Dynamics and Ordering in a Spin-Labeled Oligonucleotide Observed by 220GHz Electron Paramagnetic Resonance
| Autor: | Francis Johnson, Stephen V. Kolaczkowski, Chamakura V.N.S. Varaprasad, Alex Perry, David E. Budil, Phyllis R. Strauss |
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| Jazyk: | angličtina |
| Předmět: |
Pentamer
Biophysics 010402 general chemistry 01 natural sciences Spectral line law.invention 03 medical and health sciences chemistry.chemical_compound law Anisotropy Electron paramagnetic resonance 030304 developmental biology 0303 health sciences Quantitative Biology::Biomolecules Aqueous solution Base Sequence Electron Spin Resonance Spectroscopy Atmospheric temperature range 0104 chemical sciences Crystallography Monomer chemistry Oligodeoxyribonucleotides Nucleic Acid Conformation Thermodynamics Spin Labels Macromolecule Research Article |
| Zdroj: | Biophysical Journal. (1):430-438 |
| ISSN: | 0006-3495 |
| DOI: | 10.1016/S0006-3495(00)76605-7 |
| Popis: | The dynamics of a newly synthesized cytosine spin-label and the spin-labeled pentamer TTC*TT have been observed by high-frequency (220GHz) electron paramagnetic resonance (EPR) in aqueous solution at ambient temperature using only nanomolar amounts of spin-label. Temperature studies were carried out for both labeled species in buffer containing glycerol. The motion of the spin-labeled monomer could be fitted using a model of fully anisotropic rotation (FAR) over the entire temperature range studied. In the single-stranded pentamer, the high-field spectra are best interpreted using a model of microscopic ordering with macroscopic disorder (MOMD) with the probe in a highly nonpolar environment. The observed local order parameters of 0.60–0.70 suggest a micelle-like structure in which the label is tightly packed with the hydrophobic bases. These preliminary studies illustrate how the excellent orientation selectivity of high-field EPR provides new dynamic information about local base motions in DNA, and also how high-field EPR of spin-labels allows one to discriminate accurately between the effects of local versus global motions in spin-labeled macromolecules. |
| Databáze: | OpenAIRE |
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