Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) represents a well-accepted and reliable method for the characterization of proteins. The method has great advantages in terms of high through-put, high accuracy, and high sensitivity in measurements, which is well suited for the identification of a wide variety of proteins, such those separated by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE), and for the analysis of post-transnational modifications of a protein, which play important roles in various biological events. Taking advantages of an accumulating sequence databases, the former has been a routine task for overall profiling of proteins expressed in a cell or tissue. The latter, the analysis of post-translational modifications, is one of the most important subjects in post-genome era. We report here on the application of MALDI-MS and Edman chemistry to protein identification. The N-terminal sequence tags as well as the molecular masses of peptides revealed by MALDI-MS could be efficiently used for database searching, which increase the reliability of protein identification.
