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[Biochemistry](https://durgical.com/en/biochemistry/) · Molecule

# Alanine

Alanine carries nitrogen from muscle to the liver, where it becomes pyruvate again to make glucose (glucose–alanine cycle).

Updated 2026-11-01

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## Key facts

- ALT swaps alanine + α-ketoglutarate for pyruvate + glutamate.
- It is the main glucogenic amino acid released by muscle during fasting.
- Glucose–alanine cycle: muscle exports alanine; the liver uses the pyruvate for gluconeogenesis and the amino group for urea.
- Non-essential; its carbon skeleton is pyruvate.

**Formula**
C₃H₇NO₂

**PubChem**
[CID 5950](https://pubchem.ncbi.nlm.nih.gov/compound/5950)

## Structure

- The simplest chiral amino acid: a methyl side chain; it is pyruvate with an amino group in place of the carbonyl.

## Clinical notes

- It rises in blood in lactic acidosis and pyruvate dehydrogenase deficiency, because piled-up pyruvate is transaminated.
- The enzyme that transaminates it, ALT, is the most specific marker of liver damage.

## Related conditions

- [Lactic acidosis](https://durgical.com/en/conditions/lactic-acidosis/)
- [Pyruvate dehydrogenase deficiency](https://durgical.com/en/conditions/pyruvate-dehydrogenase-deficiency/)

## Related

- [Pyruvate](https://durgical.com/en/biochemistry/molecules/pyruvate/)
- [Alanine aminotransferase (ALT, GPT)](https://durgical.com/en/biochemistry/enzymes/alanine-aminotransferase/)
- [Glutamate (glutamic acid)](https://durgical.com/en/biochemistry/molecules/glutamate/)
- [Transamination and deamination](https://durgical.com/en/biochemistry/topics/transamination-and-deamination/)
- [Glucogenic and ketogenic amino acids](https://durgical.com/en/biochemistry/topics/glucogenic-and-ketogenic-amino-acids/)

## Test yourself

Think of the answer, then tap the question to see it.

## Which keto acid forms when alanine loses its amino group?

Pyruvate, which the liver can use to make glucose.

## What does the glucose–alanine cycle do for muscle?

It lets muscle send the nitrogen of its amino acids to the liver without releasing ammonia, and get glucose back.

## Why does alanine rise in pyruvate dehydrogenase deficiency?

Pyruvate cannot enter the Krebs cycle, piles up, and part of it is transaminated to alanine.

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Molecules are shown in their neutral form, as the databases deposit them; in the cell the acids and phosphates are ionised.

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [L-Alanine (CID 5950)](https://pubchem.ncbi.nlm.nih.gov/compound/5950) (PubChem, NCBI, 2026) · Public domain; [Metabolism of amino acids and derivatives](https://reactome.org/PathwayBrowser/#/R-HSA-71291) (Reactome, 2026); Textbook of Biochemistry for Medical Students, 6th ed. (Jaypee Brothers Medical Publishers (Vasudevan DM, Sreekumari S, Vaidyanathan K), 2011).

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