Tris(2-carboxyethyl)phosphine immobilized onAgarose CL-4B Trialkylphosphines (TCEP) are highly effective agents for reducing disulfide bonds in proteins peptides and other disulfide bondcontaining molecules and are relatively non-reactive toward other functional groups. The trialkylphosphine TCEP was first described by Levison et al. as an odorless and efficient reductant of alkyl disulfides over a wide pH range. TCEP is stable in aqueous SOLUTIONons and does not undergo the rapid oxidation that often occurs with other reducing agents such as dithiotreitol (DTT) and beta-mercaptoethanol (BME 2-ME). TCEP does not interfere with commonly used sulfhydryl-reactive reagents (e.g. maleimide crosslinkers). Nevertheless many protocols require recovery of the reduced sample separate from the reducing agent. Our Tris(2-carboxyethyl)phosphine immobilized on Agarose CL-4B eliminates the need to use laborious and troublesome gel filtration methods to separate the reduced sample from the reduci