Chapter 3.1 - Plant and Microbial Enzymes Involved in the Depolymerization of (1,3)-β-d-Glucans and Related Polysaccharides

Abstract

This chapter summarizes the major classes of enzymes that are responsible for the depolymerization of (1,3)-β-d-glucans and related polysaccharides, with an emphasis on the enzymes found in higher plants. Although (1,3)-β-d-glucans are generally linear homopolymers of (1,3)-linked β-d-glucopyranosyl residues, structural variants of linear (1,3)-β-d-glucans include cyclic (1,3;1,6)-β-d-glucans, branch-on-branch (1,3;1,6)-β-d-glucans, side-chain-branched (1,3;1,6)-β-d-glucans, (1,3;1,6)- β -d-glucans with both (1,3)- and (1,6)-linkages in the main chain, and side-chain-branched (1,3;1,2)-β-d-glucans This chapter discusses major classes of enzymes, and in some cases closely related enzymes. Enzymes that catalyze the hydrolysis of (1,3)-β-d-glucans with an endo-action pattern have traditionally been classified in the EC 3.2.1.39 group, although representatives of this group have been classified according to their structural features in families GH16, GH17, GH55, GH64, and GH81 of the CAZY database.