The Binding Activity of G4S linker with Anti-G4S linker antibody. Activity: Measured by its binding ability in a functional ELISA. Immobilized Three recombinant proteins containing G4S linker at 2 μg/mL can bind Anti-G4S linker antibody. The EC<sub>50</sub> is 10.03 to 17.44 ng/mL, 22.60 to 28.76 ng/mL and 6.478 to 10.27 ng/mL.