Fig. 6
Dynamics of crystalline cellulose degradation depends on the k off of CBH II. The k off of CBH II is key to explain the dynamics of crystalline cellulose degradation by cellulases as modeled. Shown are time courses of ∆h_max (vertical height difference between the highest point on a cellulose crystallite and the amorphous material surrounding the crystallite) during enzymatic degradation of large (~16 nm height; panels a, b) and small (~8 nm height; panels c, d) nanocrystals analyzed by experiment and simulation. Nanocrystals were modeled with their hydrophobic faces aligned horizontally and with their top face touching the enzyme-accessible surface. The ∆h_max required to expose the crystal’s hydrophobic faces was therefore half the height, which is indicated by the dashed black line. Experimental time courses are shown in green. Simulated time courses of ∆h_max using low and high boundary values of k off are shown in red (0.7 × 10−3·s−1) and blue (0.7 × 10−1·s−1), respectively. Shown in orange and magenta are two simulations using the iteratively “optimized” value of 0.7 × 10−2·s−1 for k off