Pyruvic acid 3-phosphate

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. 

Several of the intracellular teichoic acids are polymers of glycerol phosphate or ribitol phosphate. An unusual teichoic acid, composed of d-mannitol phosphate, and with pyruvic acid linked as an acetal to 0-4 and 0-5, has been isolated from Brevibacterium iodinum. ... 

A. Phosphoenolpyruvate.—The mechanisms of hydrolysis of phosphate esters of phosphoenol pyruvic acid (33) have been described in detail, and 0 studies confirm an earlier postulate that attack by water on the cyclic acyl phosphate (34) occurs at phosphorus and not at carbon. In the enolase reaction, the reversible interconversion of 2-phosphoglyceric acid(35)... 

Citraconic anhydride (Methyl maleic anhydride) was found to be produced from pyruvic acid by an oxidative decarboxy-condensation. The best catalyst is iron phosphate with a P/Fe atomic ratio of 1.2. The presence of oxygen is required to promote the reaction. The main side-reaction is formation of acetic acid and CO2 by oxidative C-C bond fission. The best results are obtained at a temperature of 200°C. The yield of citraconic anhydride reaches 71 mol% at a pyruvic acid conversion of 98%. 

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]. 

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. 

The reaction was studied using the iron phosphate catalyst at 230°C with feed rates of pyruvic acid, air, and water = 10.5, 350, and 480 mmol/h. The main products were citraconic anhydride, acetic acid, and CO2. When the amount of catalyst used was lOg, that is, when the contact time is about 2.6 s, the conversion of pyruvic acid reached 95% and the yields of citraconic anhydride and acetic acid were 50 and 28 mol%, respectively the loss was about 17 mol%. The selectivity to citraconic anhydride is clearly lower and that to acetic acid is higher than in the case of the W-based oxide catalysts. However, the catalytic activity was very stable. No clear change in the yield of citraconic anhydride was observed during the reaction for 10 h. 

The reaction was performed over the iron phosphate catalyst by changing the feed rate of oxygen from zero to 350 mmol/h, while fixing the sum of feed rates of oxygen and nitrogen at 350 mmol/h. The feed rate of pyruvic acid was fixed at 10.5 mmol/h. The yields of citraconic anhydride obtained at a temperature of 230°C and a short contact time of 0.52 s (amount of catalyst used = 2 g) are plotted as a function of the feed rate of oxygen in Figure 3. 

As may be seen in Figures 5 and 6, when iron phosphate is used as the catalyst, the selectivity is dependent largely on the reaction temperature. Therefore, the activation energy for the citraconic anhydride formation is considered to be much lower than that for the acetic acid formation. Indeed, the selectivity to acetic acid decreases steadily with a decrease in the temperature. However, the selectivity to citraconic anhydride shows a maximum at about 200 C. Possibly, the vaporization of pyruvic acid may become difficult at temperatures below 200°C. 

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. 

From Sigma 3-aminoethylcarbazole (AEC) acrylamide/bis-acrylamide (30%) 37.5 1 amino acids alumina bentonite benzamidine bovine fiver tRNA bovine serum albumin (BSA) creatine phosphate (CP) diethyl pyrocarbonate (DEPC) dithiothreitol (DTT) Escherichia coli MRE600 tRNA pyrophosphatase (Ppase) Ca++ salt of folinic acid, (5-formyl THF) IIHPHS K salt of phospho-enol pyruvic acid, (PEP) creatine phospho kinase (CPK) protease inhibitor cocktail for fungal and yeast extracts phenylmethylsulfonyl fluoride (PMSF) spermidine trihydrochloride Tween 20. 

The CPPase substrate DMAPP (15) is formed from isopentenyl pyrophosphate (IPP) (14) via the IPP isomerase reaction. It had been assumed that IPP was generated only via mevalonic acid (12) (Fig. 2), but Rohmer discovered another route, 2-C-methyl-D-erythritol 4-phosphate (13) (MEP) pathway (Fig. 2) [22, 23]. A key step in the MEP pathway is the reaction catalyzed by 1-deoxy-D-xylulose 5-phosphate synthase (DXS), which combines hydroxyethyl thiamine pyrophosphate (hydroxyethyl TPP) generated from pyruvic acid (17) and TPP with glyceral-dehyde 3-phosphate (18) to yield 1-deoxy-D-xylulose 5-phosphate (19) containing five carbons. The mevalonate pathway operates in the cytosol of plants and animals, whereas the MEP pathway is present in the plastid of plants or in eubacteria [24-27]. 

