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. 2020 Nov 6;21(21):8331. doi: 10.3390/ijms21218331

Figure 3.

Figure 3

Fluorescence competitive ligand-binding assays of SaveOBP9. (A) The binding curves for 1-NPN SaveOBP9 at two different pH, i.e., pH 5.0 and 7.4. A 2 μM solution of SaveOBP9 in 30 mM Tris-HCL buffer (for pH 5.0 and 7.4, used separately) was titrated through a 1 mM 1-NPN solution in spectrophotometric-grade methanol to an ultimate concentration of 0–20 μM, and the emission spectrum was recorded between 350 and 600 nm. (B) Comparison of ligand binding affinity (indicated by 1/Ki × 1000) of SaveOBP9 with 30 compounds at pH 5.0 and 7.4. (C,G) Competitive binding curves of compounds identified in GC-MS, (D,H) general odorants and phenylpropanoids, (E,I) terpenoids, (F,J) green leaf volatiles and alcohols to SaveOBP9 at pH 5.0 and 7.4, respectively. A mixture of the recombinant SaveOBP9 and 1-NPN in 30 mM Tris-HCL (pH 5.0 and pH 7.4) was titrated with 1 mM solution of each competing ligand to an ultimate concentration of 0–20 μM.