DL-Dithiothreitol (DTT) - Molecular biology grade

Dithiothreitol (DTT) is an isomer (epimer) of dithioerythritol (DTE). In principle, DTT can be exchanged for DTE or DTE for DTT, of which both are excellent reducing substances.

Dithiothreitol (DTT), like ß-mercaptoethanol, is used as a reducing agent to increase the stability of proteins as protection against the undesired oxidation of cysteine residues. Proteins can oxidize during gel electrophoresis. This results in broader bands (reduced resolution) and non-reproducible mobility (incorrect assessment of the molecular weight).

DTT can be used in practically all experiments in a three to four times lower molar concentration than ß-mercaptoethanol. It is less toxic, less odor intensive and does not form mixed disulfides like ß-mercaptoethanol. DTT is water-soluble and is usually prepared as a 1M stock solution. This solution should be stored in aliquots at -20°C and protected from heat while working. A sufficient amount should be added to the solutions in the experiment, since it oxidizes relatively quickly in air.

The working concentration is between 0.1 and 1mM, but must be increased to up to 5mM, for example in the production of plant extracts, or up to 10mM in the 'large scale in situ isolation' of proteins during fermentation. While DTT has a pK value of 8.3 and 9.5, the pK is 9.0 and 9.9 for DTE. Since both compounds show their reducing properties only in the ionized state, their reducing effect is greatest in the pH range 7.0 - 9.5. In the lower pH range, DTT is more active than DTE. The reducing effect can be stopped by acidification (e.g. acetic acid to pH3).