We propose to replace the Beckman Model E Analysis Ultracentrifuge with the new Beckman Optima XL-A Analytical Ultracentrifuge. This will maintain state-of-the-art instrumentation and facilitate physical biochemical analysis of numerous protein and nucleic acid systems currently under study in the laboratories of the proposed user group. Analytical ultracentrifugation is the best technique for studying associating macromolecular systems and is extremely useful for elucidating the interaction, size, and shape of small molecules, proteins and nucleic acids. Three primary and at least five secondary users will utilize the requested instrumentation in a variety of projects. Major projects include: 1) tubulin polymer formation and microtubule- associated protein self-association, 2) specificity of drug- nucleic acid interactions, 3) assembly of amino-tRNA syntheses complexes, 4) protein-RNA interactions and 5) secretory protein association. Minor projects include: 6) redox-electron carrier protein association, 7) molecular studies of secreted glycoproteins and 8) specificity of histone-DNA interactions. Acquisition of the requested equipment will have an immediated and significant impact on each of the projects listed in this proposal. The impact will include: 1) increased access to analytical ultracentrifugation for routine sedimentation velocity and equilibrium analysis, 2) access to rapid data acquisition and analysis through an interfaced PS/2 computer system, and 3) support for maintenance and repair of the ultracentrifuge. The analytical ultracentrifuge work is complemented by a variety of other biophysical approaches including circular dichroism, fluorescence spectroscopy, differential scanning calorimetry, stopped-flow kinetics, electron microscopy, and molecular biology, protein engineering. The applicants have an established record of shared instrumentation and of active collaboration in their research programs. The Optima XL-A will be only functioning analytical ultracentrifuge in the State of Mississippi.
