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A new class EC 7, Translocases, has been added to the EC list. It will be part of ENZYME from release 2018_10. Read more about EC 7 here.

ENZYME entry: EC 4.2.2.19

Accepted Name

Chondroitin B lyase.

Alternative Name(s)

ChonB.

Chondroitinase B.

Reaction catalysed

Eliminative cleavage of dermatan sulfate containing (1->4)-beta-D-hexosaminyl and (1->3)-beta-D-glucurosonyl or (1->3)-alpha-L-iduronosyl linkages to disaccharides containing 4-deoxy-beta-D-gluc-4-enuronosyl groups to yield a 4,5-unsaturated dermatan-sulfate disaccharide (Delta-UA-GalNAc-4S)

Comment(s)

This is the only lyase that is known to be specific for dermatan sulfate as substrate.
The minimum substrate length required for catalysis is a tetrasaccharide.
In general, chondroitin sulfate (CS) and dermatan sulfate (DS) chains comprise a linkage region, a chain cap and a repeat region.
The repeat region of CS is a repeating disaccharide of glucuronic acid (GlcA) and N-acetylgalactosamine (GalNAc) [-4)GlcA(beta-1- 3)GalNAc(beta-1-](n), which may be O-sulfated on the C-4 and/or C-6 of GalNAc and C-2 of GlcA.
GlcA residues of CS may be epimerized to iduronic acid (IdoA) forming the repeating disaccharide [-4)IdoA(alpha-1-3)GalNAc(beta-1-](n) of DS.
Both the concentrations and locations of sulfate-ester substituents vary with glucosaminoglycan source.

Cross-references

BRENDA

4.2.2.19

EC2PDB

4.2.2.19

ExplorEnz

4.2.2.19

PRIAM enzyme-specific profiles

4.2.2.19

KEGG Ligand Database for Enzyme Nomenclature

4.2.2.19

IUBMB Enzyme Nomenclature