The focus of Volume 2 is peptides and proteins. The organization emphasizes separation techniques, preparation protocols, and fundamentals of ionic gas-phase species of biological importance. This volume is divided into four sections: experimental approaches and protocols, sequence analysis, other structural analyses, and targeted applications. The first section encompass separation procedures (e.g., 2-D gel electrophoresis), sample preparation (e.g., desalting and enzyme digestion), and instrumentation issues (e.g., high resolving power, molecular-weight determination, protein chips, and quantification). H/D exchange, analysis of membrane proteins, and bioinformatics are included. The next section on sequencing covers high energy and low energy CAD, protein identification, fundamentals of peptide fragmentation, bottom-up and top-down strategies, chemical derivatization, and post-source decay with MALDI. A section on structure analysis includes primary structure determination and issues with studying quaternary structure, protein-protein and protein-ligand complexes, disulfide analysis, phosphopeptides and phosphoproteins, selenoproteins, nitrated proteins, metal ion binding, and oxidized proteins. Additional coverage of methods for studying the biophysics of proteins is provided in Volume 6. The last chapter, Targeted Applications, focuses on neuropeptides, clinical applications, enzyme kinetics, imaging, and single-cell analysis. It covers Frontier Research on biological, biochemical, and biomedical applications of MS. It focuses on Peptides and Proteins. It is suitable for new graduate students entering the field.