G-Quadruplex formation of deoxyguanosine in the presence of alkaline earth metal ions studied by electrospray ionization mass spectrometry

2011 ◽  
Vol 25 (14) ◽  
pp. 2095-2098 ◽  
Author(s):  
M. Sravani ◽  
V. Nagaveni ◽  
S. Prabhakar ◽  
M. Vairamani
Keyword(s):  
Mass Spectrometry ◽  
Electrospray Ionization ◽  
Electrospray Ionization Mass Spectrometry ◽  
Alkaline Earth ◽  
Earth Metal ◽  
Alkaline Earth Metal ◽  
Ionization Mass ◽  
Alkaline Earth Metal Ions ◽  
G Quadruplex ◽  
Quadruplex Formation

Nuclear magnetic resonance and mass spectrometry studies of 2′,3′,5′-O-triacetylguanosine self-assembly in the presence of alkaline earth metal ions (Ca2+, Sr2+, Ba2+)

2011 ◽  
Vol 89 (7) ◽  
pp. 835-844 ◽  
Author(s):  
Irene C.M. Kwan ◽  
Yi-Min She ◽  
Gang Wu
Keyword(s):  
Mass Spectrometry ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Metal Ions ◽  
Self Assembly ◽  
Alkaline Earth ◽  
Earth Metal ◽  
Alkaline Earth Metal ◽  
Alkaline Earth Metal Ions ◽  
Nuclear Magnetic

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]8M2+ (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]8Sr2+. 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° 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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