Effect of SDS and proteinase K on the BSX and R-BSX.

<p>(A) and (B) show SDS-PAGE profiles for determining the SDS-stability of proteins. Identical protein samples were loaded onto the gel with or without prior boiling for 10 min, respectively. (C) Xylanase activity in the presence of SDS. Samples were incubated for 12 h in the presence of various concentrations of SDS prior to the activity assay. Note that V1F and V1D displayed maximum activity. (D) Thermostability of xylanase and its mutants. Samples were incubated for 15 min at various temperatures and assayed for residual xylanase activity at their respective optimum temperature (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0003063#s4" target="_blank">material and methods</a>). (E) Alkaline stability of BSX, R-BSX and its mutants. Note the drastic reduction in the activity of the V1G mutant when the enzyme was incubated above pH 10 prior to the assay.