Function of carbohydrate binding modules

What is the origin of substrate recognition by enzymes?
Carbohydrate Binding Modules play important roles in substrate-enzyme interaction, and some CBMs bind to crystalline surfaces and others do amorphous chains. Such behavior can be visually inspected by TEM observation.

Lehtio J, Sugiyama J, Gustavsson M, Fransson L, Teeri TT: The binding specificity and affinity determinants of the family 1 cellulose-binding domains from Trichoderma reesei Cel6A and Cel7A. Proc Natl Acad Sci USA, 100, 484-489, 2003