TCEP (tris(2-carboxyethyl)phosphine) is a strong reducing agent. Compared to dithiothreitol (DTT) and beta-mercaptoethanol, TCEP has the advantages of being odorless, a more powerful reducing agent, an irreversible reducing agent, more hydrophilic, and more resistant to oxidation in air. It is soluble in water and stable at neutral pH. It does not reduce metals used in immobilized metal affinity chromatography such as Ni-NTA resin. TCEP is particularly useful when labeling cysteine residues with maleimides.
