Expression and Characterization of a Novel β-Porphyranase from Marine Bacterium Wenyingzhuangia fucanilytica: A Biotechnological Tool for Degrading Porphyran.

Porphyra is one of the most consumed types of red algae. Porphyran is the major polysaccharide extracted from Porphyra, and it is composed of alternating 4-linked α-l-galactopyranose-6-sulfate (L6S) and 3-linked β-d-galactopyranose (G) residues. β-Porphyranases are promising tools for degrading porphyran; however, few enzymes have been reported, and the biochemical properties of porphyranases are still unclear. Here, a novel GH16 β-porphyranase, designated as Por16A_Wf, was cloned from Wenyingzhuangia fucanilytica and expressed in Escherichia coli. Its biochemical properties and hydrolysis pattern were characterized. Por16A_Wf exhibited stable activity on a wide pH scale from 3.5 to 11.0. Glycomics analysis using LC-MS revealed that Por16A_Wf specifically hydrolyzed the glycosidic linkage of G-L6S, whereas it tolerated 3,6-anhydro-α-l-galactopyranose and methyl-d-galactose in -2 and +2 subsites, respectively. Por16A_Wf could be applied as a biotechnological tool for tailoring porphyran, which would serve in directional preparation of its disaccharide, producing products with various molecular weights and facilitating investigation of the structural heterogeneity of Porphyra polysaccharides.