KEGG   ENZYME: 3.2.1.178Help
Entry
EC 3.2.1.178                Enzyme                                 

Name
beta-porphyranase;
porphyranase;
PorA;
PorB;
endo-beta-porphyranase
Class
Hydrolases;
Glycosylases;
Glycosidases, i.e. enzymes that hydrolyse O- and S-glycosyl compounds
BRITE hierarchy
Sysname
porphyran beta-D-galactopyranose-(1->4)-alpha-L-galactopyranose-6-sulfate 4-glycanohydrolase
Reaction(IUBMB)
Hydrolysis of beta-D-galactopyranose-(1->4)-alpha-L-galactopyranose-6-sulfate linkages in porphyran
Comment
The backbone of porphyran consists largely (~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] [2]. 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 [1]. Methylation of the D-galactose prevents its binding at position -1 [2].
History
EC 3.2.1.178 created 2011
Reference
1  [PMID:20376150]
  Authors
Hehemann JH, Correc G, Barbeyron T, Helbert W, Czjzek M, Michel G
  Title
Transfer of carbohydrate-active enzymes from marine bacteria to Japanese gut microbiota.
  Journal
Nature. 464 (2010) 908-12.
  Sequence
Reference
2
  Authors
Correc, G., Hehemann, J.H., Czjzek, M. and Helbert, W.
  Title
Structural analysis of the degradation products of porphyran digested by Zobellia galactanivorans beta-porphyranase A.
  Journal
Carbohydrate Polymers 83 (2011) 277-283.
Other DBs
ExplorEnz - The Enzyme Database: 
IUBMB Enzyme Nomenclature: 
ExPASy - ENZYME nomenclature database: 
BRENDA, the Enzyme Database: 

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