Cloning, expression and characterization of a ι-carrageenase from marine bacterium Wenyingzhuangia fucanilytica: A biocatalyst for producing ι-carrageenan oligosaccharides.

ι-Carrageenan is an algal polysaccharide widely applied in the food industry. Specific glycoside hydrolases are valuable tools for modifying polysaccharides and producing oligosaccharides. In this study, the gene of a novel GH82 family ι-carrageenase was cloned from the genome of marine bacterium Wenyingzhuangia fucanilytica . The ι-carrageenase designated as Cgi82A was expressed in Escherichia coli , and its biochemical properties, kinetic constants and hydrolysis pattern were characterized. The enzyme could reach its highest activity at 25 °C, which is lower than all hitherto reported GH82 ι-carrageenases. It was an endo-acting hydrolase, and could be utilized as a potential biocatalyst for producing ι-carrageenan oligosaccharides with different polymerization degrees. Cgi82A possessed relatively high substrate-binding affinity and catalysis efficiency indicated by its kinetic constants ( K m , 1.12 μM; K cat , 560.75 s −1 ). Its major end product was ι-carrageenan tetrasaccharide. The acquiring of this novel enzyme would facilitate the future application of ι-carrageenan and its oligosaccharides. [ABSTRACT FROM AUTHOR]