Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry in Peptide and Protein Analysis
Peptides and Proteins
Published Online: 15 SEP 2006
Copyright © 2000 John Wiley & Sons, Ltd. All rights reserved.
Encyclopedia of Analytical Chemistry
How to Cite
Lewis, J. K., Wei, J. and Siuzdak, G. 2006. Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry in Peptide and Protein Analysis. Encyclopedia of Analytical Chemistry. .
- Published Online: 15 SEP 2006
Matrix-assisted laser desorption/ionization mass spectrometry (MALDIMS), first introduced in 1988 by Hillenkamp and Karas, has become a widespread analytical tool for peptides, proteins and most other biomolecules. In MALDI (matrix-assisted laser desorption/ionization) analysis, the analyte is first co-crystallized with a large molar excess of a matrix compound, usually an ultraviolet (UV)-absorbing weak organic acid, after which laser radiation of this analyte–matrix mixture results in the vaporization of the matrix which carries the analyte with it. The matrix therefore plays a key role by strongly absorbing the laser light energy and causing, indirectly, the analyte to vaporize. The matrix also serves as a proton donor and receptor, acting to ionize the analyte in both positive and negative ionization modes, respectively. The efficient and directed energy transfer during a matrix-assisted laser-induced desorption event provides high ion yields of the intact analyte and allows for the measurement of compounds with high accuracy and subpicomole sensitivity. The ability to generate such accurate information can be extremely useful for protein identification and characterization. For example, a protein can often be unambiguously identified by the accurate mass analysis of its constituent peptides (produced by either chemical or enzymatic treatment of the sample). This article discusses basic MALDI concepts and instrumentation and focuses on applications in the field of peptides and proteins, specifically on the utility of MALDI in protein identification, protein structural studies, and as a clinical assay.