Xylanase enzyme isolated from the fungi Thermomyces lanuginosus was found to be very temperature stable. Using the Synergy™ H4 to incubate assay plates from 25° - 65° C, xylanase activity was measured after a 15 minute incubation. Enzyme concentration titration curves indicate that higher temperatures result in slightly more hydrolysis than ambient temperatures (Figure 7). Despite incubation at 65° C, enzyme activity demonstrated a 6.5% increase in signal as compared to activity incubated at 25° C.
The effect of pH levels on Thermomyces lanuginosus xylanase activity was tested from a pH of 5.0 to 9.5. As demonstrated in Figure 8, the enzyme works best in an acidic pH. Enzyme reactions (100 mU/mL) carried out at a pH of 9.5 had less than 25% of the fluorescence of reactions at a pH of 5.0 after 30 minute incubation.
Note that the effect of pH on the fluorescence of the reacted substrate must be accounted for when comparing results at different pH levels. In these experiments, equivalent concentrations of a reference standard were used to normalize data prior to plotting.