06/22/2013
How Amines Penetrate Cellulose Fibers and Make Cellulose Accessible for Bioconversion
The Science
Cellulose is a major component of biomass and the primary biomass component being studied for biofuel production. However, cellulose fibers are extremely resistant to solvents, preventing enzymes, which are needed for conversion to products, from entering the fibers. Ammonia and simple organic amine molecules are well-known exceptions to this rule, but the mechanism by which they make cellulose fibers accessible is not understood. New research by an international team led by scientists at Oak Ridge National Laboratory (ORNL) combines neutron fiber diffraction and computational simulation to show how ethylene diamine (EDA, a representative amine solvent) binds to cellulose fibers. EDA disrupts the hydrogen-bonding pattern of naturally occurring cellulose by accepting a strong hydrogen-bond from the O6 hydroxymethyl group as the conformation of this group is rotated from tg to gt. Experimental neutron diffraction data for EDA-cellulose complexes were the starting point for quantum chemical construction of optimized atomic-level structures that were then studied using computational molecular dynamics simulations. The results show how EDA disrupts normal hydrogen bonding in cellulose fibers, and the MD simulations explain the dynamic nature of EDA action.
The Impact
Cellulose has potential as an abundant and renewable material and carbon feedstock resource, but its industrial processing is difficult because it has a melting point that is above its decomposition temperature and it is inert to most solvents. These results will help optimize techniques for breakdown of cellulose fibers to convert them on a large scale to biofuels and other renewable products. The research is featured on the cover of the August 2013 issue of the journal Cellulose and was carried out at ORNL; the French National Center for Scientific Research (CNRS) and Institut Laue Langevin in Grenoble, France; Los Alamos National Laboratory; Keele University; University of Tokyo; and Kyung Hee University in the Republic of Korea.
BER Program Manager
Amy Swain
U.S. Department of Energy, Biological and Environmental Research (SC-33)
Biological Systems Science Division
[email protected]
References
Sawada, D., Y. Nishiyama, L. Petridis, R. Parthasarathi, S. Gnanakaran, V. T. Forsyth, M. Wada, and P. Langan. 2013. “Structure and Dynamics of a Complex of Cellulose with EDA: Insights into the Action of Amines on Cellulose,” Cellulose 20 , 1563–71. DOI: 10.1007/s10570-013-9974-7.