2.8.3. Xylanase production
Xylanase activity was determined using 1% xylan solution in 50 mM acetate buffer pH 5.0, as substrate. The reaction was carried out for 15 min at 50 C. Reducing sugars released during the reaction were determined as described in Section 2.7.2. Xylose was used as standard. One unit of xylanase activity was defined as the amount of enzyme required to produce 1 mmol of xylose per 1 min at 50 C. Specific xylanase activity (U mg1) was presented as
1 U per 1 mg of proteinpresent in the FE. Xylanase isoforms were detected after incubation of the IEF gel in 1% xylan solution in 50 mMacetate buffer pH 5.0 for 1 h at 37 C. IEF was performed as described in section 2.8.1. The gel was coloured with 0.1% Congo red, and thenwashed in 1 M NaCl. Xylanase isoforms were detected on red gel as illuminated bands. Prior to scanning, the gel was rinsed in acetic acid for 3 min resulting in change of background colour from red to blue-violet.