959326-89-7Relevant articles and documents
Site-directed spin-labeling of DNA by the azide-alkyne 'Click' reaction: Nanometer distance measurements on 7-deaza-2′-deoxyadenosine and 2′-deoxyuridine nitroxide conjugates spatially separated or linked to a 'dA-dT' base pair
Ding, Ping,Wunnicke, Dorith,Steinhoff, Heinz-Juergen,Seela, Frank
supporting information; scheme or table, p. 14385 - 14396 (2011/03/22)
Nucleobase-directed spin-labeling by the azide-alkyne 'click' (CuAAC) reaction has been performed for the first time with oligonucleotides. 7-Deaza-7-ethynyl-2′-deoxyadenosine (1) and 5-ethynyl-2′- deoxyuridine (2) were chosen to incorporate terminal triple bonds into DNA. Oligonucleotides containing 1 or 2 were synthesized on a solid phase and spin labeling with 4-azido-2,2,6,6-tetramethylpiperidine 1-oxyl (4-azido-TEMPO, 3) was performed by post-modification in solution. Two spin labels (3) were incorporated with high efficiency into the DNA duplex at spatially separated positions or into a 'dA-dT' base pair. Modification at the 5-position of the pyrimidine base or at the 7-position of the 7-deazapurine residue gave steric freedom to the spin label in the major groove of duplex DNA. By applying cw and pulse EPR spectroscopy, very accurate distances between spin labels, within the range of 1-2nm, were measured. The spin-spin distance was 1.8A±0. 2nm for DNA duplex 17(dA7,10)·11 containing two spin labels that are separated by two nucleotides within one individual strand. A distance of 1.4A±0.2nm was found for the spin-labeled 'dA-dT' base pair 15(dA7)·16(dT6). The 'click' approach has the potential to be applied to all four constituents of DNA, which indicates the universal applicability of the method. New insights into the structural changes of canonical or modified DNA are expected to provide additional information on novel DNA structures, protein interaction, DNA architecture, and synthetic biology. 'Clicked' DNA spin labels: Spin labels (spheres in the figure) have been incorporated by click chemistry into DNA duplexes at spatially separated positions or into a 'dA-dT' base pair with high efficiency. Very accurate distances between spin labels, within a range of 1-2nm, were measured by continuous wave and pulse EPR spectroscopy. Copyright
