A quantitative, high-throughput screen for protein stability

In proteomic research, it is often necessary to screen a large number of po lypeptides for the presence of stable structure. Described here is a techni que (referred to as SUPREX, stability of unpurified proteins from rates of H/D exchange) for measuring the stability of proteins in a rapid, high-thro ughput fashion. The method uses hydrogen exchange to estimate the stability of microgram quantities of unpurified protein extracts by using matrix-ass isted laser desorption/ionization MS. The stabilities of maltose binding pr otein and monomeric lambda repressor variants determined by SUPREX agree we ll with stability data obtained from conventional CD denaturation of purifi ed protein. The method also can detect the change in stability caused by th e binding of maltose to maltose binding protein. The results demonstrate th e precision of the method over a wide range of stabilities.