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Table 3 Binding affinity of IgG for PAB variants

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

  pH = 7.4 pH = 5.0
Protein KD(×10−9) (M−1) KDratio KD(×10−9) (M−1) KDratio
PAB01 (WT) 5.1 ± 3.2 - 7.6 ± 4.3 -
PAB02 (D36H) 33.6 ± 19.2 6.6 832 ± 443 110
PAB03 (Q9H, D36H) 288 ± 146 56 ND -
PAB04 (Q10H, D36H) 6830 ± 3600 1300 ND -
PAB05 (R27H, D36H) 80.7 16 2090 270
PAB06 (K35H, D36H) 550 ± 143 110 3860 510
PAB07 (Q9H) 13.9 ± 6.3 2.7 30.6 4
PAB08 (Q10H) 50.8 ± 20.5 10 951 120
PAB09 (R27H) 5.6 ± 1.3 1.1 7.0 0.92
PAB10 (Q32H) 2.8 ± 1.3 0.55 96.8 13
  1. The binding assay was performed under neutral (pH = 7.4) and acidic (pH = 5.0) conditions using SPR. The IgG 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): ND, not determined.