TCEP

Tris(2-carboxyethyl)phosphine, commonly abbreviated as TCEP, is a water-soluble phosphine reducing agent used to break disulfide bonds in proteins and nucleic acids. It is a non-thiol reductant that is widely favored for laboratory applications because it is odorless and more stable in aqueous solutions than traditional thiol-based reagents such as dithiothreitol (DTT) or beta-mercaptoethanol.

TCEP is typically available as the hydrochloride salt (TCEP·HCl) or as a free base. It is notably stable over a broad pH range and at room temperature, which makes it convenient for use in various buffers and protocols. Unlike thiol reagents, it does not introduce free thiol groups into samples, reducing the risk of unwanted disulfide exchange or cross-reactivity in downstream analyses.

In practical use, TCEP is effective at modest concentrations (often 0.1 to 5 mM) and is compatible with many standard biochemical workflows, including SDS-PAGE sample preparation, enzyme assays, and labelings that are sensitive to thiols. It can remain active in the presence of detergents and salts common to biochemical buffers, and it is frequently a preferred choice when maintaining protein activity or avoiding odor is important.

Safety and handling considerations include typical chemical safety practices: use PPE, avoid inhalation or contact with skin and eyes, and store in a cool, dry place. TCEP solutions should be disposed of according to local regulations for chemical waste.

See also: dithiothreitol, beta-mercaptoethanol, reducing agents.