PMC

(a) The SVD-resolved two species-associated spectra centered at 1623 cm⁻¹ and 1629 cm⁻¹. (b) The population thermal titration curves of the structure components (1623 cm⁻¹, 1629 cm⁻¹) retrieved by SVD analysis. (c) The absorbance thermal titration curve at 1651 cm⁻¹ and the population thermal titration curve of the structure component at 1629 cm⁻¹.

Thermodynamical properties of AgNPs and ICR-191 interactions. (a) Thermal effects of titrations of naked AgNPs with ICR-191 (squares), buffer with ICR-191 (circles), and naked AgNPs with buffer (triangles). Black diamonds represent difference between the heat of naked AgNPs titration with ICR-191 and sum of heats obtained for control titrations (buffer-ICR-191, naked AgNPs-buffer); (b) heat of ICR-191-naked AgNPs interactions (corrected for background thermal effects as described above), calculated as kcal mol⁻¹ of injected ICR-191. The enthalpy change (ΔH) of ICR-191-naked AgNPs interactions, calculated by the linear regression (R² = 0.952) of experimental points to [ICR-191] tending to zero, is equal to −2.775 ± 0.123 (±SE) kcal mol⁻¹; (c) thermal effects of titrations of AgNP-TBA with ICR-191 (squares), buffer with ICR-191 (circles), and AgNP-TBA with buffer (triangles). Black diamonds represent difference between the heat of AgNP-TBA titration with ICR-191 and sum of heats obtained for control titrations (buffer-ICR-191, AgNP-TBA-buffer); (d) heat of ICR-191-AgNP-TBA interactions (corrected for background thermal effects as described above), calculated as kcal mol⁻¹ of injected ICR-191. The enthalpy change (ΔH) of ICR-191-AgNP-TBA interactions, calculated by the linear regression (R² = 0.918) of experimental points to [ICR-191] tending to zero, is equal to 4.547 ± 0.059 (±SE) kcal mol⁻¹; (e) thermal effects of titrations of AgNP-MUA with ICR-191 (squares), buffer with ICR-191 (circles), and AgNP-MUA with buffer (triangles). Black diamonds represent difference between the heat of AgNP-MUA titration with ICR-191 and sum of heats obtained for control titrations (buffer-ICR-191, AgNP-MUA-buffer); (f) heat of ICR-191-AgNP-MUA interactions (corrected for background thermal effects as described above), calculated as kcal mol⁻¹ of injected ICR-191. The enthalpy change (ΔH) of ICR-191-AgNP-MUA interactions, calculated by the linear regression (R² = 0.839) of experimental points to [ICR-191] tending to zero, is equal to 6.147 ± 0.049 (±SE) kcal mol⁻¹.

Representative ITC assays are shown. The upper part of each panel shows the thermogram (thermal power vs. time) after baseline correction and the bottom part of each panel shows the binding isotherm (normalized heat vs. molar ratio of reactants). (A) Calorimetric titration for VBP. (B) Calorimetric titration for VBP N186D. (C) Calorimetric titration for HEPN.

PfSpdS in the reaction cell was titrated with each indicated ligand in the syringe. Each upper panel shows the raw thermal data, and each lower panel shows the integrated binding heats (black squares) and the best nonlinear regression fit using a single-site binding model (solid line). The solid line in each lower panel is described by the thermodynamic parameters given in . Representative results are shown for selected ligands: (A) Titration of dcAdoMet into ligand-free PfSpdS. (B) Titration of MTA into ligand-free PfSpdS. (C) Titration of AdoDATO into ligand-free PfSpdS. (D) Titration of putrescine into PfSpdS saturated with MTA. (E) Titration of 4AMA into PfSpdS saturated with MTA. (F) Titration of 4MAN into PfSpdS saturated with dcAdoMet.