The principal interest of our group is to improve technology, strategies, and micro-methods for polypeptide isolation, mass spectrometric protein identification, and mapping of modified amino acids. The program draws from conventional biochemistry as well as from the fields of chemistry and engineering. These novel tools have found widespread use in the health and life sciences as a resource for the larger research community, and for our own studies on gene expression, proteomics of the human transcriptional machinery, protein modification profiling, and serum peptide diagnostics.