Surfaces for interfacing protein gel electrophoresis directly with mass spectrometry

Molecular biologists and biochemists often transfer proteins separated by gel electrophoresis to membranes, such as PVDF (polyvinylidene difluoride) and nitrocellulose, for further characterization. MALDI‐MS (matrix‐assisted laser desorption/ionization mass spectrometry) can analyze proteins and peptides on a wide variety of surfaces. This review surveys the suitability of membranes and surfaces used by molecular biologists and biochemists as mass spectrometric surfaces. Matrix application considerations are reviewed. The identification of proteins by comparing the masses of peptides generated by on‐membrane digestion of proteins with theoretical digestion of database proteins is discussed. The prospects for mass spectrometric sequencing of individual peptides on membranes are presented.