title: Site-specific DNA structural and dynamic features revealed by nucleotide-independent nitroxide probes.
abstract: In site-directed spin labeling, a covalently attached nitroxide probe containing a chemically inert unpaired electron is utilized to obtain information on the local environment of the parent macromolecule. Studies presented here examine the feasibility of probing local DNA structural and dynamic features using a class of nitroxide probes that are linked to chemically substituted phosphorothioate positions at the DNA backbone. Two members of this family, designated as R5 and R5a, were attached to eight different sites of a dodecameric DNA duplex without severely perturbing the native B-form conformation. Measured X-band electron paramagnetic resonance (EPR) spectra, which report on nitroxide rotational motions, were found to vary depending on the location of the label (e.g., duplex center vs termini) and the surrounding DNA sequence. This indicates that R5 and R5a can provide information on the DNA local environment at the level of an individual nucleotide. As these probes can be attached to arbitrary nucleotides within a nucleic acid sequence, they may provide a means to "scan" a given DNA molecule in order to interrogate its local structural and dynamic features.
authors: Department of Chemistry, University of Southern California, Los Angeles, California, USA.
authors: Anna M
authors: AM
authors: Popova
authors: Tamás
authors: T
authors: Kálai
authors: Kálmán
authors: K
authors: Hideg
authors: Peter Z
authors: PZ
authors: Qin
mesh_terms: D015342:DNA Probes / Q000737:chemistry* / Q000378:metabolism; D005609:Free Radicals / Q000737:chemistry / Q000378:metabolism; D009589:Nitrogen Oxides / Q000737:chemistry* / Q000378:metabolism; D009690:Nucleic Acid Conformation; D009692:Nucleic Acid Heteroduplexes / Q000737:chemistry* / Q000378:metabolism; D054735:Phosphorothioate Oligonucleotides / Q000737:chemistry* / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization; D013113:Spin Labels; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D013816:Thermodynamics
chemical_list: D015342:DNA Probes; D005609:Free Radicals; D009589:Nitrogen Oxides; D009692:Nucleic Acid Heteroduplexes; D054735:Phosphorothioate Oligonucleotides; D013113:Spin Labels; C039900:nitroxyl