55dithiobis2nitrobenzoic

55Dithiobis(2-nitrobenzoic acid), commonly abbreviated as DTNB or Ellman's reagent, is a chemical compound widely used in biochemical research and analytical chemistry. Its systematic name is 2,2′-dithiobis(5-nitrobenzoic acid), reflecting its structure, which consists of two nitrobenzoic acid units linked by a disulfide bond. The compound is characterized by its yellow color and high solubility in organic solvents, making it useful for various applications.

DTNB is primarily recognized for its role in the quantification of thiols, such as cysteine and glutathione, through its reaction with reduced thiols. When DTNB reacts with a thiol group, it forms a mixed disulfide and a colored anion (2-nitro-5-thiobenzoate), which absorbs strongly at 412 nm. This colorimetric change allows for the sensitive detection and measurement of thiol concentrations using spectrophotometry. The reaction is highly specific and reversible, enabling its use in both qualitative and quantitative assays.

In addition to its use in thiol detection, DTNB serves as a reducing agent and is employed in the determination of disulfide bonds in proteins and other biological macromolecules. It can also be utilized in the study of enzymatic activities, particularly those involving thiol-dependent enzymes. The reagent’s stability and ease of handling make it a preferred choice for many laboratories.

DTNB was first described by the American biochemist Richard Ellman in 1959, and since then, it has become a standard tool in biochemical analysis. Its widespread use underscores its importance in fields such as pharmacology, toxicology, and protein chemistry. The compound is typically available in powder or solution form, with high purity standards ensuring reliable experimental results.