5-Thio-2-nitrobenzoic acid

Ellman s reagent, 5,5 -dithio-bis-(2-nitrobenzoic acid), or DTNB, is a compound useful for the quantitative determination of sulfhydryls in solution (Ellman, 1958,1959). The disulfide of Ellman s reagent readily undergoes disulfide exchange with a free sulfhydryl to form a mixed disulfide and release of one molecule of the chromogenic substance 5-sulfido-2-nitrobenzoate, also called 5-thio-2-nitrobenzoic acid (TNB). The intense yellow color produced by the TNB anion can be measured by its absor-... 

The stability of the initially generated /V-chloroamide remains so far controversial. On the one hand, TV-chloroamides are assumed to be "transient products" [258], while on the other hand, they were described to represent "long-lived species" [230]. This obvious discrepancy may result from two different reasons. First, this might result from the different experimental methods that were used Schiller et al. [258] uses NMR spectroscopy, while Rees et al. [230] applies the 5-thio-2-nitrobenzoic acid (TNB) assay [261] to monitor the stability of the TV-chloroamides. It is not yet clear, whether that... 

RA rheumatoid arthritis, RNS reactive nitrogen species, ROS reactive oxygen species, SF synovial fluid, SOD superoxide dismutase, SPAMl sperm adhesion molecule-1, TGF- transforming growth factor beta, TNB 5-thio-2-nitrobenzoic acid, TNF-a tumor necrosis factor alpha, UDP uridine diphosphate... 

The kinetics and mechanism of the reaction of HOSCN/OSCN with 5-thio-2-nitrobenzoic acid (TNB) have been investigated as a function of pH (77). The reaction is first order with respect to [OSCN ] and first order with respect to [TNB]. The observed bell-shaped profile in the 2.5conjugate acid with a conjugate base. Assuming that the acid/base equilibria are rapid, the mechanism of Eqs. (52)-(55) was proposed (where TNB is the carboxylate anion, TNB includes deprotonation of the thiol, and DTNB is the disulfide) ... 

TV - A -(6-Aminohexyl)-carbamoylmethyl ]-N ADH N -( A -(6-Aminohexyl)-carbamoylmethyl]-5-(5-thio-2-nitrobenzoic acid)coenzyme A... 

Nekrassova et al. [13] have also studied the electrochemical oxidation of 5-thio-2-nitrobenzoic acid (TNBA) at a BDD electrode for the indirect detection of cysteine, homocysteine and glutathione. The reaction was shown to proceed via a CEC reaction process at lower pH, in which the thiol moiety of the TNBA species must undergo deprotonation before oxidation. These authors also reported that 5,5-dithiobis(2-nitrobenzoic acid) (DTNB) can be used to develop the total thiol detection methodology using chronoamperometry with BDD electrodes. The detection limits of cysteine, homocysteine and glutathione were found to be 5.7 pM, 4.4 pM and 5.8 pM respectively. 

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