Global Profiling of Human Proteome Cysteine Residues via Lipoic Acid-Mediated Disulfide Exchange

Lipoic acid (LA), an endogenous small molecule, is widely
utilized
in metabolic regulation and disease intervention. While its mechanism
of action has been largely attributed to protein lipoylation, the
dynamic chemical properties of its five-membered cyclic disulfide
moiety remain underexplored. Here, we designed and synthesized alkyne-functionalized
lipoic acid-derived probes, LAN-yne and LAO-yne. Employing a chemoproteomic
strategy, we systematically mapped the covalent targets of the LAN-yne
across the cellular proteome and assessed their potential biological
functions. Quantitative proteomic analysis identified 852 probe-modified
proteins and 1,157 corresponding cysteine modification sites. This
study demonstrates that LA’s endocyclic disulfide bond can
be mimicked to mediate specific protein modification via thiol–disulfide
exchange, providing novel molecular insights and a technical platform
for investigating LA’s potential pharmacological mechanisms
and structural derivatization efforts beyond lipoylation.