Synergism between corn stover protein and cellulase

A cellulase synergistic protein named Zea h was purified from fresh postharvest corn stover through sequential treatments. The purified Zea h was homogeneous by PAGE and SDS-PAGE examination, indicating its purity and molecular weight (Mw) of approximately 55.78 kDa. Comparing with cellulase (0.042 FPU) was applied alone in hydrolysis of filter paper, when Zea h (6 μg) and cellulase were applied together, the hydrolysis rate was increased by a factor of 2 within 1 h, and the total cellulose conversion was increased by a factor of 3 during the 24 hʹs hydrolysis. Thermal stability analysis revealed that 50.2% of the synergetic activity was recovered when Zea h was incubated in water for 30 min at 100 °C, yet the protein was deactivated in high pressure steam (160 °C) for 5 min. Studies on the mechanisms of the synergism between Zea h and cellulase showed that, Zea h could increase the adsorption of cellulase onto substrate, and decrease the hydrogen-bond intensity and CrI of substrate. Yet Zea h has no cellulase activity, and has little effect on cellulase stability under the conditions of hydrolysis. It could be concluded that Zea h may modify the structure of filter paper through weakening or rupturing hydrogen bonds, and more it more accessible to cellulase. The unique property of Zea h provides an opportunity for decreasing enzyme loading while retaining the same degree of hydrolysis.