This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. A multifrequency approach combining high and low ESR frequencies can enable a decomposition of the complex dynamic modes affecting each site label on a protein labeled via site-directed spin-labeling (SDSL). In a recent study on T4 lysozyme using mutagens, to which a spin label is attached at different residues, we showed that the high-field/high-frequency-ESR (HFHF-ESR) experiments could be satisfactorily described by the microscopic order macroscopic disorder (MOMD) model in which only the internal dynamics is present. The slowly relaxing local structure (SRLS) model includes fitting parameters for the overall tumbling rates and internal modes. The MOMD model is a limiting case of SRLS model where the overall tumbling is too slow to affect the appearance of the spectrum. On the slower time scale of the 9GHz spectra both the faster internal modes and the slower overall tumbling are important. These studies have provided evidence for the potential of multifrequency ESR to map out the dynamic structure, on a site to site basis, of a macromolecule. The center has recently installed new HFHF-ESR cw spectrometers with superior signal to noise and temperature stability to previous versions, which will allow us to study the dynamic modes of the system with improved sensitivity and throughput capability over a range of frequencies from 9 to 240GHz. The availability of spectra for analysis over a range of frequencies, although a significant computational challenge, will provide detailed insights into the dynamic modes of the system. The implementation of continuously variable coupling to all of our resonators originally developed at 95GHz will be a crucial advance to further improve the sensitivity of our HFHF ESR spectrometers.

Agency
National Institute of Health (NIH)
Institute
National Center for Research Resources (NCRR)
Type
Biotechnology Resource Grants (P41)
Project #
2P41RR016292-11
Application #
8363927
Study Section
Special Emphasis Panel (ZRG1-BCMB-K (40))
Project Start
2011-09-01
Project End
2012-08-31
Budget Start
2011-09-01
Budget End
2012-08-31
Support Year
11
Fiscal Year
2011
Total Cost
$4,623
Indirect Cost
Name
Cornell University
Department
Chemistry
Type
Schools of Arts and Sciences
DUNS #
872612445
City
Ithaca
State
NY
Country
United States
Zip Code
14850
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