Nuclear Resonance Spectroscopy of Biomolecules

Northeastern University, Boston MA

Investigators

Abstract

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. Ultrahigh resolution synchrotron-based measurements of X-ray absorption near the 14.4keV 57-Fe Moessbauer resonance reveal the complete vibrational spectrum of Fe.. NRVS provides quantitative information on vibrational amplitudes as well as frequencies and allows one to deduce the direction of Fe motion from measurements on oriented samples. Observations will include structurally sensitive modes, or vibrational spectators, that are not easily measurable using other techniques. A theme of particular interest is the identification and characterization of vibrational participants, modes directly involved in biological reactions. Fe is the reactive center of many biological reactions, and reactive modes involving the Fe must contribute to the NRVS signal. Measurements on Fe porphyrin powders and single crystals, coupled with normal mode analysis, will establish the character of observed modes, including participants, and provide a basis for interpreting measurements on proteins. An issue of particular interest in the protein studies is whether vibrations remain localized at the active site, or acquire a more global character by vibrational mixing with the surrounding polypeptide, and the structural factors responsible for this local or global character. The project will have a broad impact in at least three areas: (1) Work on this project is an outstanding training opportunity. (2) The project establishes collaborative ties between disciplines and institutions, necessitating diverse expertise in synthetic chemistry, molecular biology, and modern computational approaches. (3) Development and dissemination of next-generation instrumentation at a multi-user facility is an integral aspect of the proposed work, as Instrumental advances developed in support of the proposed work become available to other synchrotron users. This award is co-sponsored by the Physics Division in the Mathematical and Physical Science Directorate and the Division of Molecular and Cellular Biosciences in the Directorate for Biological Sciences.