1GHS

Two plant beta-glucan endohydrolases with distinct substrate specificities, thought to have evolved from the same higher enzyme, which both hydrolyse 1,3-beta-D-glucosidic linkages in 1,3-beta-D-glucans. Chain A is the isoenzyme GII, (1->3)-beta-glucanase with EC:3.2.1.39 and chain B is the isoenzyme EII (1->3, 1->4)- beta glucanase with EC:3.2.1.73. Isoenzyme GII can hydrolyse beta-glucans of fungal cell walls and may therefore contribute to plant defence strategies, whereas isoenzyme GII function in plant cell wall hydrolysis during mobilisation of the endosperm or in germinating grain during the growth of vegetative tissue. Both glucanases have essentially identical alpha/beta barrel folds, with a recognisable cleft where the active site is located in the same position with identical catalytic residues, however beyond the conserved patch that surrounds the catalytic amino acid residues, there are different amino acid substitutions along the substrate-binding cleft leading to different substrate specificities. This protein is a member of glycoside hydrolase family 17.