Fig. 2. The two binding sites of CaDoc0917 have different affinity changes as a response to pH change.

(A) Proposed dynamic model of the pH-dependent features of the CaDoc0917-CaCohA2 interaction. An arbitrary sigmoid curve was used for the pH-dependent affinity change for each orientation. (B and C) NMR titrations of CaDoc0917 (left panels), CaDoc0917(R16D) (middle panels), and CaDoc0917(R49D) (right panels) with CaCohA2 at pH 4.8 (B) and pH 7.5 (C). The spectra of CaDoc0917:CaCohA2 at molar ratios of 1:0, 1:0.2, 1:0.4, 1:0.6, 1:0.8, and 1:1.0 are shown in black, blue, green, cyan, pink, and red, respectively. (D) Results of ITC experiments of CaDoc0917(R16D) and CaDoc0917(R49D) binding with CaCohA2 under different pH conditions.