Monitoring the expression and purification of recombinant proteins by MALDI-TOF mass spectrometry

Samples coming from biologic sources usually contain several contaminants t hat interfere seriously with Mass Spectrometry (MS) measurements. In this p aper we report the application of MALDI-TOF MS to monitor recombinant prote in expression and purification. The technique is based on the use of a C18 resin to clean and concentrate proteins in batch. The utility of this metho d is demonstrated for samples coming from different bacterial cultures expr essing secreted and intracellular proteins ranging from 4 to 53 kDa. MALDI- TOF MS of peptide and proteins can be accomplished directly from complex ba cterial cultures or from any purification step in a few minutes using the c onventional stainless steel sample targets, allowing for a nearly instantan eous monitoring of the nature and integrity of recombinant expression produ cts. (C) 2001 Elsevier Science Inc. Ail rights reserved.