title: Stability of the βB2B3 crystallin heterodimer to increased oxidation by radical probe and ion mobility mass spectrometry.
abstract: Ion mobility mass spectrometry was employed to study the structure of the βB2B3-crystallin heterodimer following oxidation through its increased exposure to hydroxyl radicals. The results demonstrate that the heterodimer can withstand limited oxidation through the incorporation of up to some 10 oxygen atoms per subunit protein without any appreciable change to its average collision cross section and thus conformation. These results are in accord with the oxidation levels and timescales applicable to radical probe mass spectrometry (RP-MS) based protein footprinting experiments. Following prolonged exposure, the heterodimer is increasingly degraded through cleavage of the backbone of the subunit crystallins rather than denaturation such that heterodimeric structures with altered conformations and ion mobilities were not detected. However, evidence from measurements of oxidation levels within peptide segments, suggest the presence of some aggregated structure involving C-terminal domain segments of βB3 crystallin across residues 115-126 and 152-166. The results demonstrate, for the first time, the ability of ion mobility in conjunction with RP-MS to investigate the stability of protein complexes to, and the onset of, free radical based oxidative damage that has important implications in cataractogenesis.
authors.affiliation: Graduate School of Medical Life Science, Yokohama City University, Yokohama, Japan.
authors.forename: Satoko
authors.initials: S
authors.lastname: Akashi
authors.affiliation: School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, Australia.
authors.forename: Simin D
authors.initials: SD
authors.lastname: Maleknia
authors.affiliation: Graduate School of Medical Life Science, Yokohama City University, Yokohama, Japan.
authors.forename: Kazumi
authors.initials: K
authors.lastname: Saikusa
authors.affiliation: Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Sydney, Australia. Electronic address: k.downard@sydney.edu.au.
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Downard
mesh_terms: D000818:Animals; D002417:Cattle; D019281:Dimerization; D004591:Electrophoresis, Polyacrylamide Gel; D007908:Lens, Crystalline / Q000737:chemistry*; D013058:Mass Spectrometry; D010084:Oxidation-Reduction; D055550:Protein Stability; D038206:beta-Crystallin B Chain / Q000032:analysis* / Q000737:chemistry
chemical_list: D038206:beta-Crystallin B Chain
keywords: Ion mobility; Mass spectrometry; Oxidation; Oxidative damage; Radical probe; β-Crystallin