ABSTRACT
High-speed, high-sensitivity peptide mapping and protein sequencing are of paramount importance to both the biotechnology and pharmaceutical industries. The speed by which aberrant forms of overexpressed, recombinant proteins are identified impacts the timeline on which the therapeutic protein makes it to market. Important to the drug discovery process in the pharmaceutical industry is the time frame for which novel therapeutic targets (e.g., receptors or enzymes) are isolated and identified. Equally important is to understand the structure/function of the therapeutic target, and this often requires knowledge and role of any posttranslational modifications. Bioanalytical chemistry has played an increasingly important role in these areas, and this is attributed principally to developments in electrospray ionization (ESI) [I ,2] and matrix-assisted laser desorption (MALDI) [3,41 mass spectrometry. A major reason for the success of these two techniques has been their ability to reach levels of sensitivity not achievable by well-established protein chemistry methods, such as gas-phase Edman sequencing. Most recently. tryptic mapping by nanospray ESI-MS [5,6] and MALDI [7] has been achieved at the subpicomole level. ESI and, more recently, delayed extraction (DE)-MALDI [8] have enabled peptide mass determinations to be made very precisely and accurately, thereby permitting rapid protein identification from protein, gene, and expressed sequence tag (EST) databases [ 9, 1 01.
