Thiolýza

Thiolýza is the chemical process by which a bond is broken under the action of a thiol (R–SH) or its conjugate base, a thiolate (RS−). In organic chemistry, thiolýza refers to nucleophilic substitution or exchange reactions in which a thiolate attacks a substrate to cleave a bond and form a new thioester or thioether. Common substrates include thioesters, esters, and acyl halides, where thiols promote cleavage or exchange of the acyl group. A typical outcome is the formation of a new thioester or the release of an alcohol or halide, depending on the substrate and conditions. Thiolýza is a key step in trans-thioesterification processes such as native chemical ligation in peptide synthesis, where a cysteine-containing peptide reacts with a peptide thioester to form a longer polypeptide, followed by an acyl shift to yield a native amide bond.

In biochemistry, thiolýza often refers to thiol-disulfide exchange and the reduction of disulfide bonds. Thiol-containing molecules like cysteine, glutathione, beta-mercaptoethanol, or dithiothreitol can cleave disulfide bonds, altering protein structure and activity. This mechanism underlies many cellular redox processes and is exploited in laboratory protein purification and analysis.

Related topics include disulfide reduction, thiol-disulfide exchange, and native chemical ligation.