In Situ Generation and High Bioresistance of Trityl-based Semiquinone Methide Radicals Under Anaerobic Conditions in Cellular Systems.
Chemistry
; : e202400985, 2024 Jun 25.
Article
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| MEDLINE
| ID: mdl-38932665
ABSTRACT
Bioreduction of spin labels and polarizing agents (generally stable radicals) has been an obstacle limiting the in-cell applications of pulsed electron paramagnetic resonance (EPR) spectroscopy and dynamic nuclear polarization (DNP). In this work, we have demonstrated that two semiquinone methide radicals (OXQMâ
and CTQMâ
) can be easily produced from the trityl-based quinone methides (OXQM and CTQM) via reduction by various reducing agents including biothiols and ascorbate under anaerobic conditions. Both radicals have relatively low pKa's and exhibit EPR single line signals at physiological pH. Moreover, the bioreduction of OXQM in three cell lysates enables quantitative generation of OXQMâ
which was most likely mediated by flavoenzymes. Importantly, the resulting OXQMâ
exhibited extremely high stability in the E.coli lysate under anaerobic conditions with 76- and 14.3-fold slower decay kinetics as compared to the trityl OX063 and a gem-diethyl pyrrolidine nitroxide, respectively. Intracellular delivery of OXQM into HeLa cells was also achieved by covalent conjugation with a cell-permeable peptide as evidenced by the stable intracellular EPR signal from the OXQMâ
moiety. Owing to extremely high resistance of OXQMâ
towards bioreduction, OXQM and its derivatives show great application potential in in-cell EPR and in-cell DNP studies for various cells which can endure short-term anoxic treatments.
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01-internacional
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MEDLINE
Idioma:
En
Revista:
Chemistry
Asunto de la revista:
QUIMICA
Año:
2024
Tipo del documento:
Article