Fig. 5. Application of site-specific disulfide conjugates to amine-containing drugs. (a) The disulfide conjugate is degraded by proteolysis in the lysosome and reduced by glutathione to generate a free thiol that cyclizes to generate thiirane, carbon dioxide, and the amine-containing drug. (b) Disulfide MMAE antibody conjugates were generated with (10) and without (9) a neighboring methyl group.