The enzyme endoglucanase from Acidothermus cellulolyticus, belonging to CAZy GH5 family (pdb id: 1ece) is shown in cartoon representation. The active site is highlighted with the substrate binding residues that form a hydrogen bond (colored yellow). The two catalytic residues Glu162 and Glu282 are colored separately. Glu282, the nucleophile, is shown in stick representation and colored red, and Glu162, the acid-base donor, is shown in stick representation and colored dark blue.