Anaplerotic reactions

From Biocrawler, the free encyclopedia.

- of Greek origin, meaning to "fill up"

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.

Contents

1 Pyruvate to oxaloacetate 2 Aspartate to oxaloacetate 3 Glutamate to α-ketoglutarate 4 From β-oxidation of fatty acids

Pyruvate to oxaloacetate

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

This reaction is catalysed by pyruvate decarboxylase, an enzyme activated by Acetyl-CoA, indicating a lack of oxaloacetate.

Pyruvate can also be converted to L-malate, another intermediate, in a similar way.

Aspartate to oxaloacetate

This is a reversible reaction forming oxaloacetate from aspartate in a transamination reaction.

Glutamate to α-ketoglutarate

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

This reaction is catalysed by glutamate dehydrogenase.

From β-oxidation of fatty acids

When odd-chain fatty acids are oxidised, one molecule of succinyl-CoA is formed per fatty acid.

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