyme was revealed to also play an important role in nonmevalonate pathway for terpenoid biosynthesis [37]. 

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