<Dd> 2 RSH ⇌ RS − SR + 2 H + 2 e </Dd> <P> A variety of oxidants participate in this reaction including oxygen and hydrogen peroxide . Such reactions are thought to proceed via sulfenic acid intermediates . In the laboratory, iodine in the presence of base is commonly employed to oxidize thiols to disulfides . Several metals, such as copper (II) and iron (III) complexes affect this reaction . Alternatively, disulfide bonds in proteins often formed by thiol - disulfide exchange: </P> <Dl> <Dd> RS − SR + R ′ SH ⇌ R ′ S − SR + RSH </Dd> </Dl> <Dd> RS − SR + R ′ SH ⇌ R ′ S − SR + RSH </Dd>

Which of these reagents is commonly used to cleave a disulfide linkages in proteins