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Table 4 Binding affinity of IgG-Fc (upper rows) or IgG-Fab (lower rows) for PAB01 (WT) and PAB02 (D36H)

From: Engineered protein A ligands, derived from a histidine-scanning library, facilitate the affinity purification of IgG under mild acidic conditions

Protein pH = 7.4 pH = 5.0
KD(×10−9) (M−1) KDratio KD(×10−9) (M−1) KDratio
PAB01 (WT) 12.8 - 1080 -
PAB02 (D36H) 15.5 1.2 1350 1.3
  pH = 7.4 pH = 5.0
Protein K D (×10 −5 ) (M −1 ) K D ratio K D (×10 −5 ) (M −1 ) K D ratio
PAB01 (WT) 2.9 - ND -
PAB02 (D36H) 6.7 2.3 ND -
  1. The binding assay was performed under neutral (pH = 7.4) and acidic (pH = 5.0) conditions using SPR. IgG-Fc or IgG-Fab was immobilized on the surface of a CM5 sensor chip (GE Healthcare).
  2. KD, equilibrium dissociation constant: KD ratio, (KD of histidine-substituted PAB variant)/(KD of Wild-type PAB or PAZ): ND, not determined.