ENZYME

ENZYME entry: EC 3.2.1.178

Accepted Name

Beta-porphyranase.

Alternative Name(s)

Endo-beta-porphyranase.

Porphyranase.

Reaction catalysed

Hydrolysis of beta-D-galactopyranose-(1->4)-alpha-L-galactopyranose-6-sulfate linkages in porphyran

Comment(s)

The backbone of porphyran consists largely (approximately 70%) of (1->3)-linked beta-D-galactopyranose followed by (1->4)-linked alpha- L-galactopyranose-6-sulfate (the other 30% are mostly agarobiose repeating units of (1->3)-linked beta-D-galactopyranose followed by (1->4)-linked 3,6-anhydro-alpha-L-galactopyranose).
This enzyme cleaves the (1->4) linkages between beta-D- galactopyranose and alpha-L-galactopyranose-6-sulfate, forming mostly the disaccharide alpha-L-galactopyranose-6-sulfate-(1->3)-beta-D- galactose, although some longer oligosaccharides of even number of residues are also observed.
Since the enzyme is inactive on the non-sulfated agarose portion of the porphyran backbone, some agarose fragments are also included in the products.
Methylation of the D-galactose prevents its binding at position -1.

Cross-references

BRENDA

EC2PDB

ExplorEnz

PRIAM enzyme-specific profiles

KEGG Ligand Database for Enzyme Nomenclature

IUBMB Enzyme Nomenclature