[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Biochemistry](https://durgical.com/en/biochemistry/) › Aldolase B

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

# Aldolase B

Liver aldolase B splits fructose 1-phosphate into two trioses; if it is missing, dietary fructose becomes toxic.

Updated 2026-11-01

Loading the 3D model…

## Key facts

- Fructose 1-phosphate → DHAP + glyceraldehyde; it also splits fructose 1,6-bisphosphate (glycolysis and gluconeogenesis).
- Isoenzymes: A (muscle and red cell), B (liver, kidney, intestine) and C (brain); only B handles fructose 1-phosphate well.
- It uses an active-site lysine that forms a Schiff base with the substrate (class I aldolase).
- Structure 1QO5 (human liver) has only sulfate ions in the active site, where the substrate phosphates sit.

**EC number**
[4.1.2.13](https://www.enzyme-database.org/query.php?ec=4.1.2.13)

**Genes**
ALDOB

**Structure (PDB)**
[1QO5](https://www.rcsb.org/structure/1QO5)

## Regulation

- It is induced by a diet rich in carbohydrate and fructose; insulin increases its liver expression.

## Inhibitors and toxins

- Fructose 1-phosphate accumulated in its defective variants

## Clinical notes

- Its deficiency is hereditary fructose intolerance: hypoglycaemia, vomiting and liver and kidney damage after fructose, sucrose or sorbitol.
- The most common variant in people of European descent is A149P.

## Pathways

- [Fructose metabolism](https://durgical.com/en/biochemistry/pathways/fructose-metabolism/)
- [Glycolysis](https://durgical.com/en/biochemistry/pathways/glycolysis/)

## Related conditions

- [Hereditary fructose intolerance](https://durgical.com/en/conditions/hereditary-fructose-intolerance/)

## Related

- [Fructose](https://durgical.com/en/biochemistry/molecules/fructose/)
- [Fructose 1,6-bisphosphate](https://durgical.com/en/biochemistry/molecules/fructose-1-6-bisphosphate/)
- [Glucose](https://durgical.com/en/biochemistry/molecules/glucose/)

## Test yourself

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

## Which substrate sets aldolase B apart from aldolase A?

Fructose 1-phosphate: B splits it well; A hardly at all.

## Why does aldolase B deficiency cause hypoglycaemia?

Accumulated fructose 1-phosphate traps phosphate and blocks glycogen phosphorylase and gluconeogenesis.

## In which organs is aldolase B expressed?

Liver, renal cortex and small intestine.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/biochemistry/enzymes/aldolase-b/)

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

Sources: [ALDOB: Fructose-bisphosphate aldolase B (human)](https://www.uniprot.org/uniprotkb/P05062/entry) (UniProt, 2026); [ALDOB gene: MedlinePlus Genetics](https://medlineplus.gov/genetics/gene/aldob/) (MedlinePlus, US National Library of Medicine, 2026); [1QO5: Fructose 1,6-bisphosphate Aldolase from Human Liver Tissue](https://www.rcsb.org/structure/1QO5) (RCSB Protein Data Bank, 2026); Textbook of Biochemistry for Medical Students, 6th ed. (Jaypee Brothers Medical Publishers (Vasudevan DM, Sreekumari S, Vaidyanathan K), 2011).

[← All of biochemistry](https://durgical.com/en/biochemistry/)

## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake

Representative model, for educational purposes only.

---
Source: https://durgical.com/en/biochemistry/enzymes/aldolase-b/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/biochemistry/enzymes/aldolase-b/