J. L. Beauchamp
Charles and Mary Ferkel Professor of Chemistry
California Institute of Technology
"Reaction of Carbon Centered Radicals with Specific Amino Acids in Peptides and Proteins: Implications for the Biochemical Effects of Oxidative Stress"
Abstract:
Free radicals play an important role in biochemical processes ranging from enzyme catalysis to protein degradation. The model peptides AARAAAXAA, where X is one of the 20 common amino acids, have been derivatized to incorporate an acetyl radical at the N terminus. Using electrospray ionization and ion trap mass spectrometry, the singly charged peptide is isolated in the gas phase and subjected to collisional activation. Both alanine and arginine have low reactivity with free radicals, making it possible to observe specific reactions of the acetyl radical with the varied amino acid X. Observed reactions typically include backbone cleavage and/or side chain loss. The 20 common amino acids can be grouped according to their patterns of reactivity. These patterns will be discussed, along with their implications for the biochemical effects of oxidative stress and for the use of free radical reagents for protein sequencing (J. Am. Chem. Soc. 2005, 127, 12436-12437).
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