223d: Difference between revisions

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==Overview==

The pyrimidine nucleobase analogue 6H,8H-3,4-dihydropyrimido[4,5-c]-, [1,2]oxazin-7-one (P) is a mimic both of cytosine and thymine, since it, can form stable hydrogen-bonded base-pairs with either guanine or adenine., To investigate the geometric properties of pairing with guanine in a DNA, double helix, the structure of d(CGCGPG)2 has been determined by single, crystal X-ray analysis. The oligonucleotide crystallised as a left-handed, Z-DNA duplex in the orthorhombic space group P2(1)2(1)2(1) with cell, dimensions a = 18.23 A, b = 30.63 A, c = 43.78 A. Refinement using NUCLSQ, with 51 water molecules included in the final model converged at R = 0.179, (Rw = 0.159) for 2798 reflections (F > 2 sigma (F)) in the range 8 A to, 1.7 A. Remarkably, the two P.G pairs in the hexamer duplex are different:, Watson-Crick and wobble types separately illustrate both cytosine-like and, thymine-like behaviour. The result suggests that mutagenesis experiments, involving P and other analogues which display pronounced base-pairing, ambivalence can be used to examine the structural basis of substrate, discrimination by polymerases that is essential to accurate genetic, replication.

The pyrimidine nucleobase analogue 6H,8H-3,4-dihydropyrimido[4,5-c]- [1,2]oxazin-7-one (P) is a mimic both of cytosine and thymine, since it can form stable hydrogen-bonded base-pairs with either guanine or adenine. To investigate the geometric properties of pairing with guanine in a DNA double helix, the structure of d(CGCGPG)2 has been determined by single crystal X-ray analysis. The oligonucleotide crystallised as a left-handed Z-DNA duplex in the orthorhombic space group P2(1)2(1)2(1) with cell dimensions a = 18.23 A, b = 30.63 A, c = 43.78 A. Refinement using NUCLSQ with 51 water molecules included in the final model converged at R = 0.179 (Rw = 0.159) for 2798 reflections (F > 2 sigma (F)) in the range 8 A to 1.7 A. Remarkably, the two P.G pairs in the hexamer duplex are different: Watson-Crick and wobble types separately illustrate both cytosine-like and thymine-like behaviour. The result suggests that mutagenesis experiments involving P and other analogues which display pronounced base-pairing ambivalence can be used to examine the structural basis of substrate discrimination by polymerases that is essential to accurate genetic replication.

==About this Structure==

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Direct observation of two base-pairing modes of a cytosine-thymine analogue with guanine in a DNA Z-form duplex: significance for base analogue mutagenesis., Moore MH, Van Meervelt L, Salisbury SA, Lin PK, Brown DM, J Mol Biol. 1995 Sep 1;251(5):665-73. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=7666418 7666418]

[[Category: Protein complex]]

[[Category: Brown, D.M.]]

[[Category: Brown, D M.]]

[[Category: Lin, P.Kong.Thoo.]]

[[Category: Lin, P Kong Thoo.]]

[[Category: Meervelt, L.Van.]]

[[Category: Meervelt, L Van.]]

[[Category: Moore, M.H.]]

[[Category: Moore, M H.]]

[[Category: Salisbury, S.A.]]

[[Category: Salisbury, S A.]]

[[Category: double helix]]

[[Category: modified]]

[[Category: z-dna]]

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@@ Line 4: / Line 4: @@
 ==Overview==
-The pyrimidine nucleobase analogue 6H,8H-3,4-dihydropyrimido[4,5-c]-, [1,2]oxazin-7-one (P) is a mimic both of cytosine and thymine, since it, can form stable hydrogen-bonded base-pairs with either guanine or adenine., To investigate the geometric properties of pairing with guanine in a DNA, double helix, the structure of d(CGCGPG)2 has been determined by single, crystal X-ray analysis. The oligonucleotide crystallised as a left-handed, Z-DNA duplex in the orthorhombic space group P2(1)2(1)2(1) with cell, dimensions a = 18.23 A, b = 30.63 A, c = 43.78 A. Refinement using NUCLSQ, with 51 water molecules included in the final model converged at R = 0.179, (Rw = 0.159) for 2798 reflections (F &gt; 2 sigma (F)) in the range 8 A to, 1.7 A. Remarkably, the two P.G pairs in the hexamer duplex are different:, Watson-Crick and wobble types separately illustrate both cytosine-like and, thymine-like behaviour. The result suggests that mutagenesis experiments, involving P and other analogues which display pronounced base-pairing, ambivalence can be used to examine the structural basis of substrate, discrimination by polymerases that is essential to accurate genetic, replication.
+The pyrimidine nucleobase analogue 6H,8H-3,4-dihydropyrimido[4,5-c]- [1,2]oxazin-7-one (P) is a mimic both of cytosine and thymine, since it can form stable hydrogen-bonded base-pairs with either guanine or adenine. To investigate the geometric properties of pairing with guanine in a DNA double helix, the structure of d(CGCGPG)2 has been determined by single crystal X-ray analysis. The oligonucleotide crystallised as a left-handed Z-DNA duplex in the orthorhombic space group P2(1)2(1)2(1) with cell dimensions a = 18.23 A, b = 30.63 A, c = 43.78 A. Refinement using NUCLSQ with 51 water molecules included in the final model converged at R = 0.179 (Rw = 0.159) for 2798 reflections (F &gt; 2 sigma (F)) in the range 8 A to 1.7 A. Remarkably, the two P.G pairs in the hexamer duplex are different: Watson-Crick and wobble types separately illustrate both cytosine-like and thymine-like behaviour. The result suggests that mutagenesis experiments involving P and other analogues which display pronounced base-pairing ambivalence can be used to examine the structural basis of substrate discrimination by polymerases that is essential to accurate genetic replication.
 ==About this Structure==
@@ Line 12: / Line 12: @@
 Direct observation of two base-pairing modes of a cytosine-thymine analogue with guanine in a DNA Z-form duplex: significance for base analogue mutagenesis., Moore MH, Van Meervelt L, Salisbury SA, Lin PK, Brown DM, J Mol Biol. 1995 Sep 1;251(5):665-73. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=7666418 7666418]
 [[Category: Protein complex]]
-[[Category: Brown, D.M.]]
+[[Category: Brown, D M.]]
-[[Category: Lin, P.Kong.Thoo.]]
+[[Category: Lin, P Kong Thoo.]]
-[[Category: Meervelt, L.Van.]]
+[[Category: Meervelt, L Van.]]
-[[Category: Moore, M.H.]]
+[[Category: Moore, M H.]]
-[[Category: Salisbury, S.A.]]
+[[Category: Salisbury, S A.]]
 [[Category: double helix]]
 [[Category: modified]]
 [[Category: z-dna]]
-''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jan 29 17:47:48 2008''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 16:21:14 2008''