Pyruvic acid

In 1834, Théophile-Jules Pelouze distilled tartaric acid and isolated glutaric acid and another unknown organic acid. Jöns Jacob Berzelius characterized this other acid the following year and named pyruvic acid because it was distilled using heat. The correct molecular structure was deduced by the 1870s. ==Production==

Pyruvic acid is prepared by treating tartaric acid with acid. It can also be produced by oxidation of propylene glycol by potassium permanganate or bleach. The hydrolysis of acetyl cyanide, formed by reaction of acetyl chloride with potassium cyanide, represents yet another route: : ==Structure==

Pyruvic acid crystallizes as the keto acid, not the enol. The six non-hydrogen atoms are nearly coplanar. More relevant to biochemistry is the structure of the pyruvate anion. Several salts of pyruvate have been examined by X-ray crystallography. These tests confirm that pyruvate anion also exists in the keto form. ==Reactivity==

As a simple, abundant and bifunctional compound, pyruvic acid has been shown to participate in many reactions. Pyruvate reacts with amino acids to give alanine by the process called transamination: : Pyruvic acid self-condenses to give zymonic acid, a cyclic dehydrated dimer: : The dehydration can be induced by distillation of pyruvic acid. Zymonic acid in turn forms a variety of derivatives in aqueous solution. Pyruvic acid is a precursor to several types of heterocycles. When treated with phenethylamine, it gives tetrahydroisoquinoline by a sequential condensation/acylation process (Bischler–Napieralski reaction). With ortho-phenylenediamine it condenses to give quinoxalines. Condensation with 4,5-diaminopyrimidine give hydroxypteridines. ==Biochemistry==

Pyruvate is important in biochemistry. It is the output of the metabolism of glucose known as glycolysis. One molecule of glucose breaks down into two molecules of pyruvate, These reactions are named after Hans Adolf Krebs, the biochemist awarded the 1953 Nobel Prize for physiology, jointly with Fritz Lipmann, for research into metabolic processes. The cycle is also known as the citric acid cycle or tricarboxylic acid cycle, because citric acid is one of the intermediate compounds formed during the reactions. If insufficient oxygen is available, the acid is broken down anaerobically, creating lactate in animals and ethanol in plants and microorganisms (and in carp). Pyruvate from glycolysis is converted by fermentation to lactate using the enzyme lactate dehydrogenase and the coenzyme NADH in lactate fermentation, or to acetaldehyde (with the enzyme pyruvate decarboxylase) and then to ethanol in alcoholic fermentation. Pyruvate is a key intersection in the network of metabolic pathways. Pyruvate can be converted into carbohydrates via gluconeogenesis, to fatty acids or energy through acetyl-CoA, to the amino acid alanine, and to ethanol. Therefore, it unites several key metabolic processes. , comparing blood content of pyruvate (shown in violet near middle) with other constituents. Pyruvic acid production by glycolysis In the last step of glycolysis, phosphoenolpyruvate (PEP) is converted to pyruvate by pyruvate kinase. This reaction is strongly exergonic and irreversible; in gluconeogenesis, it takes two enzymes, pyruvate carboxylase and PEP carboxykinase, to catalyze the reverse transformation of pyruvate to PEP. Decarboxylation to acetyl CoA Pyruvate decarboxylation by the pyruvate dehydrogenase complex produces acetyl-CoA. Carboxylation to oxaloacetate Carboxylation by pyruvate carboxylase produces oxaloacetate. Transamination to alanine Transamination by alanine transaminase produces alanine. Reduction to lactate Reduction by lactate dehydrogenase produces lactate. Environmental chemistry Pyruvic acid is an abundant carboxylic acid in secondary organic aerosols. ==Uses==

Aside from its major role in the functioning of living organisms, pyruvic acid is of interest as a reagent in the synthesis of specialized organic compounds as discussed above in the reactivity section. == See also ==