ORNL leads research on glycosidases

In Tennessee, 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.

In the context of an international collaborative project, a team of researchers led by Andrey Kovalevsky, scientist at the Oak Ridge National Laboratory, has now determined the structure of a glycosidase with hitherto unprecedented accuracy. One of the three neutron sources used in the project was the research neutron source FRM II at TU Munich.

The scientists analyzed the structure of the glycosidase using neutron scattering on enzyme crystals. They investigated the structure at various pH levels and in a complex with a ligand molecule. The insight gained from the neutron scattering experiments was used as a starting point for molecular dynamics simulations.

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.