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 (M,,) of approximately 55.78 kDa. Comparing with cellulase (0.042 FPU) was applied alone in hydrolysis of filter paper, when Zea h (6 mu g) 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 It's 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 degrees C, yet the protein was deactivated in high pressure steam (160 degrees 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 It has no cellulase activity, and has little effect on cellulase stability under the conditions of hydrolysis. It could be concluded that Zea It 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 It provides an opportunity for decreasing enzyme loading while retaining the same degree of hydrolysis. (C) 2007 Elsevier Inc. All rights reserved.