Yeast pyruvate decarboxylase

The yeast pyruvate decarboxylase is rather specific with respect to the acyl moiety that is added to the aldehyde. Only a few 2-oxo acids can be used as acyl donors besides pyruvic-acid39. For example, treatment of benzaldehyde with 2-oxobutanoic acid and 2-oxopentanoic acid, respectively, and prewashed Saccharomyces cerevisiae gave the corresponding (/ )-acyloin derivatives in 15 25% yield with an enantiomeric excess >95%. 

Reddy et al. (1983) concluded that NO inactivation of iron-sulfur proteins was the probable mechanism of botulinal inhibition in nitrite-tteated foods. In support of this conclusion, Carpenter et al. (1987) observed decreased activity of clostridial pyruvate-ferredoxin oxidoteductase and lower cytochrome c reducing ability by ferredoxin in extracts of cells treated with nitrite. NO tteatment also inhibits yeast pyruvate decarboxylase (a non-iron-sulfur protein) and py-ruvate-ferredoxin oxidoteductase from C. perfringens (McMindes and Siedler, 1988). They suggested that thiamine-dependent decarboxylation of pyruvate may be an additional site for antimicrobial effects of NO. 

Discuss the mechanism of action of brewer s yeast pyruvate decarboxylase using orbital interaction theory wherever appropriate. For the mechanism, see Zeng, X. Chung, A. Haran, M. Jordan, F., J. Am. Chem. Soc., 1991, 113, 5842. 

Most known thiamin diphosphate-dependent reactions (Table 14-2) can be derived from the five halfreactions, a through e, shown in Fig. 14-3. Each halfreaction is an a cleavage which leads to a thiamin- bound enamine (center, Fig. 14-3) The decarboxylation of an a-oxo acid to an aldehyde is represented by step b followed by a in reverse. The most studied enzyme catalyzing a reaction of this type is yeast pyruvate decarboxylase, an enzyme essential to alcoholic fermentation (Fig. 10-3). There are two 250-kDa isoenzyme forms, one an a4 tetramer and one with an ( P)2 quaternary structure. The isolation of ohydroxyethylthiamin diphosphate from reaction mixtures of this enzyme with pyruvate52 provided important verification of the mechanisms of Eqs. 14-14,14-15. Other decarboxylases produce aldehydes in specialized metabolic pathways indolepyruvate decarboxylase126 in the biosynthesis of the plant hormone indoIe-3-acetate and ben-zoylformate decarboxylase in the mandelate pathway of bacterial metabolism (Chapter 25).1243/127... 

Baker s yeast pyruvate decarboxylase, 301-302 mechanism, 302 Basicities gas phase, 97... 

B.H. Robinson and K. Chun. 1993. The relationships bet veen transketolase, yeast pyruvate decarboxylase and pyruvate dehydrogenase of the pyruvate dehydrogenase complex FEBS Lett. 328 99-102. (PubMed)... 

Conformational analysis by ORD and CD of yeast pyruvate decarboxylase dependent on thiamine pyrophosphate showed large changes in the aromatic region (282, 288 nm) and in the absorption band of thiazolium ion (near 262 nm), indicating interactions between the thiamine pyrophosphate and tryptophan (361). 

Yeast pyruvate decarboxylase (wild type), pyruvamide activated > 600... 

Scheme 1 Mechanism of yeast pyruvate decarboxylase YPDC.

In 1970, there appeared two relevant publications modeling ThDP-catalyzed reactions in solvents of different dielectric solvent. Both Lienhard and coworkers and Kemp and O Brien presented model studies, which suggested that a solvent of low dielectric medium accelerated thiamin-catalyzed reactions. At the same time, Ullrich and Donner presented the first enzymatic evidence suggesting that the enzyme yeast pyruvate decarboxylase has a hydrophobic active center on the basis of studies with a fluorescent label. ... 

