Structure of β‐1,4‐mannanase from the common sea hare
Abstract:β‐1,4‐Mannanase (EC 18.104.22.168) catalyzes the hydrolysis of β‐1,4‐glycosidic bonds within mannan, a major constituent group of the hemicelluloses. Bivalves and gastropods possess β‐1,4‐mannanase and may degrade mannan in seaweed and/or phytoplankton to obtain carbon and energy using the secreted enzymes in their digestive systems. In the present study, the crystal structure of AkMan, a gastropod β‐1,4‐mannanase prepared from the common sea hare Aplysia kurodai, was determined at 1.05 Å resolution. This is the first report of the three‐dimensional structure of a gastropod β‐1,4‐mannanase. The structure was compared with bivalve β‐1,4‐mannanase and the roles of residues in the catalytic cleft were investigated. No obvious binding residue was found in subsite +1 and the substrate‐binding site was exposed to the molecular surface, which may account for the enzymatic properties of mannanases that can digest complex substrates such as glucomannan and branched mannan.
Document Type: Research Article
Publication date: October 1, 2012