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. Author manuscript; available in PMC: 2018 Oct 3.
Published in final edited form as: Structure. 2017 Sep 14;25(10):1530–1539.e3. doi: 10.1016/j.str.2017.08.009

Figure 4. Binding of PPS-PHD to H3K4me3 is pH-dependent.

Figure 4

(a) Superimposed 1H,15N HSQC spectra of PPS-PHD, recorded while the H3K4me3 peptide was titrated in at pH 6.0. (b, f) Representative binding curves used to determine the Kd values by fluorescence at indicated pH. (c, g) Summary of binding affinities of WT and mutated PPS-PHD to H3K4me3 peptide as measured by tryptophan fluorescence. (d) A diagram showing the effect of protonation of H919. (e) Western blot analysis of pull-downs using GST-PPS-PHD and indicated biotinylated histone H3 peptides at pH 6.0. (h) A titration curve used to calculate the pKa value of H919.