Pyruvic acid -lactic

The characteristic feature of carbohydrate breakdown in cestodes is the production of a range of complex end-products, usually organic acids, even under aerobic conditions (Table 5.4). This contrasts with predominantly aerobic organisms, such as most free-living metazoa, where the end-product of glycolysis is almost exclusively lactic acid formed from pyruvic acid. Lactic acid is produced as a result of rapid muscular contraction carried out essentially under anaerobiosis and its production ensures a rapid expenditure of energy without the limitation due to the rate of diffusion of oxygen. The anaerobic phase is followed by an aerobic phase, where pyruvic acid is metabolised to acetyl-coenzyme A which is in turn oxidised completely to... 

E. Bohle, and R. Biegler Humoral changes in arteriosclerosis. Investigation on lipids, fatty acids, ketone bodies, pyruvic acid, lactic acid, and glucose in the blood. Lancet 1960/11, 1409. 

The biological standard potential of the couple pyruvic acid/ lactic acid is-0.19 V. What is the thermodynamic standard potential of the couple Pyruvic acid is CH3COCOOH and lactic acid is CH3CH(0H)C00H. 

The biological standard potential of the redox couple pyruvic acid/lactic acid is -0.19 V and that of the fumaric acid/succinic acid couple is -tO.03 V at 298 K. What is the equilibrium constant at pH = 7 for the reaction... 

In this fashion, under the more or less direct action of cysteine desulf-hydrase, cysteine gives rise to C3 molecules, namely pyruvic acid, lactic acid, and alanine. The compounds can easily change one to the other in the tissue. The formation of these molecules establishes the link between the metabolism of cysteine and the carbohydrate metabolism, and explains, among other things, that cysteine must be the generator of extra glucose in phlorizinized dogs (31). 

IS the oxidation of lactic acid to pyruvic acid by NAD and the enzyme lactic acid coenzyme NAD ... 

Enzyme catalyzed reductions of carbonyl groups are more often than not com pletely stereoselective Pyruvic acid for example is converted exclusively to (5) (+) lactic acid by the lactate dehydrogenase NADH system (Section 15 11) The enantiomer... 

The enzyme is a single enantiomer of a chiral molecule and binds the coenzyme and substrate m such a way that hydride is transferred exclusively to the face of the carbonyl group that leads to (5) (+) lactic acid Reduction of pyruvic acid m the absence of an enzyme however say with sodium borohydride also gives lactic acid but as a racemic mixture containing equal quantities of the R and S enantiomers... 

In spite of the number of different structural types lipids share a common biosyn thetic origin m that they are ultimately derived from glucose During one stage of car bohydrate metabolism called glycolysis glucose is converted to lactic acid Pyruvic acid IS an intermediate... 

Dilute (0-1n-0-001n) acetic, propionic, butyric, succinic and lactic acids all corrode lead to about the same extent. Pyruvic acid appears to inhibit corrosion after a short period of attack. In most cases the corrosion products are x PbCOj, y Pb(OH)2, the ratio of ar to being 2 1, and corrosion is intergranular . ... 

Reactions involve several enzymes, which have to follow in sequence for lactic acid and alcohol fermentation. This is known as the glucose catabolism pathway, with emphasis on energetic and energy carrier molecules such as ATP, ADP, NAD+ and NADH. In this pathway the six-carbon substrate yields two three-carbon intermediates, each of which passes through a sequence of reactions to the stable end product of pyruvic acid. 

The acidic sugars discussed in this Section are glycuronic acids and glycu-losonic acids. Bacterial polysaccharides may also become acidic by substitution of sugar residues, for example by etherification with lactic acid, acetala-tion with pyruvic acid, or phosphorylation, and these possibilities will be discussed in the following Sections. A sugar that does not fall into any of... 

Some sugar residues in bacterial polysaccharides are etherified with lactic acid. The biosynthesis of these involves C)-alkylation, by reaction with enol-pyruvate phosphate, to an enol ether (34) of pyruvic acid, followed by reduction to the (R) or (5) form of the lactic acid ether (35). The enol ether may also react in a different manner, giving a cyclic acetal (36) of pyruvic acid. 

Pyruvic acid is the simplest homologue of the a-keto acid, whose established procedures for synthesis are the dehydrative decarboxylation of tartaric acid and the hydrolysis of acetyl cyanide. On the other hand, vapor-phase contact oxidation of alkyl lactates to corresponding alkyl pyruvates using V2C - and MoOa-baseds mixed oxide catalysts has also been known [1-4]. Recently we found that pyruvic acid is obtained directly from a vapor-phase oxidative-dehydrogenation of lactic acid over iron phosphate catalysts with a P/Fe atomic ratio of 1.2 at a temperature around 230°C [5]. 

The one-pass yield of pyruvic acid reached 50 mol%. The main side reactions are the formation of acetaldehyde and CO2 by oxydative C-C bond fission of lactic acid and that of acetic acid and CO2 by oxidative C-C bond fission of the produced pyruvic acid. 

In the reaction of lactic acid to form pyruvic acid over the iron phosphate catalysts, formation of a new compound was observed. As the extent of reaction increased, the amount of pyruvic acid increased to a maximum and then decreased, while that of the new compound increased steadily. It was therefore concluded that the new compound is formed from pyruvic acid in parallel with acetic acid and CO2. According to gas-mass analyses, the molecular weight was determined as 112. However, there are many compounds with molecular weigth of 112. After the NMR analyses and X-ray diffraction analyses for the single crystal, the new compound was determined to be citraconic anhydride, i.e., mono-methyl maleic anhydride. 

Since formation of citraconic anhydride from pyruvic acid is one of "acid to acid type" transformations, such as reactions from isobutyric acid to methacrylic acid and from lactic acid to pyruvic acid, the required catalysts must be acidic [11). If the catalysts are basic, it may be impossible to obtained acidic products, because basic catalysts activate selectively acidic molecules and, as a result, they show a very high activity for the decomposition of acidic products [11]. 

Other difunctional aliphatic carboxylic acids, e.g. lactic add, pyruvic acid, ethoxyacetic acid. 

Nonvolatile acids Lactic, pyruvic, oxalic, tartaric, citric acids 0.4 0.4... 

During the recovery period from exercise, ATP (newly produced by way of oxidative phosphorylation) is needed to replace the creatine phosphate reserves — a process that may be completed within a few minutes. Next, the lactic acid produced during glycolysis must be metabolized. In the muscle, lactic acid is converted into pyruvic acid, some of which is then used as a substrate in the oxidative phosphorylation pathway to produce ATP. The remainder of the pyruvic acid is converted into glucose in the liver that is then stored in the form of glycogen in the liver and skeletal muscles. These later metabolic processes require several hours for completion. 

Methyl pyruvate has been prepared from the silver salt of pyruvic acid and methyl iodide,3 and from the free acid by the alcohol-vapor method without a catalyst.4 Pyruvic esters have also been prepared by the dehydrogenation of lactic acid esters.5... 

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