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 the enzyme from Zobellia galactanivorans, but not that from Wenyingzhuangia fucanilytica, from binding at subsite -1 [2,3].
