Disulfidit

Disulfidit, known in English as disulfides, are a class of organosulfur compounds that contain a disulfide bond, an S–S linkage connecting two sulfur atoms. In most disulfides the two sulfur atoms are bound to carbon substituents: R–S–S–R'. The S–S bond is relatively weak compared with many carbon–carbon bonds and is susceptible to oxidation and reduction, making disulfides versatile in chemistry and biology.

Formation and interconversion: Disulfides commonly form by oxidation of thiols (R–SH) to give R–S–S–R'. In living systems, disulfide bonds form in proteins largely in oxidizing environments such as the endoplasmic reticulum, catalyzed by enzymes like protein disulfide isomerase, and contribute to protein folding and stability. In reducing environments, disulfide bonds can be cleaved to yield thiols.

Reactions: Disulfide bonds can undergo thiol–disulfide exchange with other thiols, generating new disulfides and reshuffling disulfide patterns. They can be reduced by reagents such as dithiothreitol (DTT), beta-mercaptoethanol, or cellular reducing systems like glutathione, enabling redox regulation of protein structure.

Occurrence and significance: The amino acid cystine is formed from two cysteine residues and is common in extracellular proteins; many enzymes and antibodies rely on disulfide bonds to maintain structure. Disulfides also appear in small-molecule reagents and in polymer chemistry for redox-responsive materials.

Uses and examples: Simple disulfides such as diphenyl disulfide and diethyl disulfide are used in synthesis and studies of redox chemistry. In organic synthesis, disulfides can serve as protecting groups for thiols and as building blocks for disulfide-exchange chemistry.