Trichoderma reesei produces 2 processive cellobiohydrolases, CBHI and CBHII.  The former is specific to the reducing-end of cellulose whereas the latter is a nonreducing-end specific enzyme.  It is known that these enzymes act in concert when degrading crystalline cellulose, and therefore increase the rate of conversion when used simultaneously in an enzyme cocktail.  Both enzymes consist of a carbohydrate-binding module [CBM] and a large catalytic domain connected by O-glycosylated linker peptides.  We use molecular simulation techniques to investigate the binding and action of these CBMs on a crystalline cellulose substrate.  The results from these simulations aid in understanding the specificity of these CBMs and their roles in processivity.  Where possible, we use these computational results in concert with traditional experimental biochemistry to understand the function of each enzyme sub-domain.