Dithiothreitol (DTT) is a small molecule organic reducing agent with chemical formula of c4h10o2s2. It is a linear molecule in the reduced state and becomes a six membered ring structure containing disulfide bonds after being oxidized. The name dithiothreitol is derived from threitol (a four carbon monosaccharide). The isomer of DTT is dithiocarbitol (DTE), which is the C3 epimer of DTT.
Chinese Name: dithiothreitol
Foreign name: dithiothreitol
Alias: 1,4-dithiothreitol
Chemical formula: c4h10o2s2
Molecular weight: 154.251cas
Registration No.: 3483-12-3
Boiling point: 364.45 ℃
Density: 1.303 g / cm ³
Appearance: white solid
Flash point: 174.22 ℃
brief introduction
IUPAC Name: (2S, 3S) - 1,4-bis-sulfanylbutane-2,3-diol
Alias: 1,4-dithiothreitol, dithiothreitol, Cleland reagent
distinguish
CAS No.: 3483-12-3, 27565-41-9
PubChem：446094SMILES SC[C@@H](O)[ C@H ](O)CS
nature
Chemical formula: c4h10o2s2 [1-2]
Molar mass: 154.253 g · mol − 1
Appearance: white solid
Melting point: 42-43 ° C
Boiling point: 125-130 ° C (at 2 mmHg pressure)
Solubility in water: soluble
Unless otherwise specified, all data are from 25 ° C and 100KPA.
Reducibility
DTT is a strong reductant, and its reducibility is largely due to the conformational stability of its oxidized six membered ring (containing disulfide bond). Its redox potential was -0.33 volts at pH 7. The reduction of a typical disulfide bond by dithiothreitol is composed of two consecutive mercapto disulfide bond exchange reactions:
Among them, the intermediate state formed by the first reaction is very unstable, because the second sulfhydryl group on DTT tends to connect with the oxidized sulfur atom, so that the intermediate state is quickly converted into the cyclic oxidation structure of DTT, thus completing the reduction of disulfide bond.
The reducing power of DTT is affected by the pH value, and it can only play a reducing role when the pH value is greater than 7. This is because only the deprotonated thiolate anion (- s –) is reactive, while the thiol (- SH) is not; And the pKa of the thiol group is generally & # x2dc; 8.3.
application
One of the uses of DTT is as a reducing agent and deprotective agent for thiolated DNA. Thiolated DNA terminal sulfur atoms tend to form dimers in solution, especially in the presence of oxygen. This dimerization greatly reduces the efficiency of some coupling reaction experiments (such as DNA fixation in biosensors); The dimerization of DNA can be reduced by adding DTT to the DNA solution and removing it after a period of reaction.
DTT is also often used to reduce disulfide bonds in proteins, and can be used to prevent intramolecular or intermolecular disulfide bonds formed between cysteines in proteins. However, DTT is often unable to reduce the disulfide bonds embedded in the protein structure (inaccessible to the solvent), and the reduction of such disulfide bonds often requires denaturation of the protein (high temperature heating or addition of denaturant, such as 6m guanidine hydrochloride, 8m urea or 1% SDS). On the contrary, according to the different reduction speed of disulfide bond in the presence of DTT, the depth of its embedding can be judged.
Product features:
The stability of DTT is poor because it is easily oxidized by air; But cryopreservation or treatment in inert gas can prolong its service life. Due to the low nucleophilicity of the protonated sulfur, the effective reducibility of DTT decreases with the decrease of pH value; Tris (2-carboxymethyl) phosphate HCl (TCEP hydrochloride) can be used as a substitute for DTT under low pH conditions, and it is more stable than DTT.