Neutron Reflectometry and QCM-D Study of the Interaction of Cellulase Enzymes with Films of Amorphous Cellulose
- ORNL
- Sandia National Laboratories (SNL)
- Joint Bioenergy Institute
- Virginia Polytechnic Institute and State University (Virginia Tech)
- Los Alamos National Laboratory (LANL)
- NIST Center for Neutron Research (NCRN), Gaithersburg, MD
Improving the efficiency of enzymatic hydrolysis of cellulose is one of the key technological hurdles to reduce the cost of producing ethanol and other transportation fuels from lignocellulosic material. A better understanding of how soluble enzymes interact with insoluble cellulose will aid in the design of more efficient enzyme systems. We report a study involving neutron reflectometry (NR) and quartz crystal microbalance with dissipation (QCM-D) of the interaction of a commercial fungal enzyme extract (T. viride), two purified endoglucanses from thermophilic bacteria (Cel9A from A. acidocaldarius and Cel5A from T. maritima), and a mesophilic fungal endoglucanase (Cel45A from H. insolens) with amorphous cellulose films. The use of amorphous cellulose is motivated by the promise of ionic liquid pretreatment as a second generation technology that disrupts the native crystalline structure of cellulose. NR reveals the profile of water through the film at nm resolution, while QCM-D provides changes in mass and film stiffness. At 20 oC and 0.3 mg/ml, the T. viride cocktail rapidly digested the entire film, beginning from the surface followed by activity throughout the bulk of the film. For similar conditions, Cel9A and Cel5A were active for only a short period of time and only at the surface of the film, with Cel9A releasing 40 from the ~ 700 film and Cel5A resulting in only a slight roughening/swelling effect at the surface. Subsequent elevation of the temperature to the Topt in each case resulted in a very limited increase in activity, corresponding to the loss of an additional 60 from the film for Cel9A and 20 from the film for Cel5A, and very weak penetration into and digestion within the bulk of the film, before the activity again ceased. The results for Cel9A and Cel5A contrast sharply with results for Cel45A where very rapid and extensive penetration and digestion within the bulk of the film was observed at 20 C. We speculate that the large differences are due to the use of the thermophilic enzymes far below their optimal temperatures and also the presence of a cellulose binding module (CBM) on Cel45A while the thermophilic enzymes lack a CBM.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- DE-AC05-00OR22725
- OSTI ID:
- 1024687
- Journal Information:
- Biomacromolecules, Vol. 12, Issue 6
- Country of Publication:
- United States
- Language:
- English
Similar Records
Addition of a carbohydrate-binding module enhances cellulase penetration into cellulose substrates
Periplasmic Cytophaga hutchinsonii Endoglucanases Are Required for Use of Crystalline Cellulose as the Sole Source of Carbon and Energy