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From Proteopedia
RNA APTAMER COMPLEXED WITH CITRULLINE, NMR
Overview
In a previous study, an RNA aptamer for the specific recognition of arginine was evolved from a parent sequence that bound citrulline specifically. The two RNAs differ at only 3 positions out of 44. The solution structures of the two aptamers complexed to their cognate amino acids have now been determined by two-dimensional nuclear magnetic resonance spectroscopy. Both aptamers contain two asymmetrical internal loops that are not well ordered in the free RNA but that fold into a compact structure upon ligand binding. Those nucleotides common to both RNAs include a conserved cluster of purine residues, three of which form an uneven plane containing a G:G pair, and two other residues nearly perpendicular to that surface. Two of the three variant nucleotides are stacked on the cluster of purines and form a triple contact to the amino acid side chain, whereas the edge of the third variant nucleotide is capping the binding pocket.
About this Structure
Full crystallographic information is available from OCA.
Reference
Structural basis of ligand discrimination by two related RNA aptamers resolved by NMR spectroscopy., Yang Y, Kochoyan M, Burgstaller P, Westhof E, Famulok M, Science. 1996 May 31;272(5266):1343-7. PMID:8650546 Page seeded by OCA on Fri May 2 22:58:52 2008
