1n5c

[[Image:1n5c.gif|left|200px]]<br /><applet load="1n5c" size="450" color="white" frame="true" align="right" spinBox="true"

caption="1n5c, resolution 1.79&Aring;" />

'''Crystal Structure Analysis of the B-DNA Dodecamer CGCGAATT(ethenoC)GCG'''<br />

==Overview==

Exocyclic DNA adducts are formed from metabolites of chemical carcinogens, and have also been detected as endogenous lesions in human DNA. The, exocyclic adduct 3,N(4)-etheno-2'-deoxycytidine (epsilon dC), positioned, opposite deoxyguanosine in the B-form duplex of the dodecanucleotide, d(CGCGAATTepsilonCGCG), has been crystallographically characterized at, 1.8A resolution. This self-complementary oligomer crystallizes in space, group P3(2)12, containing a single strand in the asymmetric unit. The, crystal structure was solved by isomorphous replacement with the, corresponding unmodified dodecamer structure. Exposure of both structures, to identical crystal packing forces allows a detailed investigation of the, influence of the exocyclic base adduct on the overall helical structure, and local geometry. Structural changes are limited to the epsilon C:G and, adjacent T:A and G:C base-pairs. The standard Watson-Crick base-pairing, scheme, retained in the T:A and G:C base-pairs, is blocked by the etheno, bridge in the epsilon C:G pair. In its place, a hydrogen bond involving O2, of epsilon C and N1 of G is present. Comparison with an epsilon, dC-containing NMR structure confirms the general conformation reported for, epsilon C:G, including the hydrogen bonding features. Superposition with, the crystal structure of a DNA duplex containing a T:G wobble pair shows, similar structural changes imposed by both mismatches. Evaluation of the, hydration shell of the duplex with bond valence calculations reveals two, sodium ions in the crystal.

 

==About this Structure==

1N5C is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/ ] with NA as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1N5C OCA].

 

==Reference==

Crystallographic characterization of an exocyclic DNA adduct: 3,N4-etheno-2'-deoxycytidine in the dodecamer 5'-CGCGAATTepsilonCGCG-3'., Freisinger E, Fernandes A, Grollman AP, Kisker C, J Mol Biol. 2003 Jun 13;329(4):685-97. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=12787670 12787670]

[[Category: Protein complex]]

[[Category: Fernandes, A.]]

[[Category: Freisinger, E.]]

[[Category: Grollman, A.P.]]

[[Category: Kisker, C.F.]]

[[Category: NA]]

[[Category: 3]]

[[Category: b form double helix]]

[[Category: n4-etheno-2'-cytidine modification opposite g]]