Internal Sodium Ions and Water Molecules in Guanine Quadruplexes: Magnetic Relaxation Dispersion Studies of [d(G3T4G3)]2 and [d(G4T4G4)]2
(2008) In Biochemistry 47(46). p.12219-12229- Abstract
- The structural stability of guanine quadruplexes depends critically on an unusual configuration of dehydrated Na+ or K+ ions, closely spaced along the central axis of the quadruplex. Crystallography and NMR spectroscopy indicate that these internal ions can be located between the G-quartet planes as well as in the thymine loops, but the precise ion coordination has been firmly established in only a few cases. Here, we examine the bimolecular diagonal-looped foldback quadruplexes [d(G3T4G3)]2 (Q3) and [d(G4T4G4)]2 (Q4) by 2H, 17O, and 23Na magnetic relaxation dispersion (MRD). The MRD data indicate that both quadruplexes contain Na+ ions between the T4 loops and the terminal G-quartets and that these ions have one water ligand. These ions... (More)
- The structural stability of guanine quadruplexes depends critically on an unusual configuration of dehydrated Na+ or K+ ions, closely spaced along the central axis of the quadruplex. Crystallography and NMR spectroscopy indicate that these internal ions can be located between the G-quartet planes as well as in the thymine loops, but the precise ion coordination has been firmly established in only a few cases. Here, we examine the bimolecular diagonal-looped foldback quadruplexes [d(G3T4G3)]2 (Q3) and [d(G4T4G4)]2 (Q4) by 2H, 17O, and 23Na magnetic relaxation dispersion (MRD). The MRD data indicate that both quadruplexes contain Na+ ions between the T4 loops and the terminal G-quartets and that these ions have one water ligand. These ions exchange with external ions on a time scale of 10−60 μs at 27 °C, while their highly ordered water ligands have residence times in the range 10−8−10−6 s. The MRD data indicate that Q4 contains three Na+ ions in the stem sites, in agreement with previous solid-state 23Na NMR findings but contrary to the only crystal structure of this quadruplex. For Q3, the MRD data suggest a less symmetric coordination of the two stem ions. In both quadruplexes, the stem ions have residence times of 0.6−1.0 ms at 27 °C. The equilibrium constant for Na+ → K+ exchange is ∼4 for both loop and stem sites in Q3, in agreement with previous 1H NMR findings. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/1270164
- author
- Snoussi, Karim LU and Halle, Bertil LU
- organization
- publishing date
- 2008
- type
- Contribution to journal
- publication status
- published
- subject
- in
- Biochemistry
- volume
- 47
- issue
- 46
- pages
- 12219 - 12229
- publisher
- The American Chemical Society (ACS)
- external identifiers
-
- wos:000260790600031
- scopus:56249115189
- ISSN
- 0006-2960
- DOI
- 10.1021/bi801657s
- language
- English
- LU publication?
- yes
- id
- 8f8b0d10-beda-44f5-80f1-b6bc622a8c31 (old id 1270164)
- alternative location
- http://dx.doi.org/10.1021/bi801657s
- date added to LUP
- 2016-04-01 11:38:55
- date last changed
- 2022-01-26 08:11:08
@article{8f8b0d10-beda-44f5-80f1-b6bc622a8c31, abstract = {{The structural stability of guanine quadruplexes depends critically on an unusual configuration of dehydrated Na+ or K+ ions, closely spaced along the central axis of the quadruplex. Crystallography and NMR spectroscopy indicate that these internal ions can be located between the G-quartet planes as well as in the thymine loops, but the precise ion coordination has been firmly established in only a few cases. Here, we examine the bimolecular diagonal-looped foldback quadruplexes [d(G3T4G3)]2 (Q3) and [d(G4T4G4)]2 (Q4) by 2H, 17O, and 23Na magnetic relaxation dispersion (MRD). The MRD data indicate that both quadruplexes contain Na+ ions between the T4 loops and the terminal G-quartets and that these ions have one water ligand. These ions exchange with external ions on a time scale of 10−60 μs at 27 °C, while their highly ordered water ligands have residence times in the range 10−8−10−6 s. The MRD data indicate that Q4 contains three Na+ ions in the stem sites, in agreement with previous solid-state 23Na NMR findings but contrary to the only crystal structure of this quadruplex. For Q3, the MRD data suggest a less symmetric coordination of the two stem ions. In both quadruplexes, the stem ions have residence times of 0.6−1.0 ms at 27 °C. The equilibrium constant for Na+ → K+ exchange is ∼4 for both loop and stem sites in Q3, in agreement with previous 1H NMR findings.}}, author = {{Snoussi, Karim and Halle, Bertil}}, issn = {{0006-2960}}, language = {{eng}}, number = {{46}}, pages = {{12219--12229}}, publisher = {{The American Chemical Society (ACS)}}, series = {{Biochemistry}}, title = {{Internal Sodium Ions and Water Molecules in Guanine Quadruplexes: Magnetic Relaxation Dispersion Studies of [d(G3T4G3)]2 and [d(G4T4G4)]2}}, url = {{http://dx.doi.org/10.1021/bi801657s}}, doi = {{10.1021/bi801657s}}, volume = {{47}}, year = {{2008}}, }