Removal of CO2 from pyruvate. This reaction is carried out by the pyruvate decarboxylase (El) component of the complex. Like yeast pyruvate decarboxylase, responsible for the production of acetaldehyde, the enzyme uses a thiamine pyrophosphate cofactor and oxidizes the carboxy group of pyruvate to CO2. Unlike the glycolytic enzyme, acetaldehyde is not released from the enzyme along with CO2. Instead, the acetaldehyde is kept in the enzyme active site, where it is transferred to Coenzyme A. 

Hohmann S, Cederberg H. (1990). Autoregulation may control the expression of yeast pyruvate decarboxylase structural genes PDCl and PDC5. Eur J Biochem, 188, 615-621. 

Schellenberger, A. Structure and mechanism of action of the active centre of yeast pyruvate decarboxylase. Angew. Chem. Int. Ed. Engl. 6, 1024-1035 (1967)... 

Figure 5.4 Structural formulae of thiamin phosphate esters. At present, five natural thiamin phosphate derivatives have been described thiamin monophosphate (ThMP) thiamin diphopshate (ThDP) thiamin triphosphate (ThTP) adenosine thiamin diphosphate (AThDP) and adenosine thiamin triphosphate (AThTP). Catalytic intermediates, such as for instance a-hydroxyethyl thiamine diphosphate formed by the action of yeast pyruvate decarboxylase (EC 4.1.1.1), are not considered here.

The determination of the dissociation or association constants for TPP is only possible when a reversible nature of binding of TPP to the apoenzyme can be demonstrated. In all cases where an irreversible binding of TPP to the apoenzyme is found, for instance in yeast pyruvate decarboxylase, the reconstitution process can only be studied kinetically. 

The reaction, carried out in solventless conditions and using Brewer s yeast pyruvate decarboxylase at 500 mM NaHC03-Na2C03 buffer and pH 11, gives a yield of 81 % in pyruvic acid [57]. 

Neuser F., Zorn H., Berger R.G. Generation of odorous acyloins by yeast pyruvate decarboxylases and their occurrence in sherry and soy sauce. Journal of Agricultural and Food Chemistry, 48 6191-6195... 

Stereoselective carbon-carbon bond-forming reactions are among the most useful S5mthetic methods in asymmetric synthesis as they allow the simultaneous creation of up to two adjacent stereocenters. Acyloin formation mediated by thiamine diphosphate-dependent decarboxylase, yeast pyruvate decarboxylase, bacterial benzoylformate decarboxylase, and phenylpyruvate decarboxylase has been reported [142-147]. 

Pyruvate decarboxylase (EC 4.1.1.1) has been characterized in different sources including yeast, bacteria, wheat, maize, sweet potato, and plants [8]. This is the first enzyme of the branch of the glycolytic pathway, which under anaerobic conditions leads to nonoxidative decarboxylation of pyruvate to reduced end-products [9]. In the case of yeast, pyruvate decarboxylase together with alcohol dehydrogenase (EC 1.1.1.1) converts pyruvate to ethanol. 

Kren and co-workers [19] studied acyloin condensation between active acetaldehyde generated from pyruvate and a range of aromatic aldehydes. The enzyme used was yeast pyruvate decarboxylase purified to homogeneity. All of the acyloins produced were of R configuration and possessed a very high optical purity. 

Though use of isolated purified enzymes is advantageous in that undesirable byproduct formation mediated by contaminating enzymes is avoided [37], in many industrial biotransformation processes for greater cost effectiveness the biocatalyst used is in the form of whole cells. For this reason baker s yeast, which is readily available, has attracted substantial attention from organic chemists as a catalyst for biotransformation processes. One of the first commercialized microbial biotransformation processes was baker s yeast-mediated production of (R)-phenylacetyl carbinol, where yeast pyruvate decarboxylase catalyzes acyloin formation during metabolism of sugars or pyruvate in the presence of benzaldehyde [38]. 

Using A. calcoaceticus, the productivity of the process (mg of acyloin product per g cell DW per hour) was much higher than the optimal productivity observed in the less enantiospecific reaction catalyzed by P. putida [90]. This productivity compares very favorably with yields of the acyloin product of yeast pyruvate decarboxylase where optimal product formation in 1-h incubation periods amounted to 0.2 g per g yeast DW [50]. 

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