Nucleoside Tetra- and Pentaphosphates Prepared Using a Tetraphosphorylation Reagent Are Potent Inhibitors of Ribonuclease A
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Author(s)
Shepard, Scott M.
Windsor, Ian William
Raines, Ronald T
Cummins, Christopher C
Date Issued
October 2019
Journal
Journal of the American Chemical Society
Publisher
American Chemical Society (ACS)
Citation
Shepard, Scott M. et al. "Nucleoside Tetra- and Pentaphosphates Prepared Using a Tetraphosphorylation Reagent Are Potent Inhibitors of Ribonuclease A." Journal of the American Chemical Society 141, 46 (October 2019): 18400–18404 © 2019 American Chemical Society
Version
Author's final manuscript
Abstract
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.
MIT Department
Massachusetts Institute of Technology. Department of Chemistry
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DOI of Published Version
https://doi.org/10.1021/jacs.9b09760
