Analytical method to determine the orientation of rigid spin labels in DNA.
We demonstrate the ability of pulsed electron double resonance (PELDOR) experiments to determine the orientation of spin labels in biological macromolecules. Thus, the distance information usually obtained from PELDOR data can be complemented by the mutual orientation of macromolecular domains. A method to determine the angle beta between the spin label normal and the interspin axis is proposed and analyzed mathematically. The obtained analytical expression allows extraction of angles beta without a fitting procedure if these angles are equal for both nitroxide of biradical. The method was applied to the experimental data gathered on ten spin-labeled DNA samples. The angles estimated from the PELDOR data are in excellent agreement with literature values.
Marko
Andriy
A
Institute of Physical and Theoretical Chemistry, J. W. Goethe University, Max-von-Laue-Str. 7, D-60438 Frankfurt, Germany. marko@prisner.de
Margraf
Dominik
D
Cekan
Pavol
P
Sigurdsson
Snorri Th
ST
Schiemann
Olav
O
Prisner
Thomas F
TF
D003596:Cytosine / Q000737:chemistry; D004247:DNA / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D008958:Models, Molecular; D009589:Nitrogen Oxides / Q000737:chemistry; D009690:Nucleic Acid Conformation; D013113:Spin Labels
D009589:Nitrogen Oxides; D013113:Spin Labels; D003596:Cytosine; D004247:DNA; C039900:nitroxyl