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. 2018 Sep 17;221(18):jeb185470. doi: 10.1242/jeb.185470

Fig. 4.

Fig. 4.

O2 equilibrium curves and fitting of allosteric MWC parameters of bar-headed goose and greylag goose HbA and HbD. (A,B) O2 equilibrium curves of purified HbA (A) and HbD (B) from the bar-headed goose (BHG, closed symbols) and greylag goose (GLG, open symbols) covering a wide range of saturations (approaching 0% and 100%) to derive allosteric parameters describing Hb function according the MWC model. Measurements from five to nine separate experiments were carried out at a heme concentration of 0.3 mmol l−1 at 37°C, in 0.1 mol l−1 Hepes buffer, pH 7.4, in the absence (stripped) and presence of IHP (0.15 mmol l−1). The curves show fitting of all measured data under a given condition according to the saturation function (Eqn 1) describing the MWC model (parameters of this analysis are reported in Table S3). (C–H) Derived parameters (means±s.e.) logKT (C,D) and logKR (E,F), the O2 association equilibrium constants of the T and R states, respectively, and L (G,H), the allosteric equilibrium constant describing the [T]/[R] ratio in the absence of O2. Closed bars, bar-headed goose (BHG); open bars, greylag goose (GLG).