A need for re-examination of the fibre diffraction data of A-DNA

Sasisekharan, V and Bansal, Manju and Gupta, Goutam (1981) A need for re-examination of the fibre diffraction data of A-DNA. In: Biochemical and Biophysical Research Communications, 102 (3). pp. 1087-1095.

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Abstract

A-DNA pattern, obtained using a flat plat camera, was indexed by Fuller Image on the basis of a c-face centred monoclinic cell with A = 22.24 Å, B = 40.62 Å, C = 28.15 Å and β = 97.0°. A precession photograph of A-DNA which gives an undistorted picture of the lattice, showed that the unit cell parameters as given by Fuller Image were not quite correct. The precession photograph showed a strong meridional reflection (R = 0.00 Å−1) on the 11th layer line. But the occurrence of the meridional reflection on the 11th layer line could not be explained on the basis of the cell parameters given by Fuller Image ; using those cell parameters the reflection which comes closest to the meridian on 11th layer line is at R = 0.025 Å−1. However, a simple interchange of a and b values accounted for the meridional reflection on 11th layer line. The corrected cell parameter refined against 28 strong spots are A = 40.75 Å, B = 22.07 Å, C = 28.16 Å and β = 97.5°. In the new unit cell of A-DNA, the packing arrangement of the two molecules is different from that in the old one. Nonetheless, our earlier contention is again reaffirmed that both right and left-handed A-DNA are stereochemically allowed and consistent with the observed fibre pattern.

Item Type:	Journal Article
Publication:	Biochemical and Biophysical Research Communications
Publisher:	Elsevier Science
Additional Information:	Copy right of this article belongs to Elsevier Science.
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited:	11 Jan 2010 07:28
Last Modified:	19 Sep 2010 05:43
URI:	http://eprints.iisc.ac.in/id/eprint/22827

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