Figure 2.
(a) Treatment of protein with 1 at pH < 8 results in azo modification by cyclooctyne diazonium ion. Labeling can be outcompeted by addition of resorcinol or reductively removed with sodium dithionite. All samples, including controls, were treated with AlexaFluor azide in the final step prior to analysis by SDS-PAGE (b-e). (b) BSA treated with 0.2 mM 1 for 2 hours at pH 4–8. (c) BSA treated with 1 with or without excess resorcinol present. (d) BSA treated with 1 with and without a subsequent reaction with 50 mM sodium dithionite at pH 7. (e) Time point assessment of BSA treatment by 1 over the course of 6 hours at pH 7 (0.1 M PBS pH 7).