| Summary: | 碩士 === 國立暨南國際大學 === 應用化學系 === 100 === Reversible oxidative cysteine modifications play a critical role in the redox-based signaling mechanism. Dynamic profiling oxidation state of the cysteine residues in protein such as Peroxiredoxin (Prx) presents a formidable challenge. Here, we present a novel approach to selectively isolate sulfopeptides (peptides containing cysteine sulfonic acid and sulfinic acid) from complex digests using TiO2-coated nanodiamonds (TiO2-coated NDs) prior to MS analysis. The method was applied to selectively concentrate sulfopeptides from either a highly dilute solution or a highly complex peptide mixture. This method allowed us to identify the 22 distinct cysteine oxidation status out of a total 35 present in performic-acid-oxidized BSA by MALDI-TOF MS and all the distinct cysteine oxidation status by LC-ESI-MS/MS. Finally, we applied the new approach to identify the cysteine oxidation status of hydrogen peroxide–treated Prx and BSA by LC-ESI-MS/MS. Cysteine residues were found to display in either cysteine sulfonic acid or cysteine sulfinic acid status after hydrogen peroxide treatment. Enhanced detection of low abundance sulfopeptides containing active cysteine positions (C52, C71, C83, and C173) was achieved due to the highly selective enrichment using TiO2-coate NDs.
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