beta-porphyranase A, BpGH16B, BpGH86A, endo-beta-porphyranase, PORA, PORB, porphyranase
EC Number
3.2.1.178
CAS Registry Number
Comments
The backbone of porphyran consists largely (~70%) of (1¡ú3)-linked ¦Â-D-galactopyranose followed by (1¡ú4)-linked ¦Á-L-galactopyranose-6-sulfate [the other 30% are mostly agarobiose repeating units of (1¡ú3)-linked ¦Â-D-galactopyranose followed by (1¡ú4)-linked 3,6-anhydro-¦Á-L-galactopyranose] [2]. This enzyme cleaves the (1¡ú4) linkages between ¦Â-D-galactopyranose and ¦Á-L-galactopyranose-6-sulfate, forming mostly the disaccharide ¦Á-L-galactopyranose-6-sulfate-(1¡ú3)-¦Â-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].
Cofactor
History
Reactions
Hydrolysis of beta-D-galactopyranose-(1->4)-alpha-L-galactopyranose-6- sulfate linkages in porphyran.
