Oxidation of pyruvic acid

Write a balanced equation for the oxidation of pyruvic acid to CC and H20. 

Summarizing the results obtained by controlled potential electrolysis and polarography, the reaction process for the electrolytic evolution of CO2 was estimated to be as follows the first step was one electron transfer from DMFC in NB to FMN in W as in Eq. (7). The second step was the catalytic reduction of O2 by FMNH as in Eq. (8). The final step was the oxidation of pyruvic acid by the reduction product of O2, H2O2, in W as in Eq. (9), well-known as an oxidative decarboxylation of a-keto acids [43] ... 

An interesting synthetic approach to thietanes is the selective desulfurization of cyclic disulfides.The treatment of dithiolanes with a diethyl-aminophosphine results in a ring contraction to thietanes, (Eq. 19). This has been demonstrated with a-lipoic acid, a coenzyme with a dithiolane structure involved in the biological oxidation of pyruvic acid. The reaction is proposed to be initiated by the electrophilic attack of the phosphorus on the ring sulfur atom, resulting in the formation of an acyclic internal phosphonium salt, which by subsequent elimination of a phosphine sulfide, closes to the four-membered ring. °... 

The second stage of cellular respiration, called the Kreb s cycle, also has several steps. The overall result is the oxidation of pyruvic acid to form CO2, as shown in the following equation. 

Lipoic acid (43) is another naturally occurring disulfide it is a growth factor and is the cofactor required for the enzymic oxidation of pyruvic acid in microorganisms. Lipoic acid (43) is an oxidising agent which is reduced to the thiol (44), and the latter can be subsequently reoxidised (Scheme 27). 

Compound derived from poppy seed oil. Inhibits oxidation of pyruvic acid, which accumulates in the blood. Used as antimicrobial to control dental disease but also toxic - cause of epidemic dropsy. 

An inhibitor for lactate dehydrogenase would block the formation of lactic acid or lactate, the main distinguishing feature of cancer cell metabolism. This would alternately favor the normal oxidation of pyruvic acid or pyruvate via the tricarbox-yhc acid cycle. As a quahlication, cancer cells also apparently undergo a degree of oxidative metabohsm, though the conversion to lactate or lactic acid occurs to a much greater extent. 

If oxidation occurs, as in normal cell metabolism, the overall oxidation of pyruvic acid and coproduct hydrogen can be viewed as... 

Gibson, G. E., et ak, 1975. Decreased synthesis of acetylcholine accompanying impaired oxidation of pyruvic acid in rat brain minces. Biochem J. 148, 17-23. 

Phosphorylation of this kind, involving electron transfer, is a process distinct from substrate-level phosphorylation, which can occur under anaerobic conditions. In this way energy-rich ATP is produced, and atmospheric oxygen is converted into water during the oxidation of pyruvic acid in the Krebs cycle. 

Chloramine T (CAT) oxidation of catechol in the presence and absence of surfactant cetylpyridinium bromide is first order in CAT, and the rate increases in the presence of surfactant. Rate laws have been reported for oxidation of pyruvic acid uncatalysed in acid medium and Os(VIII)-catalysed in alkaline medium. 

In addition to polyketides and mevalonic acid-derived species, acetyl-CoA moves through the TCA (or the citric acid cycle, or the Krebs cycle), a cycle (which by dehnition cannot have a beginning or end) that serves to produce many useful fragments as well as to effect the complete oxidation of pyruvic acid. As shown in Scheme 11.89, as acetyl-CoA enters the already turning cycle, an addition to the carbonyl group of oxaloacetate occurs (citrate synthase, EC 2.3.3.1) to produce citrate. In the addition process, the methyl group of the acetyl-CoA becomes the pw-S carbon in citrate. 

E. Racker The point which Dr. Hellerman has made, I think, is important. Not only the oxidation of pyruvic acid is dependent on SS groups, but a number of hormones like insulin and some pituitary hormones also depend on SS groups. It is not just a matter of keeping glutathione reduced in the cells but keeping the right balance between SH and SS groups. 

Study of the mechanism of the oxidation of pyruvic acid by certain bacteria led to the discovery of lipoic acid (thioctic acid) as a nutrient metabolite essential for the oxidative decarboxylation of a-keto acids. It subsequently was determined that the acetate-replacing factor " for lactic acid bacteria and protogen,a growth factor for the protozoan, Tetrahymena gelii, were also identical with lipoic acid. The occurrence of considerable quantities of lipoic acid in mammalian preparations of pyruvate and a-ketoglutarate oxidases suggests that it has the same function in animal tissues as in microorganisms. ... 

The coenzyme of carboxylase (thiamine pyrophosphate) was shown to be the active form of vitamin B, a method for its estimation was developed, its enzymatic synthesis in animal tissues was demonstrated. Perhaps the most important part of Ochoa s work at Oxford was the discovery of the coupling of phosphorylation with oxidation of pyruvic acid in brain. Here he demonstrated the obligatory relationship between these two processes, a contribution which came almost at the same time as the observations of Herman Kalckar in Denmark and Vladimir A. Belitzer in the Soviet Union. Ochoa was the first to show the formation of three phosphate bonds for each oxygen atom used in the process. 

The oxidation of pyruvic acid to form acetyl CoA was for many years the elusive active acetate . It was the target of active research in many laboratories since Peters demonstrated in the 1930s that cocarboxylase (thiamine pyrophosphate) is necessary for the process. The reaction implies an oxidative decarboxylation by which pyruvic acid loses CO2 and 2H to form acetyl CoA, and requires several enzymes and coenzymes (thiamine pyrophosphate, coenzyme A, NAD, lipoic acid and Mg +). 

With the collaboration of Seymour Kaufman, Ochoa obtained in 1952 a soluble preparation from heart muscle which showed a direct coupling between decarboxylative oxidation of a-ketoglutarate and ATP formation. This confirmed Ochoa s earlier results with particulate fractions. NAD and CoA were needed in the soluble system. Formation of succinyl-CoA as an intermediate, analogous to acetyl-CoA, was postulated, and the presence of this compound was quickly demonstrated in both his and David Green s laboratories. The mechanism of this reaction proved to be similar to that of the oxidation of pyruvic acid. 

Ochoa, S. (1941) Coupling of phosphorylation with oxidation of pyruvic acid in brain. J. Biol. Chem. 138,751. 

Evidence bearing on this question became available in 1941 from isotope experiments by Wood, Werkman, Hemingway, and Nier, and by Evans and Slotin, working with pigeon liver. The metabolism of this tissue is in many ways similar to that of pigeon muscle, as far as the oxidation of pyruvic acid is concerned, except that liver is capable of performing at least one additional reaction, the synthesis of oxalacetate from pyruvate and carbon dioxide - ... 

The imravelling of the sequence of chemical steps involved in the formation and oxidation of pyruvic acid has followed from studies of the chemical activities of plant extracts and of the individual enzymes isolated from such extracts. Such studies have now yielded a very detailed picture of the biochemical reactions involved in respiration have provided us with the essential biochemical foundation for a critical study of the process of respiration as it proceeds in the living cell. In this volume where our emphasis is on the metabolism of living cells a detailed consideration of the biochemistry of respiration or of any of the other vital aspects of metabolism would be inappropriate. Nevertheless, and just in so far as interpretation of cellular metabolism requires appreciation of the nature of the underlying chemical events we can properly draw upon the findings of biochemistry. 

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