ABTS
IUPAC name	2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid)
Identifiers
CAS number	28752-68-3
SMILES	CCN1/C(Sc2cc(ccc12)S(O)(=O)=O)=N/N=C/3Sc4cc(ccc4N3CC)S(O)(=O)=O
Properties
Molecular formula	C18H18N4O6S4
Molar mass	514.62 g/mol
Hazards
R-phrases	R36 R37 R38
S-phrases	S26-S36
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

In biochemistry, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) or ABTS is chemical compound used to observe the reaction kinetics of specific enzymes. A common use for it is in the enzyme-linked immunosorbent assay (ELISA) to detect for binding of molecules to each other.

[edit] Uses

It is commonly used as a substrate with hydrogen peroxide for a peroxidase enzyme or alone with a laccase enzyme. Its use allows the reaction kinetics of peroxidases themselves to be followed. In this way it also can be used to indirectly follow the reaction kinetics of any hydrogen peroxide-producing enzyme, or to simply quantify the amount of hydrogen peroxide in a sample.

This compound is chosen because the enzyme facilitates the reaction with hydrogen peroxide, turning it into a green and soluble end-product. Its new absorbance maximum of 420 nm light can easily be followed with a spectrophotometer, a common laboratory instrument. It is sometimes used as part of a glucose estimating reagent when finding glucose concentrations of solutions such as blood serum.

ABTS is also frequently used by the food industry and agricultural researchers to measure the antioxidant capacities of foods.^[1] In this assay, ABTS is converted to its radical cation by addition of sodium persulfate. This radical cation is blue in color and absorbs light at 734 nm.^[2] The ABTS radical cation is reactive towards most antioxidants including phenolics, thiols and Vitamin C.^[3] During this reaction, the blue ABTS radical cation is converted back to its colorless neutral form. The reaction may be monitored spectrophotometrically. This assay is often referred to as the Trolox equivalent antioxidant capacity (TEAC) assay. The reactivity of the various antioxidants tested are compared to that of Trolox, which is a vitamin E analog.

[edit] References

1. ^ Huang, D.; Ou, B.; Prior, R. L. The chemistry behind antioxidant assays. J. Agric. Food Chem. 2005, 53, 1841-56
2. ^ Re, R.; Pellegrini, N.; Pannala, A.; Yang, M.; Rice-Evans, C. Antioxidant activity applying an improved ABTS radical cation decolorization assay. Free Radical Biol. Med. 1999, 26, 1231-1237
3. ^ Walker, R.; Everette, J. Comparative reaction rates of various antioxidants with ABTS radical cation. J. Agric. Food Chem. 2009, 57, 1156-1161

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