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biologyModerator: BioTeam
3 posts • Page 1 of 1
It might be tetrameric DNA.
I'm giving the abstract of this research by " Kalle Gehring*, Jean-Louis Leroy & Maurice Guéron Groupe de Biophysique de I'école Polytechnique et de I'URA D1254 du CNRS, 91128 Palaiseau, France * *Present address: Laboratoire de RMN, ICSN, CNRS, 91198 Gif-sur-Yvette, France." OLIGOMERS containing tracts of cytidine form hemiprotonated base pairs at acid pH and have been considered to be double-stranded. We have solved the structure of the DNA oligomer 5'-d(TCCCCC) at acid pH and find that it is a four-stranded complex in which two base-paired parallel-stranded duplexes are intimately associated, with their base pairs fully intercalated. The relative orientation of the duplexes is antiparallel, so that each base pair is face-to-face with its neighbours. The NMR spectrum displays only six spin systems, showing that the structure is highly symmetrical on the NMR timescale; the four strands are equivalent. A model derived by energy minimization and con-strained molecular dynamics shows excellent compatibility with the observed nuclear Overhauser effects (NOEs) particularly for the very unusual inter-residue sugar-sugar NOEs HI'-HI', Hl'-H2" and H1'-H4'. These NOEs are probably diagnostic for such tetrameric structures. Thanx! Dip Jyoti Chakraborty
3 posts • Page 1 of 1
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