Pyruvic Acid Meaning
With a carboxylic acid and a ketone functional group, pyruvic acid (CH3COCOOH) is the most basic of the alpha-keto acids. Pyruvic acid (CH3COCOOH) is an organic acid found in almost all living organisms. It ionizes to form hydrogen ions and an anion. This anion is known as pyruvate. Pyruvate and pyruvic acid are almost interchangeable terms among biochemists. This article will study the pyruvate definition, pyruvate chemical formula, the chemical formula of pyruvic acid, pyruvic acid to lactic acid and the difference between pyruvate and pyruvic acid.
Physical Properties-
Pyruvic Acid Formula- C3H4O3
Molar mass- 88.06 g/mol
Density- 1.250 g/cm³
Melting point- 11.8 °C (53.2 °F; 284.9 K)
Boiling point- 165 °C (329 °F; 438 K)
Acidity (pKa)- 2.50
Pyruvic Acid Structure
[Image will be Uploaded Soon]
Synthesis of Pyruvic Acid
Jöns Jacob Berzelius obtained pyruvic acid, formerly known as pyroracemic acid, by dry distillation of tartaric acid in 1835. Tartaric acid is heated with fused potassium hydrogen sulphate at 210–220 °C to make pyruvic acid in bulk quantities. Fractional distillation under reduced pressure is used to purify the sample. Pure pyruvic acid is a colourless liquid with a pungent odour similar to acetic acid at room temperature. It forms crystals as it cools and melts at 13.6 °C. The boiling point is 165 degrees Celsius.
What is Pyruvic Acid?
Pyruvic acid is a central substance at the crossroads of carbohydrate, fat, and protein catabolism (breaking down) and anabolism (synthesis).
Pyruvic acid may be made from glucose, converted back to carbohydrates (such as glucose) through gluconeogenesis, or converted to fatty acids via an acetyl-CoA reaction. It can also be used to make the amino acid alanine, and it can be fermented to produce ethanol or lactic acid.
Five metabolic processes share a complex sequence of enzyme reactions that lead from sugar (or carbohydrate, in the form of glucose or fructose) to pyruvate.
They are:
yeast fermentation of sugar to ethyl alcohol;
muscle fermentation of sugar to lactic acid;
the Krebs cycle's oxidation of sugar to carbon dioxide and water;
sugar conversion to fatty acids; and
sugar conversion to amino acids, such as alanine, which are the building blocks of proteins.
Pyruvic Acid to Lactic Acid
When oxygen is present (aerobic respiration), pyruvic acid provides energy to living cells through the citric acid cycle (also known as the Krebs cycle); when oxygen is not present, it ferments to produce lactic acid. Pyruvate is a biochemically essential chemical compound. It's the product of glycolysis, which is anaerobic glucose metabolism. One molecule of glucose is broken down into two molecules of pyruvate, which are then used in one of two ways to provide additional energy.
Pyruvate is converted to acetyl-coenzyme A, which is the key input for the Krebs cycle, a sequence of reactions. An anaplerotic reaction converts pyruvate to oxaloacetate, which replenishes Krebs cycle intermediates and is often used for gluconeogenesis. These reactions are named after Hans Adolf Krebs, a biochemist who shared the Nobel Prize in Physiology with Fritz Lipmann in 1953 for his work on metabolic processes. Since citric acid is one of the intermediate compounds produced during the reactions, the cycle is also known as the citric acid cycle or tricarboxylic acid cycle.
When there isn't enough oxygen, the acid is broken down anaerobically, resulting in lactate in animals and ethanol in plants and microbes. Lactate fermentation uses the enzyme lactate dehydrogenase and the coenzyme NADH to convert pyruvate from glycolysis to lactate. In alcoholic fermentation, it is converted to acetaldehyde and then to ethanol.
Pyruvate is a significant intersection in the metabolic network. Pyruvate can be converted to carbohydrates through gluconeogenesis, fatty acids or energy via acetyl-CoA, amino acid alanine, and ethanol through gluconeogenesis. As a result, it connects a number of important metabolic processes.
Difference Between Pyruvate and Pyruvic Acid
Did You Know?
