Rapid profiling of induced proteins in bacteria using MALDI-TOF mass spectrometric detection of nonporous RP HPLC-separated whole cell lysates

A method for rapid profiling of water-soluble proteins from whole cell lysa tes has been developed using matrix-assisted laser desorption/ionization (M ALDI) time-of-flight mass spectrometry (TOFMS) following separation by reve rsed-phase high-performance liquid chromatography (RP HPLC). Rapid separati on of proteins from cell lysates was achieved using columns packed with C18 nonporous (NP) silica beads. Using this method, the whole cell lysate wate r-soluble proteins of E, coli were separated in under 15 min. A method usin g two columns in series at different temperatures was used in order to prov ide high loadability without loss of separation efficiency. The nonporous p acking in the columns provided for high recovery. Eluting fractions were co llected and analyzed by MALDI-TOFMS to determine the molecular weights and peptide maps of the proteins. These methods provided for the rapid screenin g and identification of proteins from E. coli where the response of E. coli to L-arabinose induction was studied. In this work, it is demonstrated tha t NP RP HPLC with MALDI-TOFMS detection may serve as a rapid means of detec ting and identifying changes in bacterial protein expression due to externa l stimuli.