225d: Difference between revisions

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==Overview==

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 constrained molecular dynamics shows, excellent compatibility with the observed nuclear Overhauser effects, (NOEs) particularly for the very unusual inter-residue sugar-sugar NOEs, H1'-H1', H1'-H2" and H1'-H4'. These NOEs are probably diagnostic for such, tetrameric structures.

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 constrained molecular dynamics shows excellent compatibility with the observed nuclear Overhauser effects (NOEs) particularly for the very unusual inter-residue sugar-sugar NOEs H1'-H1', H1'-H2" and H1'-H4'. These NOEs are probably diagnostic for such tetrameric structures.

==About this Structure==

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[[Category: Gehring, K.]]

[[Category: Gueron, M.]]

[[Category: Leroy, J.L.]]

[[Category: Leroy, J L.]]

[[Category: dna]]

[[Category: intercalated cytosine tetrad]]

[[Category: nmr]]

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@@ Line 4: / Line 4: @@
 ==Overview==
-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 constrained molecular dynamics shows, excellent compatibility with the observed nuclear Overhauser effects, (NOEs) particularly for the very unusual inter-residue sugar-sugar NOEs, H1'-H1', H1'-H2" and H1'-H4'. These NOEs are probably diagnostic for such, tetrameric structures.
+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 constrained molecular dynamics shows excellent compatibility with the observed nuclear Overhauser effects (NOEs) particularly for the very unusual inter-residue sugar-sugar NOEs H1'-H1', H1'-H2" and H1'-H4'. These NOEs are probably diagnostic for such tetrameric structures.
 ==About this Structure==
@@ Line 14: / Line 14: @@
 [[Category: Gehring, K.]]
 [[Category: Gueron, M.]]
-[[Category: Leroy, J.L.]]
+[[Category: Leroy, J L.]]
 [[Category: dna]]
 [[Category: intercalated cytosine tetrad]]
 [[Category: nmr]]
-''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jan 29 17:47:56 2008''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 16:21:14 2008''