STEFs: Activated Vinylogous Protein-Reactive Electrophiles

Area of Science:

• Organic chemistry
• Chemical biology
• Bioconjugation chemistry

Background:

• Electrophilic warheads are crucial tools in chemical biology for labeling and modifying biomolecules.
• Existing methods often face limitations in selectivity or reactivity with specific functional groups.

Purpose of the Study:

• To synthesize and characterize a novel class of electrophilic warheads, semi-oxamide vinylogous thioesters (STEFs).
• To explore the reactivity and selectivity of STEFs towards biological functional groups, particularly thiols and amines.
• To demonstrate the utility of STEFs in bioconjugation applications, including their installation on complex molecular scaffolds.

Main Methods:

• Synthesis of semi-oxamide vinylogous thioesters (STEFs).
• Preparation of STEF-containing probes and their conjugation to a kinase inhibitor scaffold.
• Investigation of STEF reactivity with thiol and amine nucleophiles.
• Demonstration of STEF-mediated amine conjugation via initial thiol conjugation in peptidic and proteinogenic samples.

Main Results:

• Successful synthesis of a new class of STEFs.
• STEFs exhibit reactivity towards both thiol and amine groups.
• Amine conjugation can be facilitated by initial thiol conjugation, enhancing efficiency.
• Reactivity and selectivity of STEFs can be tuned by structural modifications.
• STEFs conjugate via a unique addition-elimination mechanism.

Conclusions:

• STEFs represent a novel class of electrophilic warheads with tunable reactivity and selectivity.
• Their ability to facilitate amine conjugation through proximal thiols offers a new strategy in bioconjugation.
• STEFs hold significant potential for broad applications in chemical biology and drug development.