Liquid chromatography (LC) can be combined with matrix-assisted laser-desorption ionization (MALDI) mass-spectrometry (MS)
by using automated off-line fraction collection of eluates onto a MALDI plate. Commercial tandem MS systems are available
for generating product ion spectra of MALDI-produced peptide ions. The MALDI MS/MS spectra can be searched against a proteome
database for protein identification. In this chapter, a protocol of sequential solubilization and digestion of membrane proteins
involving methanol- and SDS-assisted trypsin digestion and microwave-assisted acid hydrolysis is presented. The process of
LC eluate deposition onto a MALDI plate along with practical considerations for achieving optimal performance of eluate deposition
is described. Issues related to MALDI MS and MS/MS spectral acquisition are discussed. Database searching and manual inspection
of MS/MS spectra of singly charged MALDI-produced peptide ions for positive protein identification are also addressed.
Key Words Trypsin digestion - microwave-assisted acid hydrolysis - LC-MALDI MS and MS/MS