Figure 2.

Cleavable linker design process. (a) Acid-cleavable linker 1 inspired the design of oxidatively cleavable linker 4. (b) Cyclic voltammograms of alcohols 2 and 3. Pt disc working electrode (2 mm diameter), platinum wire counter electrode, and Ag/AgCl reference electrode. Induction period of 3 s at initial voltage prior to sweep at 10 mV/s. Alcohol (20 mM) in 60 vol % 0.5 M potassium phosphate buffer, pH 7.4, 40 vol % acetonitrile. Oxidation of 2 was observed to be irreversible with E_1/2 = +1.18 V. A substantial increase in current is observed, suggesting catalytic oxidation of water. Oxidation of 3 was observed to be reversible with E_1/2 = +0.81 V. (c) Structure of conjugate 5.