FIGURE 2.

Three-dimensional rendering of time lapse AFM amplitude images of an individual isolated Valonia cellulose crystal in acetate buffer (A) and at 171, 179, 188, 196, 205, 214, and 222 min after addition of CBH I enzyme (B–H). Features observed attached to one side of the cellulose crystal are believed to be CBH I enzyme molecules. Features observed attached to one side of the cellulose crystal are believed to be CBH I enzyme molecules. Features appearing to have two different sizes may represent the two modules of CBH I (i.e. CD and CBM indicated by solid and open arrows, respectively). The location of CBH I on cellulose was shown to change, which indicates movement of the enzyme. The measured relative position of putative CDs and CBMs was also observed to change between ∼5–10 nm, which is consistent with the modeled linker length, indicating that CBH I may be a dynamic structure during the catalytic process. Scale bar, 10 nm.