Anaplerotic reactions are those that form intermediates of the TCA or citric acid cycle. As this is a cycle, formation of any of the intermediates can be used to 'top up' the whole cycle. Anaplerotic is of Greek origin, meaning "to fill up". The citric acid cycle (also known as the tricarboxylic acid cycle, the TCA cycle, or the Krebs cycle) is a series of chemical reactions of central importance in all living cells that utilize oxygen as part of cellular respiration. ... A cycle (Latin cyclus, from Greek kuklos meaning circle) is anything round, in the physical sense (e. ...

There are 4 reactions classed as anaplerotic, although the production of oxaloacetate from pyruvate is probably the most important physiologically.

Pyruvate to oxaloacetate

pyruvate + CO₂ + H₂O + ATP oxaloacetate + ADP + Pi + 2H⁺

This reaction is catalysed by pyruvate carboxylase, an enzyme activated by Acetyl-CoA, indicating a lack of oxaloacetate. Ribbon diagram of the catalytically perfect enzyme TIM. An enzyme is a protein that catalyzes, or speeds up, a chemical reaction. ... Categories: Biochemistry stubs | Thiols ...

Pyruvate can also be converted to L-malate, another intermediate, in a similar way. Pyruvate (CH3COCOO−) is the ionized form of pyruvic acid. ... Malic acid is a tart-tasting organic acid that plays a role in many sour or tart foods. ...

Aspartate to oxaloacetate

This is a reversible reaction forming oxaloacetate from aspartate in a transamination reaction. Aspartic acid, also known as aspartate, the name of its anion, is one of the 20 natural proteinogenic amino acids which are the building blocks of proteins. ... Transamination is the reaction between an amino acid and an alpha-keto acid. ...

Glutamate to α-ketoglutarate

glutamate + NAD⁺ + H₂O NH₄⁺ + α-ketoglutarate + NADH + H⁺

This reaction is catalysed by glutamate-dehydrogenase. Glutamate is the anion of glutamic acid. ...

β-oxidation of fatty acids to succinyl-CoA

When odd-chain fatty acids are oxidised, one molecule of succinyl-CoA is formed per fatty acid. In chemistry, especially biochemistry, a fatty acid is a carboxylic acid (or organic acid), often with a long aliphatic tail (long chains), either saturated or unsaturated. ...