Reagents for Rapid Reduction of Native Disulfide Bonds in Proteins

Bis(2-mercaptoethyl)sulfone (BMS) and N,N′-dimethyl-N,N′-bis(mercaptoacetyl)hydrazine (DMH) reduce native disulfide bonds in proteins at pH 7 significantly faster than does dithiothreitol (DTT). The accessible disulfide bonds in immunoglobulin and trypsinogen are reduced under nondenatoring conditions at pH 7 faster using BMS and DMH than using DTT by a factor of ∼5 to 7. The relatively less accessible disulfide bond in α-chymotrypsinogen A is also reduced faster using BMS and DMH than using DTT by a factor of 2.3. Although both BMS and DMH reduce disulfides at similar rates, we recommend BMS because it is commercially available and has superior physical characteristics and a higher reduction potential than DMH.