In addition to the catalysts listed in Table 2, several rhodium(I) complexes of the various diphosphines prepared by acylation of bis(2-diphenylphosphinoethyl)amine were used for the hydrogenation of unsaturated acids as well as for that of pyruvic acid, aUyl alcohol and flavin mononucleotide [59,60]. Reactions were mn in 0.1 M phosphate buffer (pH = 7.0) at 25 °C under 2.5 bar H2 pressure. Initial rates were in the range of 1.6-200 mol H2/molRh.h. 

Once the phosphate ester is hydrolysed, there is an immediate rapid tautomerism to the keto form, which becomes the driving force for the metabolic transformation of phosphoenolpyruvic acid into pyruvic acid, and explains the large negative free energy change in the transformation. This energy release is coupled to ATP formation (see Box 7.25). 

Hydroxycyclopropanecarboxylic acid phosphate HCP 34 is an analogue of phosphoenolpyruvate (PEP) 35 which is metabolized by various enzymes. HCP 34 is a potent competitive inhibitor of enzymes utilizing PEP 35, such as PEP carboxylase, enolase, pyruvate kinase, and probably other enzymes. It is a substantially better inhibitor than phospholactate 36 or phosphoglycolate 37, presumably because of the similarity of its geometric and electronic structures with phosphoenol pyruvate,Eq. 12 [28]. 

Figure 21. Secondary metabolism blocks and amino acid derivation. Note that shikimic acid can be derived directly from photosynthesis and glycolysis through the pentose phosphate cycle, or alternatively as a pyruvic acid postcursor.

The vapor-phase oxidation of lactic acid with air was executed using an iron phosphate catalyst with a P/Fe atomic ratio of 1.2. It was found that lactic acid is selectively converted to form pyruvic acid by oxidative dehydrogenation. The one-pass yield reached 50 mol% however, acetaldehyde, acetic acid, and CO2 was still formed, and the pyruvic acid produced decomposes over time to give acetic acid and C02. ... 

Hayami and his coworkers have studied the mechanism of formation of acetol and pyruvic acid from D-glucose- -14C, -6-14C, and -3,4-14C2, reacting in a concentrated, phosphate buffer solution.148-151 Their data supported the supposition that the products are formed from pyruvaldehyde by way of a Cannizarro reaction. As in the formation of lactic acid, the pyruvaldehyde can be formed either from the reducing or the nonreducing end of the D-glucose molecule, and the distribution of radioactivity in the pyruvic acid and acetol... 

Recently Benkovic and Schrayl28b and Clark and Kirby,26c have investigated the hydrolysis of dibenzylphosphoenolpyruvic acid and mono-benzylphospho-enolpyruvic acid which proceed via stepwise loss of benzyl alcohol (90%) and the concomitant formation of minor amounts (10%) of dibenzylphosphate and monobenzylphosphate, respectively. The pH-rate profiles for release of benzyl alcohol reveal that the hydrolytically reactive species must involve a protonated carboxyl group or its kinetic equivalent. In the presence of hydroxylamine the course of the reaction for the dibenzyl ester is diverted to the formation of dibenzyl phosphate (98%) and pyruvic acid oxime hydroxamate but remains unchanged for the monobenzyl ester except for production of pyruvic acid oxime hydroxamate. The latter presumably arises from phosphoenolpyruvate hydroxamate. These facts were rationalized according to scheme (44) for the dibenzyl ester, viz. 

In the biosynthesis of the capsular polysaccharide from Xanthomonas campestris, the modification was shown265 to occur at the level of a polyprenyl pentasaccharide diphosphate intermediate prior to polymerization of the repeating units, and enolpyruvate phosphate was a precursor of the pyruvic acid residues. A similar observation was made during a study of the biosynthesis of Rhizobium meliloti exopolysaccharide.266... 

In order for the cell to carry out a controlled oxidation of D-glucose and conserve some of the energy derived from the process, it is lira necessary to add phosphate to the hexose with the expenditure of energy. The necessary energy and the phosphate per se is supplied by ATP in two separate reactions of the system. Since each molecule of glucose can yield two molecules of irioxe phosphate for oxidation, the conversion of glucose in pyruvic acid nets two molecules of ATP per molecule of hexose utilized. 

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