104d: Difference between revisions

[[Image:104d.jpg|left|200px]]<br /><applet load="104d" size="350" color="white" frame="true" align="right" spinBox="true"  

Hybrid duplexes and chimeric duplexes containing hybrid segments linked to, pure DNA (or pure RNA) segments are involved in transcription and, replication, as well as reverse transcription. A complete understanding of, the mechanism of these processes requires detailed information on such, duplexes and the junctions between duplexes of differing structure. Using, two-dimensional NMR, restrained molecular dynamics and mechanics, and, back-calculation refinement against the nuclear Overhauser effect spectra, at various mixing times, we have determined the solution structure of the, chimeric duplex [r(cgcg)d-(TATACGCG)]2 containing a pure DNA segment in, the center of a hybrid duplex. The solution structure differs from the, previously determined X-ray structure of the analogous duplex, [r(gcg)d(TATACGC)]2, which was found to be A-form throughout [Wang, A.H.-J., et al. (1982) Nature 299, 601-604]. The basic features of the, solution structure are (a) the RNA residues are all A-form with C3'-endo, sugar conformations, (b) the central DNA segment is B-form, (c) the, transition from A-form RNA sugar conformations to B-form DNA sugar, conformations involves only the dT5 base step, and (d) although the sugar, conformations of the DNA residues A6-G12 are closer to B-form, the basic, helical properties of the peripheral RNA.DNA hybrid segments are closer to, typical A-form than to B-form.

104D 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=104D OCA].  

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