This experimental program will exploit technological advances that establish nuclear resonance vibrational spectroscopy (NRVS) as a site-specific, quantitative probe for vibrational dynamics in iron-containing proteins and model compounds. NRVS, based on the iron-57 Mossbauer transition at 14.4 keV, provides quantitative information on vibrational amplitudes as well as frequencies. The direction of iron motion can be deduced from measurements on oriented samples. The quantitative experimental information obtained from NRVS provides a detailed benchmark for evaluating the results of quantum chemical vibrational calculations, which in turn provide a means to identify observed vibrational modes, including important structural markers that are not observed with other available experimental methods. Reactive modes also contribute to the NRVS signal, which will allow the group to quantify the energetic contributions of heme doming to biomolecular reactions. Through comparison with computational results, the group will assess whether vibrations remain localized at the active site, or acquire a more global character by vibrational mixing with the surrounding polypeptide. Comparison with conventional Mossbauer measurements will make it possible to explore the timescales for dynamical processes at the active sites of selected proteins.
Work on this project is an outstanding training opportunity. Undergraduate students, graduate students, and postdocs will obtain interdisciplinary training in biomolecular physics and cutting-edge synchrotron technologies, contribute to the development of a new spectroscopic tool that will have a significant impact on protein science, and gain exposure to the unique culture of synchrotron science. Development and exploitation of NRVS involves an interdisciplinary team of physicists, bioinorganic chemists, synthetic chemists, and computational scientists at national laboratories, universities, and undergraduate institutions. Development and dissemination of next-generation instrumentation at a multi-user facility is an integral aspect of the proposed work. Instrumental advances developed in support of the proposed work will become available to other synchrotron users.
This project is jointly supported by the Division of Physics in the Directorate for Mathematical and Physical Sciences and the Division of Molecular and Cellular Biosciences in the Directorate for Biological Sciences.
