273921-90-7Relevant articles and documents
Mechanism of the nitrosation of thiols and amines by oxygenated .NO solutions: The nature of the nitrosating intermediates
Goldstein,Czapski
, p. 3419 - 3425 (1996)
The nitrosation of various thiols and morpholine by oxygenated .NO solutions at physiological pH was investigated. The formation rates and the yields of the nitroso compounds were determined using the stopped-flow technique. The stoichiometry of this process has been determined, and is given by 4.NO + O2 + 2RSH/2RR'NH → 2RSNO/2RR'NNO + 2NO2- + 2H+. Kinetic studies show that the rate law is -d[O2]/dt = k1 [.NO]2[O2] with k1 = (2.54 + 0.26) x 106 M-2 s-1 and -d[.NO]/dt = 4k1 [.NO]2[O2] with 4k1 = (1.17 + 0.12) x 107 M-2 s-1, independent of the kind of substrate present. The kinetic results are identical to those obtained for the autoxidation of .NO, indicating that the rate of the autoxidation of .NO is unaffected by the presence of thiols and amines. The nitrosation by .NO takes place only in the presence of oxygen, and therefore the rate of the formation of S-nitrosothiols from thiols and oxygenated .NO solution is relatively slow in biological systems. Under physiological conditions where [.NO] 2] .NO in vivo. The rate-determining step of the nitrosation of thiols and amines by oxygenated .NO solution is the formation of ONOONO (or ONONO2 or O2NNO2), which is the precursor of .NO2 and N2O3. The stoichiometry of the nitrosation process suggests that .NO2 and/or N2O3 are the reactive species. We have demonstrated that .NO2 initiates the nitrosation process unless it is scavenged faster by .NO to form N2O3. The latter entity is also capable of directly nitrosating thiols and amines with rate constants exceeding 6 x 107 M-1 s-1.
Fluorophore-labeled S-nitrosothiols
Chen,Wen,Xian,Wang,Ramachandran,Tang,Schlegel,Mutus,Wang
, p. 6064 - 6073 (2007/10/03)
A series of fluorophore-labeled S-nitrosothiols were synthesized, and their fluorescence enhancements upon removal of the nitroso (NO) group were evaluated either by transnitrosation or by photolysis. It was shown-that, with a suitable alkyl linker, the fluorescence intensity of dansyl-labeled S-nitrosothiols could be enhanced up to 30-fold. The observed fluorescence enhancement was attributed to the intramolecular energy transfer from fluorophore to the SNO moiety. Ab initio density functional theory (DFT) calculations indicated that the "overlap" between the SNO moiety and the dansyl ring is favored because of their stabilizing interaction, which was in turn affected by both the length of the alkyl linker and the rigidity of the sulfonamide unit. In addition, one of the dansyl-labeled S-nitrosothiols was used to explore the kinetics of S-nitrosothiol/thiol transnitrosation and was evaluated as a fluorescence probe of S-nitrosothiol-bound NO transfer in human umbilical vein endothelial cells.
