Neutrons Help Decipher Enzyme Function for Cellulosic Conversion
(Technical University of Munich/Ethanol Producer Magazine) … Using neutrons, researchers have now investigated the reaction mechanism of an important class of enzymes: the glycosidases. The measurements were made at the neutron sources in Los Alamos and Oak Ridge (USA), as well as at the research neutron source FRM II of the Technical University of Munich (TUM). The results provide the key to improving large-scale technical processing of biomass.
When producing synthetics, intermediate chemical products or biofuels from biomass, hemicellulose, a large polysaccharide abundant in plant cell walls, must first be broken down to monomeric sugars. In contrast to the uncatalyzed reaction in neutral solution, enzymes like glycosidases are able to speed up the decomposition reaction up to 18 orders of magnitude.
The biomass is typically pretreated in a very alkaline environment. However, natural enzymes develop their maximum activity in mildly acidic environments. An important research goal is thus to alter these enzymes in a manner to allow them to function effectively in a basic environment.
During their work they discovered that the decisive step depends on the orientation of one specific amino acid side chain, the free carboxyl group of a glutamic acid. When it turns down and away from the substrate, it can take over a proton from a water molecule. When the carboxyl group turns upward, the acidity is strengthened and the proton is transferred to the substrate. READ MORE and MORE Abstract (Proceedings of the National Academy of Sciences)