1o55
From Proteopedia
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MOLECULAR STRUCTURE OF TWO CRYSTAL FORMS OF CYCLIC TRIADENYLIC ACID AT 1 ANGSTROM RESOLUTION
Overview
The three dimensional structures of cyclic deoxytriadenylic acid, c-d(ApApAp), from two different trigonal crystal forms (space groups P3, and R32) have been determined by x-ray diffraction analysis at 1A, resolution. Both structures were solved by direct methods and refined by, anisotropic least squares refinement to R-factors of 0.109 and 0.137 for, the P3 and R32 forms, respectively. In both crystal forms, each of the two, independent c-d(ApApAp) molecules sits on the crystallographic 3-fold, axis. All four independent c-d(ApApAp) molecules have similar backbone, conformations. The deoxyriboses are in the S-type pucker with, pseudorotation angles ranging from 156.7 degrees to 168.6 degrees and the, bases have anti glycosyl torsion angles (chi falling in two ranges, one at, -104.3 degrees and the other ranging from -141.0 degrees to -143.8, degrees). In the R32 form, a hexahydrated cobalt(II) ion is found to, coordinate through bridging water molecules to N1, N3, and N7 atoms of, three adjacent adenines and oxygen atoms of phosphates. Comparison with, other structures of cyclic oligonucleotides indicates that the sugar, adopts N-type pucker in cyclic dinucleotides and S-type pucker in cyclic, trinucleotides, regardless whether the sugar is a ribose or a deoxyribose.
About this Structure
1O55 is a Protein complex structure of sequences from [1] with CO as ligand. This structure superseeds the now removed PDB entry 415D. Full crystallographic information is available from OCA.
Reference
Molecular structure of two crystal forms of cyclic triadenylic acid at 1A resolution., Gao YG, Robinson H, Guan Y, Liaw YC, van Boom JH, van der Marel GA, Wang AH, J Biomol Struct Dyn. 1998 Aug;16(1):69-76. PMID:9745896
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