ABSTRACT
Biological mass spectrometry has undergone many changes since the introduction of matrix-assisted laser desorption ionization (MALDI) by Karas and Hillenkamp [l] and electrospray ionization (ESI) by Fenn [2]. Although 252Cfplasma desorption mass spectrometry [3], laser desorption ionization [4], and fast atom bombardment mass spectrometry (FAB-MS) [5] provided many opportunities for identification and characterization of polar biologically important molecules, such experiments were difficult and the sensitivity was marginal. Conversely, the sensitivity of MALDI and ESI is excellent, low picomoles to attomoles [6], the sample preparation requirements are minimal, both molecular
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weight and structural information can be obtained, and the instrumentation requirements are modest [7,8). In this chapter we discuss requirements for obtaining high-resolution MALDI-time-of-ilight (TOP) mass spectra and show how high mass resolution can facilitate accurate mass measurements. In turn we illustrate the utility of and the need for accurate mass measurements in the analysis of peptide maps generated by enzymatic digestion of proteins.
