Oxaloacetate decarboxylase-pyruvate

Kosicki, G. W., Westheimer, F. H. Oxaloacetate decarboxylase from cod. Mechanism of action and stereoselective reduction of pyruvate by borohydride. Biochemistry 7, 4303—4309 (1968). 

OVERSATURATION OXALOACETATE DECARBOXYLASE Oxaloacetate, synthesis in gluconeogenesis, PYRUVATE CARBOXYLASE PHOSPHOENOLPYRUVATE CARBOXYKI-NASE (PYROPHOSPHATE)... 

Oxaloacetate is also decarboxylated without phosphorylation of the enolate anion formed but with release of free pyruvate. Both pyruvate kinase and PEPCK can act as oxaloacetate decarboxylases.261... 

Other types of enzymes When no oxidase or dehydrogenase is available for a target analyte, other types of enzymes have been used for biospedfic recognition e.g. for citric acid detection, citrate lyase, and amperometric detection was possible by coupling to two more enzymatic reactions oxaloacetate decarboxylase and pyruvate oxidase, which convert citric add into H2O2 with the latter being monitored amperometrically with an H202 probe. For detection of acetic add, acetate kinase is used, coupled to pyruvate kinase and pyruvate oxidase [34,35]. 

Prodromidis et al. [35] Citric acid Fruits, juices and sport drinks Citrate lyase (in solution), oxaloacetate decarboxylase and pyruvate oxidase/ sandwiched between a cellulose acetate membrane and a protective polycarbonate membrane H202 probe (Pt electrode) ... 

The successive determination of both transaminases has also been carried out with a sequence electrode containing oxaloacetate decarboxylase and pyruvate oxidase (Kihara et al., 1984b). The enzymes were coadsorbed on a PVC membrane of 40 pm thickness in the presence of thiamine pyrophosphate, FAD, and MgC. ... 

It may be observed that, for the cycle to revolve, a supply of oxaloacetic acid is required with which the acetyl-CoA can react. Of course, oxaloacetic acid is being constantly re-formed as each revolution of the cycle is completed, but, nonetheless, it is not surprising to find that many cells, especially in bacteria, take precautions against running out of so essential a primer by having an alternative source of oxaloacetic acid. The alternative source is provided by an enzyme, oxaloacetic decarboxylase which catalyses the direct fixing of carbon dioxide on to pyruvic acid to form oxaloacetic acid as in equation (24) ... 

The mechanism of the enzymic decarboxylation of oxaloacetate presumably resembles that of the metal ion-catalyzed reaction (Scheme III), in which the enzyme-bound metal chelates to the a-carboxyl and the keto carbonyl of the substrate prior to decarboxylation (cf. Scheme II). Interestingly, an enzyme identified as oxaloacetate decarboxylase was later identified as pyruvate kinase... 

The enzymes described above that convert oxaloacetate to pyruvate and CO2 appear to use metal chelation to stabilize the enolate formed by decarboxylation. Many other /3-ketoacid decarboxylases use a similar mechanism. However, there are a few decarboxylations of /3-keto acids or their functional equivalents in which no metal ion is involved. One is the case of acetoacetate decarboxylase, which functions by means of a Schiif base mechanism. A few additional examples are described below. All these cases involve particularly stable enolates. 

Fig. 1. The diversity of anaplerotic enzymes present in Corynebacterium glutamicum. Numbers next to enzyme names represent typical in vitro activities in mU mg protein". Abbreviations PEPCk, phosphoenoipyruvate carboxykinase OAADc, oxaloacetate decarboxylase PyrCx, pyruvate carboxylase PEPCx, phosphoe o/pyruvate carboxylase...

Figure 13.4 Diacetyl production from citrate. CL, citrate lyase OD, oxaloacetate decarboxylase LDH, lactate dehydrogenase AS, a-acetolactate synthase PDHC, pyruvate dehydrogenase complex.

Oxaloacetate decarboxylase odx Decarboxylate oxtiloacetate to form pyruvate... 

Anaplerotic reactions refer to C3-carboxylation and C4-decarboxylation around the phosphoenolpyruvate-pyruvate-oxaloacetate node, which interconnect the TCA cycle with glycolysis. These reactions result in direct oxaloacetate formation or depletion. Carboxylation of phosphoenolpyruvate catalyzed by phosphoenolpyruvate carboxylase and that of pyruvate by pyruvate carboxylase contribute to its formation. Accordingly, decarboxylation of oxaloacetate catalyzed by phosphoenolpyruvate carboxykinase and oxaloacetate decarboxylase form phosphoenolpyruvate and... 

Biotin (referred to as vitamin H in humans) is an essential cofactor for a number of enzymes that have diverse metabolic functions. Almost a dozen different enzymes use biotin. Among the most well-known are acetyl-CoA carboxylase, pyruvate carboxylase, propionyl-CoA carboxylase, urea carboxylase, methylmalonyl-CoA decarboxylase, and oxaloacetate decarboxylase. Biotin serves as a covalent bound CO2 carrier for reactions in which CO 2 is fixed into an acceptor by carboxylases. Then this carboxyl group in an independent reaction can be transferred from the acceptor substrate to a new acceptor substrate by transcarboxylases, or the carboxyl group can be removed as CO 2 by decarboxylases. 

The key enzymes related to SA production pathways include PEP carboxykinase (PEPCK), oxaloacetate decarboxylase, and pyruvate kinase. PEPCK from A. suc-ciniciproducens, a C02-fbcing enzyme that catalyze the ATP-dependent reversible decarboxylation of oxaloacetate to yield PEP, is well characterized, and was het-erologously overexpressed in E. coli for the enhanced production of SA [27, 28]. 

Iversen T-G, Standal R, Pederson T, Caucheron DH (1994) IS 1032 from Acetobacter xylinunty a new mobile insertion sequence. Plasmid 32 46-54 Jabalquinto AM, Laivenieks M, Zeikus JG, Cardemil E (1999) Characterization of the oxaloacetate decarboxylase and pyruvate kinase-like activities of Saccha-romyces cerevisiae and Anaerobiospirillum succiniciproducens phospho-enolpyruvate carboxykinases. J Prot Chem 18 659-664 Jarvis L (2001) Lactic acid outlook up as polylactide nears market Chem Mark Repor 259(9) 5,14... 

This enzyme catalyses the decarboxylation of the ) -ketoacid oxaloacetate, with the same stoichiometry as acetoacetate decarboxylase. The former however, requires a Mn ion for activity and is insensitive to the action of sodium borohydride. This duality of mechanism is not unlike the one observed for enzymatic aldol condensation, where enzymes of Class 1 react by forming Schiff-base intermediates, whereas enzymes of Class II show metal ion requirements [47]. Oxaloacetate decarboxylase from cod also catalyses the reduction by borohydride of the enzymatic reaction product pyruvate. This is evidenced by the accumulation of D-lactate in presence of enzyme, reducing agent, and manganous ions. It has been proposed that both reduction and decarboxylation occur by way of an enzyme-metal ion-substrate complex in which the metal ion acts as an electron sink, thereby stabilizing the enolate ion formed in the decarboxylation reaction [48] ... 

Figure 1.2. Citrate metabolism in Lactococcus, Leuconostoc, and Weissella species. Key for the enzymes CL, citrate lyase OAD, oxaloacetate decarboxylase LDH, lactate dehydrogenase PDC, pyruvate decarboxylase ALS, a-acetolactate synthase ADC, a-acetolactate decarboxylase DAR, diacetyl acetoln reductase BDH, 2,3-butanediol dehydrogenase Tppi, thiamine pyrophosphate.

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