Fig. 3
The CA model of the cellulases interacting with and degrading the cellulose surface. a The footprint of the enzyme is shown in blue and the center of the enzyme is shown in light green. The center of an enzyme is set within a distance of three water or cellobiose units to a randomly chosen point on the cellulosic surface (one of two dark green squares). Enzymes screen for substrate sites in their immediate surrounding (red box). For EG, any cellobiose (brown) of amorphous cellulose is a substrate, whereas for the cellobiohydrolases, only cellobioses lacking a neighbor cellobiose (indicated with a yellow cross) are substrates. b Top view of a CBH molecule in processive motion is shown. The wall in front of the enzyme in moving direction (red rectangle) is checked for structural obstacles (cellobiose molecules). The enzyme is represented against other enzymes as a sphere (blue circle) to calculate collision events. If neither substrate nor enzyme obstacles are present, the cellobiohydrolase moves along the chain, cleaving one cellobiose per 1/k cat time interval