Figure 1 .

Dual biotin/fluorescein conjugation. (A) Sequential dual labeling of thio-selenomab IgG1. First, the Sec residues (S396U) were reduced and conjugated with biotin-iodoacetamide. The biotinylated antibody was then reduced and partially oxidized prior to the conjugation with fluorescein-MSODA at the engineered Cys residues (A114C). (B) Western blot and in-gel fluorescence revealed the dual site-specific conjugation of the thio-selenomab (Cys/Sec). Only the antibodies with Sec residues were able to conjugate to biotin-iodoacetamide and only the antibodies with engineered Cys residues were able to conjugate with fluorescein-MSODA.