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Probing the antibody-catalyzed water-oxidation pathway at atomic resolution
Xueyong Zhu1, Paul Wentworth, Anita D Wentworth
1Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
Summary
Antibodies can generate hydrogen peroxide (H2O2) through water oxidation. Structural analysis reveals specific residue modifications in antibody fragments, pinpointing the active site and demonstrating antibody resilience to reactive oxygen species.
Area of Science:
- Biochemistry
- Structural Biology
- Immunology
Background:
- Antibodies can catalyze the generation of hydrogen peroxide (H2O2) from singlet dioxygen and water.
- This process involves postulated intermediates like dihydrogen trioxide (H2O3).
- Understanding the antibody's structural response to these reactive species is crucial.
Purpose of the Study:
- To elucidate the chemical consequences of reactive intermediates on antibody structure.
- To identify the specific location on the antibody where water oxidation occurs.
- To provide structural evidence for antibody-catalyzed water oxidation.
Main Methods:
- Determination of nine different crystal structures of murine antibody antigen-binding fragments (Fabs).
- UV-irradiation of Fabs 4C6 and 13G5.
- Crystal structure analyses to identify oxidative modifications.
Main Results:
- Structural evidence for oxidative modifications to specific antibody residues was found.
- Complex oxidative modifications occurred at tryptophan L163 in both Fabs.
- Hydroxylation of glutamine H6 was observed in Fab 4C6.
Conclusions:
- The findings support the hypothesis that the active site for water oxidation is in the interfacial region of variable and constant domains.
- Specific residue modifications provide insights into the antibody-catalyzed water oxidation mechanism.
- Antibodies demonstrate general resistance to oxidation by reactive oxygen species generated during this process.