Spin polarized neutron crystallography of proteins

Protein crystallography is an established technique for determining protein structures. X-ray protein crystallography is the dominant technique, as the incredibly high flux of modern light sources allows researchers to collect data very quickly using very small crystals. In comparison, neutron crystallography has many unique advantages (due to the neutrons sensitivity to isotopes and light nuclei) but is limited by the low flux available at neutron sources. The spin dependence of neutron scattering provides an opportunity to overcome the flux limitations of neutron sources, expanding the number of protein systems that can be studied, improving the signal to noise, and enabling novel measurement techniques to determine the location of hydrogen atoms. At Oak Ridge National Laboratory (ORNL), a program has been underway to develop Dynamic Nuclear Polarization (DNP) techniques, and apply them to neutron scattering, especially Neutron Macromolecular Crystallography of proteins. The status and results of the DNP program at ORNL will be discussed, with an emphasis on the use of DNP to enhance measurements of diffraction from protein crystals. (author)