Biacore kinetic and affinity determinations on purified, recombinant antigens.

aThe “% activity” was determined via titration-based assays on the Octet and used to correct all ka values.bNot determined.cActivity determined by CFCA.dThe apparent ka values determined via KinExA were 1.05×107 M−1s−1 and 1.07×107 M−1s−1 for human DKK1 and 1.4×107 M−1s−1 and 0.80×107 M−1s−1 for human DKK4 in two independent experiments each.eThe resolution limit of the assay, according to the “5% rule”.fMeasured in a kosmotropic buffer containing 150 mM (NH4)2SO4 instead of 150 mM NaCl.