期刊
CANADIAN JOURNAL OF CHEMISTRY
卷 89, 期 7, 页码 835-844出版社
CANADIAN SCIENCE PUBLISHING, NRC RESEARCH PRESS
DOI: 10.1139/V10-179
关键词
nuclear magnetic resonance; mass spectrometry; self-assembly; guanosine (G); alkaline earth metal; G-quartet; structural elucidation
资金
- Natural Sciences and Engineering Research Council of Canada (NSERC)
- NSERC
We report structural determination of cation-templated self-assembly of a guanosine derivative, 2',3',5'-O-triacetylguanosine (TAG), in the presence of three alkaline earth metal ions (Ca2+, Sr2+, and Ba2+) in CDCl3. Using a combination of nuclear magnetic resonance (NMR) and electrospray ionization mass spectrometry (ESI-MS) methods, we have found that TAG molecules form discrete octamers in the form of [TAG](8)M2+ (M2+ = Ca2+, Sr2+, and Ba2+), which is composed of two G-quartets and a sandwiched metal ion. We have determined the ability of the three alkaline earth metal ions to promote TAG self-assembly (relative binding affinity) to be Sr2+ >> Ba2+ > Ca2+. More importantly, we have used two-dimensional (2D) NMR methods to determine the structural details of [TAG](8)Sr2+. In particular, we found that each octamer consists of an all-anti G-quartet stacking on top of an all-syn G-quartet in a tail-to-head fashion with a twist angle of 45 degrees between the two G-quartets. This TAG octamer structure represents a unique case quite different from other lipophilic guanosine octamers reported in the literature.
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