A Role of Cellulose Binding Module of the Thermophilic Endoglucanase TbCel12A

Abstract

Endoglucanases are enzymes that play an important role in hydrolysis of lignocellulose by attacking glycosidic linkages in cellulose fibers and other glucans. The cellulose binding module (CBM) is responsible for binding the enzyme to the substrate. However, CBMs in certain enzymes interfere with substrate hydrolysis resulting in moderate or low activity. In a previous study, the processive endoglucanase TbCel12A including its CBM had low activity towards carboxymethyl cellulose (CMC). To assess the effect of the CBM, the catalytic domain of TbCel12A was produced without the CBM. The TbCel12A catalytic domain without the CBM hydrolyzed CMC 23 times more rapidly, while the pH and temperature optima and thermotolerance remained unchanged compared to full-length TbCel12A. Therefore, TbCel12A does not require the CBM for CMC hydrolysis and its application may be improved without it.