AChE activity self-breathing control mechanisms regulated by H2Sn and GSH: Persulfidation and glutathionylation on sulfhydryl after disulfide bonds cleavage.

Hydrogen sulfide (H2S), or dihydrogen sulfane (H2Sn), acts as a signal molecule through the beneficial mechanism of persulfidation, known as the post-translational transformation of cysteine residues to persulfides. We previously reported that Glutathione (GSH) could regulate enzyme activity through S-desulfurization or glutathionylation of residues to generate protein-SG or protein-SSG, releasing H2S. However, little is known about the mechanisms by which H2Sn and GSH affect the disulfide bonds. In this study, we provide direct evidences that H2Sn and GSH modify the sulfhydryl group on Cys272, which forms disulfide bonds in acetylcholinesterase (AChE), to generate Cys-SSH and Cys-SSG, respectively. Glutathionylation of disulfide is a two-step reaction based on nucleophilic substitution, in which the first CS bond is broken, then the SS bond is broken to release H2S. H2Sn and GSH controlled self-breathing motion in enzyme catalysis by disconnecting specific disulfide bonds and modifying cysteine residues, thereby regulating AChE activity. Here, we elucidated H2Sn and GSH mechanisms on disulfide in the AChE system and proposed a self-breathing control theory induced by H2Sn and GSH. These theoretical findings shed light on the biological functions of H2Sn and GSH on sulfhydryl and disulfide bonds and enrich the theory of enzyme activity regulation.