25. Retro Diels–Alder Fragmentation of Fulvene–Maleimide Bioconjugates for Mass Spectrometric Detection of Biomolecules

Abstract:

Diels–Alder chemistry is a well-explored avenue for the synthesis of bioactive materials; however, its potential applications have recently expanded following the development of reactions that can be performed in buffered aqueous environments at low temperatures, including fulvene–maleimide [4 + 2] cycloadditions. In this study, we synthesized two novel amine-reactive fulvene linkers to demonstrate the application of this chemistry for generating mass spectrometry-cleavable labels (“mass tags”), which can be used for the labeling and detection of proteins. Successful conjugation of these linkers to maleimide-labeled peptides was observed at low temperatures in phosphate-buffered saline, allowing the non-destructive modification of proteins with such mass tags. The labile nature of fulvene–maleimide adducts in the gas phase also makes them suitable for both matrix-assisted laser desorption/ionization (MALDI) and electrospray ionization (ESI) mass spectrometric analysis. Unlike previous examples of MALDI mass tags, we show that fulvene–maleimide cycloaddition adducts fragment predictably upon gas-phase activation without the need for bulky photocleavable groups. Further exploration of this chemistry could therefore lead to new approaches for mass spectrometry-based bioassays.

Stevens, K.; Platts, K.; O’Brien-Simpson; N. M.; Li, W.; Blencowe, A.; Trim, P. J.; Pukala, T.* (2021), Fulvene-maleimide bioconjugates for mass spectrometric detection of biomolecules, Anal. Chem. 2021, 93, 36, 12204–12212, DOI: 10.1021/acs.analchem.1c00193