Researchers have long known that the atoms inside protein molecules move, but they couldn’t see what form the motion takes. Now neutron scattering and computing research at Oak Ridge National Laboratory (ORNL) has classified the motions into three distinct classes— localized diffusion, methyl group rotations, and jumps.
Defining the atomic-level motions that underpin protein functioning will guide scientists as they explore how the motions determine the functions of proteins. The ORNL–University of Tennessee research team was directed by Governor’s Chair scholars Jeremy Smith (of the Biosciences Division) and Alexei Sokolov (of the Chemical Sciences Division).
The team analyzed the protein lysozyme, a natural antibacterial enzyme found in tears and saliva. They expect the combined simulation and neutron scattering approach they used to have a wide impact in the neutron scattering community, aiding research in areas such as biofuels and environmental cleanup and on nonbiological materials such as polymers.
“The analysis and interpretation of neutron scattering spectra are always difficult for complex molecules such as proteins,” said Smith, director of ORNL’s Center for Molecular Biophysics. “We’ve performed experiments and then shown that simulation can provide a clear view of them. It allows us to see through the complexity and find out what motions are going on. First, we found that experiment and simulation agreed perfectly with each other, which is remarkable. Second, the simulations told us that this type of neutron scattering can be interpreted in a very simple way.”
The research was conducted by Liang Hong, with support from Benjamin Lindner and Nikolai Smolin, all of the Biosciences Division. Neutron scattering experiments were conducted at the BASIS instrument at the Spallation Neutron Source and at NIST.
Reference: Hong, L., et al. 2011. “Three Classes of Motion in the Dynamic Neutron-Scattering Susceptibility of a Globular Protein,” Physical Review Letters 107(14), 148102.