Figure 39.

Unidirectional processive run of cellulase on crystalline cellulose fiber captured by HS-AFM. (a) Schematic of cellulase (cellobiohydrolase: CBH) with two-domain structure attached onto the surface of crystalline cellulose. (b) Clips of successive AFM images showing processive and unidirectional movement of TrCel7A on crystalline cellulose I_α. Imaging rate, 3.3 fps. Two molecules are marked with the arrows with different colors. (c) Intermittent “go and stop” movement of TrCel7A molecules on cellulose I_α. The movements of seven molecules are shown with the marks with different colors. (d) Velocity distribution of the linear movement of TrCel7A on crystalline cellulose I_α (n = 188). The histogram was approximated by the combination of two Gaussian distribution curves (blue line) with mean ± SD values of −0.32 ± 3.4 (red) and 7.1 ± 3.9 nm/s (green). (e) Successive AFM images showing traffic jam of TrCel7A bound to crystalline cellulose I_α. Imaging rate, 3.3 fps. The congestion is marked with the arrows.