Activity assay on CMC, PASC, and xylan
Cel9B truncation mutants were assayed for their relative enzyme
activities on various substrates. Release of glucose (in terms of
reducing sugars) from each substrate was quantitated with increasing
concentrations of enzyme for wild type and truncation mutants of Cel9B.
Mutant cd9B, consisting of only the catalytic domain, had the highest
activity on CMC, followed by mutant M1 (containing CBM4), M2 (containing
CBM2), and then wild type Cel9B. Other truncation mutants exhibited
activity that was lower than that of Cel9B (Figure 2). Conversely, when
PASC was used as a substrate, Cel9B and mutants M1 and M2 exhibited
similar activities that were greater than cd9B (Figure 3). All other
truncation mutants exhibited activities that were similar to cd9B, with
mutant ΔFn3 displaying the lowest activity (Figure 4). A similar
activity profile to that found for PASC was found for Cel9B and the
truncation mutants when xylan was used as a substrate.