Dithiothreitol (DTT) is the common name for a small-molecule redox reagent also known as Cleland's reagent. DTT's formula is C₄H₁₀O₂S₂ and the chemical structure of one of its enantiomers in its reduced form is shown at the right; its oxidized form is a disulfide bonded 6-membered ring (shown below). The reagent is commonly used in its racemic form, as both enantiomers are reactive. Its name derives from the four-carbon sugar, threose. DTT has an epimeric ('sister') compound, dithioerythritol (DTE).