Determination of protein by a modified Lowry procedure in the presence of some commonly used detergents

Abstract

A wide variety of detergents has been employed to solubilize and purify membrane proteins (1,2). The interference caused by certain cationic and nonionic detergents in the Lowry procedure for protein determination (3) and its elimination by inclusion of sodium dodecyl sulfate (SDS)l has been previously described (4-7). However, only for Triton X-100 has this modification been shown definitively to be effective at concentrations of interfering detergent as high as 1% in the final reaction mixture over a range of protein concentrations (45). In this communication, we further document the applicability of a modified Lowry method to protein preparations containing high levels of nonionic and cationic detergents in common use.