Sulfate radical anion as a new reagent for fast photochemical oxidation of proteins

Brian C. Gau, Hao Chen, Yun Zhang, Michael L. Gross

Research output: Contribution to journalArticlepeer-review

81 Scopus citations


The focus is to expand the original design of fast photochemical oxidation of proteins (FPOP) and introduce SO4-•, generated by 248 nm homolysis of low millimolar levels of persulfate, as a radical reactant in protein footprinting. FPOP is a chemical approach to footprinting proteins and protein complexes by "snapshot" reaction with free radicals. The radical used until now is the OH radical, and it provides a measure of residue-resolved solvent accessibility of the native protein. We show that FPOP can accommodate other reagents, increasing its versatility. The new persulfate FPOP system is a potent, nonspecific, and tunable footprinting method; 3-5 times less persulfate is needed to give the same global levels of modification as seen with OH radicals. Although solvent-exposed His and Tyr residues are more reactive with SO4-• than with OH, oxidation of apomyoglobin and calmodulin shows that OH probes smaller accessible areas than SO4-•, with the possible exception of histidine. His64, an axial ligand in the heme-binding pocket of apomyoglobin, is substantially up-labeled by SO4 -• relative to OH. Nevertheless, the kinds of modification and residue selectivity for both reagent radicals are strikingly similar. Thus, the choice of these reagents relies on the physical properties, particularly the membrane permeability, of the radical precursors.

Original languageEnglish (US)
Pages (from-to)7821-7827
Number of pages7
JournalAnalytical Chemistry
Issue number18
StatePublished - Sep 15 2010
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Analytical Chemistry


Dive into the research topics of 'Sulfate radical anion as a new reagent for fast photochemical oxidation of proteins'. Together they form a unique fingerprint.

Cite this