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Lewis Acid Coordination Redirects S‐Nitrosothiol Signaling Output
Authors:Valiallah Hosseininasab  Alison C. McQuilken  Abolghasem Bakhoda  Jeffery A. Bertke  Qadir K. Timerghazin  Timothy H. Warren
Affiliation:Valiallah Hosseininasab,Alison C. McQuilken,Abolghasem (Gus) Bakhoda,Jeffery A. Bertke,Qadir K. Timerghazin,Timothy H. Warren
Abstract:S‐Nitrosothiols (RSNOs) serve as air‐stable reservoirs for nitric oxide in biology. While copper enzymes promote NO release from RSNOs by serving as Lewis acids for intramolecular electron‐transfer, redox‐innocent Lewis acids separate these two functions to reveal the effect of coordination on structure and reactivity. The synthetic Lewis acid B(C6F5)3 coordinates to the RSNO oxygen atom, leading to profound changes in the RSNO electronic structure and reactivity. Although RSNOs possess relatively negative reduction potentials, B(C6F5)3 coordination increases their reduction potential by over 1 V into the physiologically accessible +0.1 V vs. NHE. Outer‐sphere chemical reduction gives the Lewis acid stabilized hyponitrite dianion trans‐[LA‐O‐N=N‐O‐LA]2? [LA=B(C6F5)3], which releases N2O upon acidification. Mechanistic and computational studies support initial reduction to the [RSNO‐B(C6F5)3] radical anion, which is susceptible to N?N coupling prior to loss of RSSR.
Keywords:bioinorganic chemistry  lewis acids  nitric oxide  S-nitrosothiols
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