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Table 2 The pH values of the IgG elution peaks and the thermal stability of PAB variants

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

Protein Elution Peak ∆pH Stability ∆T m
pH Tm(K)
PAB01 (Wild Type) 3.5 - 346.4 -
PAB02 (D36H) 4.6 1.1 345.8 −0.6
PAB03 (Q09H, D36H) 5.5 2.0 343.7 −2.7
PAB04 (Q10H, D36H) 6.8 3.3 343.1 −3.3
PAB05 (R27H, D36H) 4.7 1.2 316.2 −30.2
PAB06 (K35H, D36H) 4.4 0.9 342.5 −3.9
PAB07 (Q09H) 3.9 0.4 344.9 −1.5
PAB08 (Q10H) 3.7 0.2 343.6 −2.8
PAB10 (Q32H) 4.2 0.7 341.4 −5.0
  1. Affinity columns were prepared using the PAB variants. The captured IgG on each column was eluted with a decreasing pH gradient. The pH value in the table indicates the peak position of the eluted IgG on the affinity chromatography. The midpoint of the transition during thermal denaturation (Tm) was determined from circular dichroism melting measurements.
  2. ∆pH = (the pH value at which IgG eluted from mutant column) - (the pH value at which IgG eluted from wild-type column).
  3. ∆Tm = (the thermal stability of PAB mutant expressed as Tm) - (that of the thermal stability of PAB wild-type, PAB01).