Results
Cel9B truncation mutants were designed in such a way that five different
structural domains (identified in the CAZy website;
(http://www.cazy.org/) Lombard et
al., 2013) were either removed or retained with the objective of
elucidating their specific function (Figure 1, Table 2). All the
truncation mutants contained a His tag so that they could be easily
purified on a nickel column. Although each of the seven mutants tested
exhibited activity on CMC, it was observed that mutant Fn3, which
retained the fibronectin-like domain located within the protein, had a
reduced capacity to bind to the nickel column. This suggested that the
protein structure had been altered so that the 6His tag was no longer
available to bind to the column. In addition to this, the truncation
mutant ΔFn39B grew poorly.