In the case of cellulases, where this type of domain was firstdiscovered, the domain was originally called a cellulosebinding domain and then the name was changed to carbohydrate binding module (CBM), so as to include the manyother types of polysaccharide binding domains. It is clearthat one role of the CBM is to bind the enzyme to thecellulose so that the cd spends less time away from thesubstrate and it also gives the cd time to move the chaininto its active site before the enzyme diffuses away fromthe cellulose particle. It is still not clear whether the CBMalso can modify cellulose or otherwise assist cellulosehydrolysis by the catalytic domain