Thionitrite and Perthionitrite in NO Signaling at Zinc
Valiallah Hosseininasab, Jeffery A. Bertke, Timothy H. Warren
Abstract
Abstract NO and H 2 S serve as signaling molecules in biology with intertwined reactivity. HSNO and HSSNO with their conjugate bases − SNO and − SSNO form in the reaction of H 2 S with NO as well as S‐nitrosothiols (RSNO) and nitrite (NO 2 − ) that serve as NO reservoirs. While HSNO and HSSNO are elusive, their conjugate bases form isolable zinc complexes Ph,Me TpZn(SNO) and Ph,Me TpZn(SSNO) supported by tris(pyrazolyl)borate ligands. Reaction of Na(15‐C‐5)SSNO with Ph,Me TpZn(ClO 4 ) provides Ph,Me TpZn(SSNO) that undergoes S‐atom removal by PEt 3 to give Ph,Me TpZn(SNO) and S=PEt 3 . Unexpectedly stable at room temperature, these Zn‐SNO and Zn‐SSNO complexes release NO upon heating. Ph,Me TpZn(SNO) and Ph,Me TpZn(SSNO) quickly react with acidic thiols such as C 6 F 5 SH to form N 2 O and NO, respectively. Increasing the thiol basicity in p‐substituted aromatic thiols 4−X ArSH in the reaction with Ph,Me TpZn(SNO) turns on competing S‐nitrosation to form Ph,Me TpZn‐SH and RSNO, the latter a known precursor for NO.