| With sufficient separation of complex protein mixtures, MALDI MS is an important analytical tool for detection of proteins. In this work, two important areas of proteomics research were studied: the detection of hydrophobic membrane proteins and cancer proteomics. Our work is the first demonstration of using sequential CNBr/trypsin digestion for the analysis of low amounts of hydrophobic membrane proteins in-gels. Peptide mass mapping using MALDI MS and sequence information by MALDI MS/MS enabled the confirmation of protein identification. The inherent advantages and limitations of the mass spectrometric technique are discussed and the usefulness of complementary techniques, such as ESI-MS with on-line MS/MS capabilities, is demonstrated. For the cancer proteomics work, separation techniques of polyacrylamide gel electrophoresis and liquid chromatography were combined with MALDI MS. The direct comparisons of protein expression and detection of the differentially expressed proteins in squamous carcinoma cells are demonstrated to be well suited for biomarker discovery. |
