6pvx | pdb_00006pvx

RNase A in complex with p5U

spinqualitylabelsall models 6pvx, resolution 1.55Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 6pvx is a 2 chain structure with sequence from Bos taurus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.55Å Ligands: U5F Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed Adenosine and uridine 5'-tetra- and 5'-pentaphosphates were synthesized from an activated tetrametaphosphate ([PPN]2[P4O11], [PPN]2[1], PPN = bis(triphenylphosphine)iminium) and subsequently tested for inhibition of the enzymatic activity of ribonuclease A (RNase A). Reagent [PPN]2[1] reacts with unprotected uridine and adenosine in the presence of a base under anhydrous conditions to give nucleoside tetrametaphosphates. Ring opening of these intermediates with tetrabutylammonium hydroxide ([TBA][OH]) yields adenosine and uridine tetraphosphates (p4A, p4U) in 92% and 85% yields, respectively, from the starting nucleoside. Treatment of ([PPN]2[1]) with AMP or UMP yields nucleoside-monophosphate tetrametaphosphates (cp4pA, cp4pU) having limited aqueous stability. Ring opening of these ultraphosphates with [TBA][OH] yields p5A and p5U in 58% and 70% yield from AMP and UMP, respectively. We characterized inorganic and nucleoside-conjugated linear and cyclic oligophosphates as competitive inhibitors of RNase A. Increasing the chain length in both linear and cyclic inorganic oligophosphates resulted in improved binding affinity. Increasing the length of oligophosphates on the 5' position of adenosine beyond three had a deleterious effect on binding. Conversely, uridine nucleotides bearing 5' oligophosphates saw progressive increases in binding with chain length. We solved X-ray cocrystal structures of the highest affinity binders from several classes. The terminal phosphate of p5A binds in the P1 enzymic subsite and forces the oligophosphate to adopt a convoluted conformation, while the oligophosphate of p5U binds in several extended conformations, targeting multiple cationic regions of the active-site cleft. Nucleoside Tetra- and Pentaphosphates Prepared Using a Tetraphosphorylation Reagent Are Potent Inhibitors of Ribonuclease A.,Shepard SM, Windsor IW, Raines RT, Cummins CC J Am Chem Soc. 2019 Nov 11. doi: 10.1021/jacs.9b09760. PMID:31651164 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Ribonuclease 3D structures

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