Protease Digestions on PVDF Membranes for Matrix-Assisted Laser Desorption Mass Spectrometry

Abstract

This chapter discusses the protease digestions on polyvinylidene difluoride (PVDF) membranes for matrix-assisted laser desorption mass spectrometry. Membranes can be scanned by laser desorption to locate protein. The chapter reviews the digestion of protein on the membrane and the determination of the molecular weights of digestion products. It describes experiments with proteins that have been separated by gel electrophoresis and electroblotted. Membrane absorption of protein depends strongly on the type of membrane, and the buffer used in the application of the protein to the membrane. Proteins absorbed on PVDF can be digested on the membrane, and the products found on the membrane, and characterized by laser desorption mass spectrometry. The numbered peaks correspond to expected tryptic products indicated by bracketed amino acid residue numbers. The complete sequence of lysozyme can be found in reference. Peptides for the whole sequence were not seen, but enough for positive identification from a database search were characterized.