Tunable heteroaromatic azoline thioethers (HATs) for cysteine profiling

Abstract

Here we report a new series of hydrolytically stable chemotype Heteroaromatic Azoline Thioethers (HAT) to achieve highly selective, rapid, and efficient covalent labeling of cysteine under physiological conditions. Although the...

Chemical modification of proteins – challenges and trends at the start of the 2020s

“…The reactivities of the former can be tuned by varying the number of fluorine atoms and electron-withdrawing groups, 86 whereas the latter can be tuned by varying the structure and number of heteroatoms of the aryl moiety. 87,88…”

Fast Cysteine Bioconjugation Chemistry

“…[28] 10 folds of acceleration were observed when comparing sulfone MSBT with heteroaromatic azole thioether (HAT) developed by Raj and co-workers. [29] Benefiting from their rapid kinetics and high reactivity, these cysteine conjugations with activated heteroaromatic compounds can greatly enhance the detection limit for in-cell profiling, revealing greater number of active thiol species than classical iodoacetamide chemistry. [14] Alternatively, electron-deficient heteroaromatic compounds could conjugate with cysteine through a cine-substitution mechanism, where the thiol substitution happens at the adjacent carbon of leaving group.…”

“…More electronegative oxygen or nitrogen atom substituents in heterocycle cores also enhance the reactivity compared to benzothiazole 19 c , such as benzoxazole 19 l ( k 2 =845 M −1 s −1 ,1690 folds), and tetrazole 19 h ( k 2 =6.0 M −1 s −1 , 12 folds) [28] . 10 folds of acceleration were observed when comparing sulfone MSBT with heteroaromatic azole thioether (HAT) developed by Raj and co‐workers [29] . Benefiting from their rapid kinetics and high reactivity, these cysteine conjugations with activated heteroaromatic compounds can greatly enhance the detection limit for in‐cell profiling, revealing greater number of active thiol species than classical iodoacetamide chemistry [14] …”

Rapid Electrophilic Cysteine Arylation with Pyridinium Salts

“…In addition, although the incorporation of hydrophobic tags, such as polyfluorinated arenes, can potentially improve the pharmacokinetics of the resulting conjugate, in other instances, it is desirable to label proteins with hydrophilic moieties that do not significantly perturb native structure and possibly preserve wild-type protein–protein interactions . Overall, these challenges highlight the current limitations of cysteine arylation chemistry and reflect the increasing need for rapid, hydrophilic tools allowing for bioconjugation at low micromolar concentrations within hours. − …”