Pyruvic acid effects

CH3CO(CH2)2COOH, 1 AHCl, 25°, 3 h, 94% yield. Pyruvic acid (HOAc, reflux, 1-3 h, 77% yield) and acetone (80-100 h, 72% yield) effect cleavage in a similar manner. 

A uniformly favorable effect is displayed by an alkyl group, in position 2. Thus the 2-methylthiosemicarbazone of pyruvic acid is cyclized at normal temperature and without excess hydroxide. The 2-methylthiosemicarbazone of glyoxylic acid (98) was cyclized by boiling for 5 min to 2-methyl-3-thioxo-5-oxo-2,3,4,5-tetrahydro-... 

The cyclization of the 4-methylthiosemicarbazone of pyruvic acid was recently effected by refluxing in dimethylformamide, ... 

Romero, C. and Bakker, J., Interactions between grape anthocyanins and pyruvic acid, with effect of pH and acid concentration on anthocyanin composition and color in model solutions, J. Agric. Food Chem., 47, 3130, 1999. 

Si-P and Si-AI are not effective, either. The basic catalyst such as Si-K is very active for decomposition of pyruvic acid, but citraconic anhydride is not produced. The best results are obtained with W and W-based catalyst. The one-pass yield of citraconic anhydride reaches about 60 mol% at a pyruvic acid conversion of about 92%. The combination of P to W decreases the activity markedly. The combination of Mo or K decreases the selectivity to citraconic anhydride. The combination of Ti or Sn is scarcely effective, when the amount is less than 10 atomic %. When the amount of Sn or Ti is high, the selectivity falls. 

Pyrophosphates, diaryl, effect of cycloamyloses on hydrolysis of, 23 235 Pyrophyllite, idealized formula, 33 337 Pyruvic acid... 

Enols and enolization feature prominently in some of the basic biochemical pathways (see Chapter 15). Biochemists will be familiar with the terminology enol as part of the name phosphoenolpyruvate, a metabolite of the glycolytic pathway. We shall here consider it in non-ionized form, i.e. phosphoenolpyruvic acid. As we have already noted (see Section 10.1), in the enolization between pyruvic acid and enolpyruvic acid, the equilibrium is likely to favour the keto form pyruvic acid very much. However, in phosphoenolpyruvic acid the enol hydroxyl is esterified with phosphoric acid (see Section 7.13.2), effectively freezing the enol form and preventing tautomerism back to the keto form. 

In some cases a choice of multicomponent or linear protocol for the treatment of pyruvic acids, aminoazole, and aldehydes allows obtaining different heterocycles. For instance, MCR involving 5-aminopyrazoles or sequence pathway via preliminary synthesis of arylidenpyruvic acids led to positional isomers 36 and 37, respectively (Scheme 15) [4, 61, 68]. It is interesting to note that the same strategy applied to 3-amino-l,2,4-triazole or to amino-W-aryl-lH-pyrazole-4-carboxamide reactions gave no effect and the final compound for both the protocols were the same [52, 61, 62]. 

In a series of transition metal oxide semiconductor powders, photochemical activity in the decarboxylation of oxalic acid was controlled by surface properties and the presence of recombination centers, which in turn depended on the preparation method Similar effects have also been noted in the photodecarboxylation of pyruvic acid and formic acid... 

Practical and fundamental aspects of malo-lactic fermentation are given. Conditions which winemakers can use for better control of the fermentation, including detailed procedures for inoculation with Leuconostoc oenos ML 34 and for inhibition with fumaric acid, are presented. New information on the role of malic acid decarboxylation in bacterial metabolism and on the enzymatics of malic acid decarboxylation are reviewed. The malic acid decarboxylation seems to involve two pathways a direct decarboxylation of malic to lactic acid with NAD as a coenzyme and a concurrent but small oxidative decarboxylation to pyruvic acid and NADH. How these pathways can bring about the marked stimulation of bacterial growth rate by the malo-lactic reaction and their negligible effect on growth yield are discussed. 

If the total reaction is a simple decarboxylation of malic acid to lactic acid, it is difficult to understand how the utilization of malic acid can influence cell growth. Carbon dioxide also has been shown to stimulate growth of L. oenos ML 34 (84), yet it would seem the carbon dioxide formed from the reaction would be superfluous in new wine already saturated with it. In the original conception of the pathway, the reaction was considered as two stages with pyruvic acid and reduced NAD (NADH) as intermediates (72). Morenzoni (71) discussed the research and thinking (4, 85, 86, 87) which lead to the belief that there was only one step in the reaction and no formation of NADH or pyruvic acid as intermediates. However, any evidence to show a real formation of pyruvic acid would help explain the stimulatory effect of the reaction on cellular metabolism. 

The solvent deuterium isotope effect in the reaction of 359 with glyoxylate decreases from ( H2o/ D2o) °f 1-66 to ( H2o/ D2o) °f 1-12 with increasing pH from 1.25 to 6.43, respectively. 361 probably decarboxylates via a cyclic transition state. Transfer of the carboxylic proton takes place simultaneously with heavy-atom reorganization as indicated by small solvent DIE in the acid-catalysed reaction. The solvent DIE h2o/ D20 °f 1-20 at 1. M H+, observed in the reaction of 359 with pyruvic acid, is similar to the reaction of pyruvic acid with nitrosobenzene for which nucleophilic attack of nitroso nitrogen has been proposed395. 

The oscillatory behavior of product-inhibited cultures cannot simply be described by a common inhibition term in the equation for the biomass growth. A better description must include an indirect or delayed effect of the product ethanol on the biomass growth rate as indicated in experiments. The decay rate pmaa was introduced to account for the accumulation of the inhibitory product pyruvic acid. Other more mechanistic, structured models can be formed that relate to the internal key-compound e. In these, the inhibitory action of ethanol is accounted for in the inhibition of the key-compound e formation. Mathematically, however, these two model descriptions are equivalent, except that the key-compound e is washed out as a part of the biomass in continuous cultures and the rate constant //ma55 does not vary. Our proposed indirect inhibition model provides a good qualitative description of the experimental results shown in Figure 7.25. 

Proteinoids catalyze the decarboxylation of oxaloacetic acid to pyruvic acid, lysine-rich proteinoid being the most effective of these tested. Some are about 15 times more active than the equivalent amount of free lysine. Acidic proteinoids exhibit very little activity18). 

Berberine inhibits oxidative decarboxylation of yeast pyruvic acid (310) the same dose has, however, no effect upon aerobic glycolysis, Warburg s respiratory enzymes, indophenol oxidase, etc. Berberine and tetrahydroberberine have an inhibitory effect on oxidation of (+ )-alanine in rat kidney homogenates (498). Berberine and palmatine show a specific inhibitory effect upon cholinesterase in rabbit spleen and on pseudocholinesterase in horse serum (499). Berberine inhibits cellular respiration in ascitic tumors and even in tissue cultures (500-502). The specific toxic effect of berberine on the respiration of cells of ascitic tumors in mice was described (310). The glycolysis was not found to be affected, but the uptake of oxygen was smaller. Fluorescence was used in order to demonstrate berberine in cellular granules. Hirsch (503) assumed that respiration is inhibited by the effect of berberine on the yellow respiratory enzymes. Since the tumorous tissue contains a smaller number of yellow respiratory enzymes than normal tissue it is more readily affected by berberine. Subcutaneous injections of berberine, palmatine, or tetrahydropalmatine significantly reduce the content of ascorbic acid in the suprarenals, which is not affected by hypophysectomy (504). 

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