2.8.1. Endocellulase production
Carboxymethyl cellulose (CMC) was used as substrate to determine
endocellulase activity. Samples were incubated with 2.0% (w/
V) CMC in 50 mM acetate buffer pH 5.0 at 50 C for 60 min.
Reducing sugars released during the reaction were determined as
described in Section 2.7.2. Glucose was used as standard. One unit
(U mL1) of endocellulase activity was defined as the amount of
enzyme required to produce 1 mmol of glucose in 1 min at 50 C.
Specific endocellulase activity (U mg1) was expressed as 1 U per
1 mg of protein present in the FE.
Proteins in the FE were separated by isoelectric focusing (IEF)
using the Multiphor II electrophoresis system (Pharmacia-LKB
Biotechnology) according to the manufacturer's instructions.
Focusing was carried out on a 6% polyacrylamide gel with
ampholytes in the 3e10 pH range. Endocellulase isoforms were
detected in acrylamide (AA) (7.5%) gel with copolymerized 1% CMC,
previously printed from IEF gel for 55 min. The cellulase zymogram was further prepared as previously described by Pavlovic et al.
(2012