Determination of oxidative protein modifications using mass spectrometry.

Numerous oxidative modifications to proteins and amino acids have been identified with most susceptible, to varying degrees, of some form of oxidative modification. The consequence of oxidation on protein structure and function reveals that some of these modifications are functionally important. The discovery and accurate characterization/description of existing and new modifications requires modern instrumentation, great care, and attention to detail, especially if the modifications are present in low stoichiometric quantities or they only exist transiently. The focus of this brief review is on the use of mass spectrometry, protein chemistry, and proteomics methods and tools to identify oxidatively modified proteins and peptides along with the characterization of specific sites. Many of the specialized mass spectrometry technologies and techniques are becoming more widely available in research laboratories with mass spectrometry or proteomics facilities allowing even non-expert researchers in the field to accurately determine modifications. Illustrative examples of some approaches are provided from the author's work, collaborative research projects, and elsewhere.