Hydroxyl-Radical Reaction Pathways for the Fast Photochemical Oxidation of Proteins Platform As Revealed by 18O Isotopic Labeling

Anal Chem. 2019 Jul 16;91(14):9238-9245. doi: 10.1021/acs.analchem.9b02134. Epub 2019 Jun 26.

Abstract

Fast photochemical oxidation of protein (FPOP) has become an important mass spectrometry-based protein footprinting approach. Although the hydroxyl radical (OH) generated by photolysis of hydrogen peroxide (H2O2) is most commonly used, the pathways for its reaction with amino-acid side chains remain unclear. Here, we report a systematic study of OH oxidative modification of 13 amino acid residues by using 18O isotopic labeling. The results differentiate three classes of residues on the basis of their oxygen uptake preference toward different oxygen sources. Histidine, arginine, tyrosine, and phenylalanine residues preferentially take oxygen from H2O2. Methionine residues competitively take oxygen from H2O2 and dissolved oxygen (O2), whereas the remaining residues take oxygen exclusively from O2. Results reported in this work deepen the understanding of OH labeling pathway on a FPOP platform, opening new possibilities for tailoring FPOP conditions in addressing many biological questions in a profound way.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Amino Acids / chemistry
  • Animals
  • Cattle
  • Hydrogen Peroxide / chemistry
  • Hydrogen Peroxide / radiation effects
  • Hydroxyl Radical / chemistry
  • Isotope Labeling / methods*
  • Oxidation-Reduction
  • Oxygen / chemistry
  • Oxygen / radiation effects
  • Oxygen Isotopes / chemistry*
  • Peptide Fragments / chemistry*
  • Photolysis
  • Protein Footprinting / methods
  • Serum Albumin, Bovine / chemistry*
  • Ultraviolet Rays

Substances

  • Amino Acids
  • Oxygen Isotopes
  • Oxygen-18
  • Peptide Fragments
  • Serum Albumin, Bovine
  • Hydroxyl Radical
  • Hydrogen Peroxide
  • Oxygen