137d

[[Image:137d.gif|left|200px]]<br /><applet load="137d" size="350" color="white" frame="true" align="right" spinBox="true"

caption="137d, resolution 1.700&Aring;" />

'''A-DNA DECAMER D(GCGGGCCCGC)-ORTHORHOMBIC CRYSTAL FORM'''<br />

==Overview==

We have determined the structure of the A-DNA decamer d(GCGGGCCCGC) in two crystal forms, orthorhombic and hexagonal, at 1.7- and 1.8-A resolution, respectively. In the orthorhombic form, the fifth guanine residue has nearly trans-trans conformations for the alpha-gamma backbone torsions, as in the isomorphous orthorhombic structure d(CCCGGCCGGG) [Ramakrishnan, B., &amp; Sundaralingam, M. (1993) J. Mol. Biol. 231, 431-444]. However, in the hexagonal form, the eighth cytosine residue adopts the trans-trans conformations for the backbone alpha-gamma torsions, as in the isomorphous hexagonal structure d(ACCGGCCGGT) [Frederick, C. A., Quigley, G. J., Teng, M.-K., Coll, M., van der Marel, G. A., van Boom, J. H., Rich, A., &amp; Wang, A. H.-J. (1989) Eur. J. Biochem. 181, 295-307]. Even though the average helix and base-pair parameters are nearly the same in the two polymorphous crystal forms having the same sequence, many of the base-dependent local helix parameters are quite different. However, in the isomorphous crystal forms, in spite of the differing base sequences, the local helix and base-pair parameters of the duplexes are nearly the same. This indicates that, in crystals, the local conformation of a DNA structure is affected severely by the crystal packing environment rather than by the base sequence.

 

==About this Structure==

137D is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/ ]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=137D OCA].

 

==Reference==

Evidence for crystal environment dominating base sequence effects on DNA conformation: crystal structures of the orthorhombic and hexagonal polymorphs of the A-DNA decamer d(GCGGGCCCGC) and comparison with their isomorphous crystal structures., Ramakrishnan B, Sundaralingam M, Biochemistry. 1993 Oct 26;32(42):11458-68. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=8218212 8218212]

[[Category: Protein complex]]

[[Category: Ramakrishnan, B.]]

[[Category: Sundaralingam, M.]]

[[Category: a-dna]]

[[Category: double helix]]