Development of methods for the charge-derivatization of peptides in polyacrylamide gels and membranes for their direct analysis using matrix-assisted laser desorption-ionization mass spectrometry

Approaches are being developed for the interfacing of matrix-assisted laser desorption-ionization (MALDI) mass spectrometry with polyacrylamide gel electrophoresis, in which laser-irradiated samples desorb directly from a gel, or from a membrane on which gel-separated polypeptides have been transferred. Whether one-or two-dimensional electrophoretic separations have been performed, preparations for the MALDI experiment which follow must optimize detection of the analytes present and the generation of structural information. Procedures have been developed for forming charged derivatives of peptides in solution. When subjected to MALDI analysis, these charged derivatives produce ions in some cases where the underivatized peptide would not yield a response. The ions fragment following acceleration and yield informative and simple post-source decay (PSD) spectra. The development of approaches to interfacing this chemistry with MALDI directly from gels and membranes is presented here. (C) 1997 Elsevier Science B.V.