Acetyl-pyruvic acid

Addition of 2-pyrazolines to tetrazines gave 330 (84AP237 88CZ17). The pyrazolotriazine derivative 331 was prepared (76MI6) by treating diamino guanidine with acetyl pyruvic acid ethyl ester in either acid or neutral aqueous solution (Scheme 70). 

TV-Acetyl neuraminic acid aldolase [from Clostridium perfringens, TV-acetyIneuraminic acid pyruvate lyase] [9027-60-5] 32,000 [EC 4.1.3.3]. Purified by extraction with H2O,... 

In general, pyruvate decarboxylase (EC 4.1.1.1) catalyzes the decarboxylation of a 2-oxocar-boxylic acid to give the corresponding aldehyde6. Using pyruvic acid, the intermediately formed enzyme-substrate complex can add an acetyl unit to acetaldehyde already present in the reaction mixture, to give optically active acetoin (l-hydroxy-2-butanone)4 26. Although the formation of... 

Pyruvic Acid (2-O.xopropanoic Acid, Acetyl-formic Acid, Pyroracemic Acid, Brenztrau-bensaure in Ger), CH3COCOOH, mw 88.06, colorl liq, mp 11.8°, bp 165° decomps, d 1.267 g/cc at 15/4°, Miscible with w, ale eth. Polymerizes and decomps on standing unless pure and kept in container with airtight closure. 

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]. 

Fig. 19. Reaction scheme for the electrochemically driven enzymatic carboxylation of acetyl-SCoA to form pyruvic acid...

Anker,3 5 using isotope tracer technique, found in a mixed laboratory strain of rats (Wistar) no significant conversion of pyruvic acid to acetic acid. This was in contrast to the results obtained with the Sprague-Dawley strain of rats in which either such a conversion did take place or else pyruvic acid was utilized directly for acetylation. Exactly what constitutes the enzymic difference between the two strains is not known, but it is clear that a striking and potentially important difference exists. From the genetic standpoint one should not expect precisely the same metabolic results from rats of different strains or even from individual rats within the same strain, but the difference here reported is perhaps more fundamental than one might anticipate. If this difference is real, presumably other differences exist which have not been looked for, and one should be extremely careful about accepting the results from one strain as applicable to another. 

In this reaction, pyruvic acid is oxidized to carbon dioxide with formation of acetyl-SCoA and NAD+ is reduced to NADH. As noted in chapter 15, this reaction requires the participation of thiamine pyrophosphate as coenzyme. Here too the NADH formed is converted back to NAD+ by the electron transport chain. As noted above, the acetyl-SCoA is consumed by the citric acid cycle and CoASH is regenerated. 

The homolytic acylation of protonated heteroaromatic bases is, as with alkylation, characterized by high selectivity. Only the positions a and y to the heterocyclic nitrogen are attacked. Attack in the position or in the benzene ring of polynuclear heteroaromatics has never been observed, even after careful GLC analysis of the reaction products. Quinoline is attacked only in positions 2 and 4 the ratio 4-acyl- to 2-acylquinoline was 1.3 with the acetyl radical from acetaldehyde, 1.7 with the acetyl radical from pyruvic acid, and 2.8 with the benzoyl radical from benzaldehyde. 

This enzyme [EC 4.1.3.3], also known as A-acetylneu-raminate aldolase, will convert A-acetylneuraminate to A-acetylmannosamine and pyruvate. The enzyme will also act on A-glycoloylneuraminate and on O-acetylated sialic acids, other than O -acetylated derivatives. 

A-Acetyl neuraminic acid aldolase [from Clostridium perfringens, A-acetylneuraminic acid pyruvate lyase] [9027-60-5] [EC 4.1.3.3]. Purified by extraction with H20, protamine pptn, (NH4)2S04 pptn, Me2CO pptn, acid treatment at pH 5.7 and pptn at pH 4.5. The equilibrium constant for pyruvate + n-acetyl-D-mannosamine ++ /V-acetylneuraminidate at 37° is 0.64. The Km for A-acetylneuraminic acid is 3.9mM in phosphate at pH 7.2 and 37°. [Comb and Roseman Methods in Enzymology 5 391 1962). The enzyme from Hogg kidney (cortex) has been purified 1700 fold by extraction with H20, protamine sulphate pptn, (NH4)2S04 pptn, heat treatment between 60-80°, a second (NH4)2S04 pptn and starch gel electrophoresis. The Km for A-acetylneuraminic acid is 1.5mM. [Brunetti et al. JBC 237 2447 1962). 

O-acetyl-a-D-mannopyranosyl unit. About half of the terminal P-D-mannopyranosyl units carry a pyruvic acid group as a 4,6-di-O-acetal. The molecular weight is probably on the order of 2 x 106 daltons, although much higher figures have been reported. 

Pyruvic acid Coenzyme A Oxidized form of nicotinamide adenine dinucleotide Acetyl coenzyme A Reduced form of nicotinamide adenine dinucleotide Carbon Proton dioxide... 

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