5-Thio-2-nitrobenzoate

Ellman s Reagent Sulfhydryl Disulfide Bond 5-Thio-2-nitrobenzoic... 

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-... 

Probably the most frequently used spectrophotometric method to detect thiol groups, both for non-protein and protein sulphydryl groups involves the use of Ellman s reagent (Scheme 7.5). 5,5 -Dithiobis(2-nitrobenzoic acid), (DTNB) (Ellman 1959) undergoes disulphide exchange with thiol groups and the formation of 5-thio-2-nitrobenzoate anion (TNB) (Scheme 7.6). 

Tubular membrane tension/mucosal DNA thermal melting point midpoint of thermal denaturation curve Transmembrane Trimethylamine oxide Transmembrane domain Trimethylsilyl thimersol Tobacco mosaic virus Treose nucleic acid 5-thio-2-nitrobenzoate... 

Pyridyl disulfides, 5-thio-2-nitrobenzoic (TNB) acid Mixed disulfide (14, 147)... 

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

The colorimetric method is based on the hydrolysis of the substrate acetylthiocholine to acetate and thiocholine as performed by the cholinesterase. Thiocholine is then reacted with 5,5 -dithiobis(2-nitrobenzoic acid) (DTNB) to form a yellow anion (5-thio-2-nitrobenzoate). The latter is quantitated by spectrometric analysis at 405 nm, with the concentration being proportional to the cholinesterase activity in the given sample. Also for a few days postmortem the cholinesterase activity in different tissues is measurable. ... 

A procedure for identifying certain cholinesterase variants was proposed by Dietz et al. (D15). After a period during which comments and discussion were offered by others working in the field, the method was published in Selected Methods of Clinical Chemistry (D16). This method is based upon the Ellman reaction (ElO), which was used by Ellman et al. (Ell) for the assay of acetylcholinesterase, and by Garry and Routh (G9) for the assay of serum cholinesterase. In these assay procedures, a thiocholine ester is used as the substrate. The thiocholine produced upon hydrolysis reacts with 5,5 -dithiobis(2-nitrobenzoic acid) (DTNB) to yield 5-thio-2-nitrobenzoate anion and other products. The rate of the reaction may be determined by measuring the rate at which... 

A radiometric and a spectrometric assay have been developed to measure PhaC activity. The radiometric assay measures the incorporation of isotope-labeled hydroxyacyl moieties into the polyester, which is present from the beginning as primer [17]. [3-14]ft-(-)-3-hydroxybutyryl-CoA or [3H]-P,S-3-hydroxybutyryl-CoA or in principle any other CoA thioester of a radioactively-labeled hydroxyacyl moiety could be used as substrate. Only the radioactivity that is really incorporated into the insoluble polyester is measured. The time course of the assay, the need to synthesize the substrates and the high costs make the assay very inconvenient and it is hardly used anymore. A more convenient assay is the spectrometric assay which measures the release of coenzyme A during the polymerization reaction in presence of Ellmann s reagent 5,5 -dithiobis-(2-nitrobenzoic acid) (DTNB) yielding 5 -thio(2-nitrobenzoate) that absorbs at about 412 nm [16], Here, the enzyme activity is measured directly without delay. However, it is not the formation of the polymeric product that is measured, but the release of coenzyme A, which can also be due to the hydrolytic cleavage of the substrate by another enzyme that does not have any PhaC activity, like a thioesterase. Nevertheless, this assay is now most frequently used due to its convenience. 

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... 

Metallothionein was isolated from horse kidney tissue by adaptation of standard methods and purified by Sephadex G-75 and DEAE-Sephadex chromotography ( ). The reactions of purified MT with various amounts of Na2AuTM were conducted by incubating samples at 4 C in Tris-HC buffer, pH 7.8 for 2 hours and fractionating the mixture on Sephadex G-50. Fractions were analyzed for free and bound metals. The kinetics of reaction between MT and DTNB was studied by mixing DTNB and MT under N, in anaerobic cuvettes containing 10 mm Tris-HCl/O.lM KCl, pH 8.6 at 25 C. The reaction was followed by the appearance of 5-thio-2-nitrobenzoate which absorbs at 412 nm. Pseudo-first order conditions were maintained with excess (10 to 100 fold) DTNB. 

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