Subject pyruvate

Variety of a-keto esters, such as methyl and ethyl pyruvate, methyl mandalate, dihydro-4,4 - dimethyl-2,3 fiiranedione were used to calculate the shielded form of [CDdosed - a-keto ester] complexes leading to the formation of ( R) or (S) product, respectively. The details of these results will be a subject of a subsequent paper [17]. As emerges from these calculations the favourable directionality is maintained in complexes (R), even for dihydro-4,4 - dimethyl-2,3 fiiranedione. 

VI. Valentine, W. N Tanaka, K. R., and Miwa, S A specific erythrocyte glycolytic enzyme defect (pyruvate kinase) in three subjects with congenital non-spherocytic hemolytic anemia. Trans. Assoc. Am. Physicians 74, 100-110 (1961). 

The enantioselective hydrogenation of oc,p-unsaturated acids (or their esters) and a-ketoesters, mainly pyruvates, (Figure 1) is a subject of high industrial relevance in the pharmaceutical and agrochemical areas, considering the very different activity of pure enantiomers (1,2). However, the former reaction has been up to today less investigated, evidencing a lower enantioselectivity (maximum ee 38% in comparison to 90% for the ethyl pymvate) (3,4). 

The addition of an enolsilane to an aldehyde, commonly referred to as the Mukaiyama aldol reaction, is readily promoted by Lewis acids and has been the subject of intense interest in the field of chiral Lewis acid catalysis. Copper-based Lewis acids have been applied to this process in an attempt to generate polyacetate and polypropionate synthons for natural product synthesis. Although the considerable Lewis acidity of many of these complexes is more than sufficient to activate a broad range of aldehydes, high selectivities have been observed predominantly with substrates capable of two-point coordination to the metal. Of these, benzy-loxyacetaldehyde and pyruvate esters have been most successful. 

Photolytic. Dalapon (free acid) is subject to photodegradation. When an aqueous solution (0.25 M) was irradiated with UV light at 253.7 nm at 49 °C, 70% degraded in 7 h. Pyruvic acid is formed which is subsequently decarboxylated to acetaldehyde, carbon dioxide, and small quantities of 1,1-dichloroethane (2-4%) and a water-insoluble polymer (Kenaga, 1974). The photolysis of an aqueous solution of dalapon (free acid) by UV light (X = 2537 A) yielded chloride ions, carbon dioxide, carbon monoxide, and methyl chloride at quantum yields of 0.29, 0.10, 0.02, and 0.02, respectively (Baxter and Johnston, 1968). 

The most important factor in the regulation of the cycle is the NADH/NAD ratio. In addition to pyruvate dehydrogenase (PDH) and oxoglu-tarate dehydrogenase (ODH see p. 134), citrate synthase and isodtrate dehydrogenase are also inhibited by NAD deficiency or an excess of NADH+HT With the exception of isocitrate dehydrogenase, these enzymes are also subject to product inhibition by acetyl-CoA, suc-cinyl-CoA, or citrate. 

With the exception of lactate and pyruvate, the differences in levels of these acids emanating from the skin of the subjects did not vary too greatly between our small groups of representatives of the different sexes. The statistical and socio-sexual significance of these results notwithstanding, the above study has demonstrated the chemical complexity of cutaneous emissions even prior to the application of natural or artificially formulated scents and fragrances. 

Three glycolytic enzymes are subject to allosteric regulation hexoldnase IV, phosphofructokinase-1 (PFK-1), and pyruvate kinase. 

Experiments with rats have shown that the branched-chain a-keto acid dehydrogenase complex is regulated by covalent modification in response to the content of branched-chain amino acids in the diet. With little or no excess dietary intake of branched-chain amino acids, the enzyme complex is phosphorylated and thereby inactivated by a protein kinase. Addition of excess branched-chain amino acids to the diet results in dephosphoiylation and consequent activation of the enzyme. Recall that the pyruvate dehydrogenase complex is subject to similar regulation by phosphorylation and dephosphorylation (p. 621). 

Subject Phenylacetic Acid Mandelic Acid o-Hydroxy- phenylacetic Acid Phenyllactic Acid Phenyl- pyruvic Acid p-Hydroxy- phenylacetic Acid... 

Further developments are shown in Figure 4. On the basis that glucosamine reacted with pyruvic acid in the presence of alkali to yield pyrrole-2-carboxylic acid, in 1% yield, Gottschalk (21) proposed that sialic acid was formed by an aldol condensation reaction between N-ace-tylglucosamine and pyruvic acid. Kuhn and Brossmer (15) and Zilliken and Glick (22) showed that the reverse reaction also took place under alkaline conditions. Cornforth, Firth, and Gottschalk (23) synthesized crystalline N-acetylneuraminic acid (NANA) from N-acetylglucosamine and oxaloacetic acid (pH 11, 20°C). Under conditions less subject to misinterpretation, Heimer and Meyer (24) found that Vibrio cholerae enzymes cleaved NANA into an N-acetylhexosamine and pyruvic acid. 

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