Glycolysis is a metabolic pathway that transforms glucose (C₆H₁₂O₆) into pyruvate (CH₃COCOO) and a hydrogen ion (H⁺). The free energy released during this process is used to create the high-energy molecules ATP (adenosine triphosphate) and NADH (nicotinamide adenine dinucleotide diphosphate) (reduced nicotinamide adenine dinucleotide). Glycolysis is a ten-step process involving enzymes. Fructose and galactose are two monosaccharides that can be converted to one of these intermediates. Instead of being used as phases in the overall reaction, the intermediates could be used directly.
FAQs on Pyruvic Acid
1. What is pyruvic acid?
Pyruvic acid is the simplest of the alpha-keto acids, which are organic compounds containing both a carboxylic acid functional group (-COOH) and a ketone functional group (C=O). It is a key intermediate in many metabolic pathways within living organisms and serves as a crucial link between different biochemical processes.
2. What is the chemical formula and structure of pyruvic acid?
The chemical formula for pyruvic acid is C₃H₄O₃. Its structure consists of a three-carbon backbone. One terminal carbon is part of a carboxylic acid group (COOH), the middle carbon is a ketone group (C=O), and the other terminal carbon is part of a methyl group (CH₃).
3. What is the primary role of pyruvic acid in glycolysis?
In glycolysis, pyruvic acid is the final product. This metabolic pathway breaks down one molecule of glucose into two molecules of pyruvic acid in the cytoplasm of the cell. This process also yields a net gain of ATP and NADH, which are essential energy-carrying molecules.
4. What is the difference between pyruvic acid and pyruvate?
The main difference lies in their chemical state. Pyruvic acid (CH₃COCOOH) is the protonated, neutral molecule. Pyruvate (CH₃COCOO⁻) is the deprotonated conjugate base, or anion, of pyruvic acid. In the physiological pH of a cell (around 7.4), pyruvic acid loses a proton (H⁺) and exists predominantly as pyruvate. Therefore, in a biological context, the terms are often used interchangeably.
5. What are the different metabolic fates of pyruvic acid in the body?
The fate of pyruvic acid depends on the availability of oxygen. The main pathways are:
- Aerobic Respiration: In the presence of oxygen, it is converted to acetyl-CoA, which enters the Krebs cycle for complete oxidation to CO₂ and water, generating large amounts of ATP.
- Lactic Acid Fermentation: In the absence of oxygen (e.g., in muscle cells during intense exercise), it is converted to lactic acid.
- Alcoholic Fermentation: In some microorganisms like yeast, it is converted to ethanol and carbon dioxide under anaerobic conditions.
- Anabolism: It can be used to synthesise the amino acid alanine or be converted back to glucose via gluconeogenesis.
6. How does the presence or absence of oxygen determine which pathway pyruvic acid enters?
Oxygen acts as the final electron acceptor in the electron transport chain, which is necessary for the Krebs cycle to function continuously.
- When oxygen is present, pyruvic acid can be fully oxidized via the Krebs cycle to maximize ATP production.
- When oxygen is absent, the cell must regenerate NAD⁺ from NADH to allow glycolysis to continue. It does this through fermentation, converting pyruvic acid to byproducts like lactic acid or ethanol, which does not require oxygen.
7. Why is pyruvic acid considered a central hub in cellular metabolism?
Pyruvic acid is considered a central hub because it stands at the intersection of several major metabolic pathways. It connects the metabolism of carbohydrates (as the end product of glycolysis), fats (through its conversion to acetyl-CoA, a building block for fatty acids), and proteins (through its interconversion with the amino acid alanine). This central position allows the cell to flexibly manage its energy production and biosynthetic needs.
8. How does pyruvic acid contribute to the production of ATP?
Pyruvic acid itself is not an energy currency like ATP. Instead, it is a crucial precursor for large-scale ATP production under aerobic conditions. Its conversion to acetyl-CoA, and the subsequent oxidation of acetyl-CoA in the Krebs cycle, generates high-energy electron carriers (NADH and FADH₂). These molecules then donate their electrons to the electron transport chain, powering the synthesis of a significant amount of ATP.
