Performed In-gel assays using nondenaturing SDS polyacrylamide gel electrophoresis (SDS-PAGE) for visualizing pectinase and cellulase activities.
Diluted Enzyme extractwas in electrophoresis sample buffer containing 25% stacking buffer (0.5M Tris–HCl; pH6.8), 20% glycerol, 2% SDS, and 0.005% (w/v) bromophenol blue.
Denatured The cellulase sample partially at 70 °C for 20min to increase electrophoresis resolution.
Centrifuged following heating, the samples briefly (Oppert et al., 2009) and then loaded on a 5% stacking and 10% separating polyacrylamide gel.
Incorporated the substrate pectin and CMC into the separating gels at a final concentration of
1% and 0.1% for detecting pectinase and cellulase, respectively.
Washed after electrophoresis, the gels in citrate buffer (pH 6) containing 2.5% (v/v) Triton X-100 for 45min and then incubated in citrate buffer (pH 6) with gentle agitation for 60min for pectinase and 2 h for cellulase.
Stained the gels for visualizing pectinase with Ruthenium red (0.03%), and the bands of pectinase activity appeared as clear areas in a red gel background.
Stained In the case of cellulase, the gels with Congo red (0.1%) for 10–15min at room temperature.
Destained the gels by washing in 50mL 1 M NaCl until the cellulose bands became obvious as clear zones where the CMC had been degraded due to enzymatic activity.
Added after 20min of destaining, 100 μLofglacial acetic acid to the gel for better visualization (Waeonukul etal., 2007).
Estimated the kinetic parameters of themidgut pectinase at pH 6 and 45 °C. The KM and Vmax values for the enzyme were 2 mg•mL−1 and 0.017 mmol•min−1•mg−1 protein, respectively.
Showed Zymogram analyses at least one pectinase activity band (125 kDa) in the larval midgut by PAGE .