2,2 -Dithiobis acetic acid

The 2,2 -dithiobis(acetic acid), commonly named dithioglycolic acid, used by the checker was synthesized from HSCH,COOH and SOjCl, in diethyl ether. tThe checker obtained purple crystals at this stage. 

Reagents. AVv-Fmoc-Cys(S-Trt)-OH, AG-Boc-Cys(S-Trt)-OH. reagents for peptide synthesis, Ellman s reagent 4.0 mg 5,5 -dithiobis(2-nitroben-zoic acid) in 1.0 ml of 20 mmol/liter sodium phosphate buffer pH 8.0 oxidation solution water/acetic acid/DMSO (75 5 20, v/v/v), the pH is adjusted with ammonium hydroxide to 6.0 before DMSO is added cleavage solution phenol/thioanisole/water/TIS/TFA (7.5 5 5 2.5 82.5, w/v/v/v/v). 

The method of Fan and Dasgupta (1994) relics on tlie reaction of formaldehyde with 1,3-cyclohexane-dione in acidified ammonium acetate to form the fluorescent dihydropyridine derivative in a flow injection analysis system. Formaldehyde trapped in water can be reacted with pararosaniline and sodium sulfite under mild conditions (neutral pH, room temperature equilibration) to produce a colored product that is measured at 570 nm (Petreas et al. 1986). The presence of bisulfite is an interference in this reaction so the method cannot be used to sample atmospheres that contain sulfur dioxide. In addition, the method is reported to suffer from interferences resulting from the presence of other aldehydes and phenol (Hoogenboom et al. 1987). The indirect method of Hoogenboom et al. (1987) relies on the reaction of excess bisulfite in an aqueous solution of formaldehyde with 5,5 -dithiobis(2-nitrobenzoic acid) to form a colored product, the absorbance of which is measured at 412 nm. The method reported by Naruse et al. (1995) relies on the formation of a colored product obtained by reacting the aqueous formaldehyde with acetylacetone and ammonium acetate in acetic acid. Absorbance is measured at 414 nm. 

Acetic acid, 2,2 -((dioctylstannylene) bis (thio)) bis-, diisooctyl ester. See Dioctyltin diisooctylthioglycollate Acetic acid, 2,2 -dithiobis-, diammonium salt. 

CAS 52-90-4 EINECS/ELINCS 200-158-2 FEMA 3263 INS920 E920 Synonyms L-2-Amino-3-mercaptopropanoic acid (+)-2-Amino-3-mercaptopropionic acid a-Amino-P-thiopropionic acid L-2-Amino-3-thiopropionic acid Cystein Cysteine (INCI) 3,3 -Dithiobis (2-aminopropanoic acid) P-Mercaptoalanine L-P-Mercaptoalanine Tioserine Classification A nonessential amino acid Empirical C3H7NO2S Formula HSCH2CH(NH2)COOH Properties Colorless cryst. sol. in water, ammonium hydroxide, acetic acid insol. in ether, acetone, benzene, carbon disulfide, CCU m.w. 121.16 m.p. 220 C (dec.)... 

The polymer-bound lipoic acid can be reduced by using NaBH4 (see Scheme 15-5). The reduced polymers are stable between pH 2-10 and can be reused after reduction. The resulting reduced polymer bisthiol is a potential reducing agent for disulfides. The degree of lipoyl substitution in the polymer can be found by reduction of 5,5 -dithiobis-(2-nitrobenzoic acid) (DTNB) (Ellman, 1959). The thiol content of the polymer can also be determined by reaction of the polymer with iodo[ C]acetic acid and by measurement of the uptake of radioactivity by liquid scintillation counting. 

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. ... 

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