[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Biochemistry](https://durgical.com/en/biochemistry/) › Glycogen debranching enzyme

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

# Glycogen debranching enzyme

The debranching enzyme removes glycogen's branches so phosphorylase can keep going; it has two activities in a single protein.

Updated 2026-11-01

Loading the 3D model…

## Key facts

- Transferase activity (4-α-glucanotransferase): it moves a block of 3 glucose units from the branch to another chain.
- Glucosidase activity (amylo-α-1,6-glucosidase): it hydrolyses the last α-1,6-linked glucose and frees it as free glucose.
- A single polypeptide chain encoded by the AGL gene.
- Structure 8ZEQ (cryo-EM, human) has no bound ligand: the whole protein is shown.

**EC number**
[2.4.1.25, 3.2.1.33](https://www.enzyme-database.org/query.php?ec=2.4.1.25, 3.2.1.33)

**Genes**
AGL

**Structure (PDB)**
[8ZEQ](https://www.rcsb.org/structure/8ZEQ)

## Regulation

- No direct hormonal regulation is known: it works at the pace set by phosphorylase.

## Inhibitors and toxins

- No clinically used inhibitors

## Clinical notes

- Its deficiency is Cori disease (GSD III): limit dextrin with short branches accumulates; hepatomegaly, hypoglycaemia and, in type IIIa, myopathy and cardiomyopathy.
- Unlike GSD I, in GSD III lactate and uric acid are usually normal because gluconeogenesis works.

## Pathways

- [Glycogen metabolism](https://durgical.com/en/biochemistry/pathways/glycogen-metabolism/)

## Related conditions

- [Cori disease (glycogen storage disease type III)](https://durgical.com/en/conditions/cori-disease/)

## Related

- [Glycogen](https://durgical.com/en/biochemistry/molecules/glycogen/)
- [Glycogen phosphorylase](https://durgical.com/en/biochemistry/enzymes/glycogen-phosphorylase/)
- [Glycogen synthase](https://durgical.com/en/biochemistry/enzymes/glycogen-synthase/)

## Test yourself

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

## What are the two activities of the debranching enzyme?

Transferase (moves 3 glucose units to another chain) and α-1,6-glucosidase (frees the glucose at the branch point).

## What accumulates in Cori disease?

Glycogen with short outer branches (limit dextrin), because phosphorylase cannot get past the branches.

## Why is lactate normal in GSD III but not in GSD I?

In GSD III glucose-6-phosphatase works and gluconeogenesis continues; in GSD I that final step is blocked.

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

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

Sources: [AGL: Glycogen debranching enzyme (human)](https://www.uniprot.org/uniprotkb/P35573/entry) (UniProt, 2026); [AGL gene: MedlinePlus Genetics](https://medlineplus.gov/genetics/gene/agl/) (MedlinePlus, US National Library of Medicine, 2026); [8ZEQ: Molecular Architecture of Human Glycogen Debranching Enzyme: Insights into Glycogen Storage Disease III Pathogenesis](https://www.rcsb.org/structure/8ZEQ) (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/glycogen-debranching-enzyme/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/biochemistry/enzymes/glycogen-debranching-enzyme/