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Characterizing the energetics and molecular dynamics of binding between proteins and bioactive compounds is strategic. Using surface plasmon resonance, we demonstrated that β-casein (β-cas) and quercetin (Qct) form supramolecular complexes driven by an increase in entropy (ΔH° = 25.86 and TΔS° =53.49 kJ∙mol -1 at 25 °C). It was possible to infer that the β-cas/Qct complex was formed via an activated complex synthesized by an entropic reduction (TΔS ‡ (a) = -15.31 kJ mol -1 and TΔS ‡ (d) = -68.80 kJ mol -1 at 25 °C) and an enthalpic increase (ΔH ‡ (a) = 30.87 and ΔH ‡ (d) =5.0 kJ∙mol -1 at 25 °C). Independent of the nature of the Hofmeister ions, the salts KCl or KSCN increased complex stability by decreasing both the kinetic and thermodynamic enthalpy values, through shielding of the electrostatic interactions at the electric double layer of the interacting molecules. An increase in temperature favored both the association of the free interacting molecules and the dissociation of the thermodynamically stable β-cas/Qct complexes. These results provide insights into the β-cas/Qct interaction process and contribute to the understanding of how Hofmeister ions can modulate intermolecular interactions between proteins and small molecules., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The objective of this study was to determine the thermodynamic parameters (Delta(tr)G, Delta(tr)H and Delta(tr)S) associated with lysozyme and conalbumin partitioning in aqueous two-phases systems (ATPS). Influence of salt type and polyethylene glycol (PEG) concentrations on the partition coefficient of lysozyme and conalbumin from egg white was studied. The evaluated ATPS were composed of PEG 1500 and inorganic salts (sodium citrate and sodium sulfate) at a temperature of 25 degrees C and pH 7.0, with PEG 1500 g mol(-1) concentrations of 14%, 16% and 18% (mass basis). Partitioning of lysozyme in PEG-citrate ATPS was enthalpically driven, however the PEG-sulfate ATPS was entropically driven. The tested systems can be employed for the separation of these two proteins in egg white, due to the fact that lysozyme migrates toward the polymeric phase and conalbumin to the saline phase in both ATPS. A high recovery of conalbumin in the saline phase of the PEG-sulfate ATPS was determined to be enthalpically driven.

To explore in vivo application of quantum dots (QDs), it is essential to understand the dynamics and energetics of interactions between QDs and proteins. Here, surface plasmon resonance (SPR) and molecular docking were employed to investigate the kinetics and thermodynamics of interactions between human serum albumin (HSA) and CdTe QDs (~3 nm) functionalized with mercaptopropionic acid (MPA) or thioglycolic acid (TGA). Kinetic analysis showed that HSA–QD interactions involved transition-complex formation. Despite the structural similarities between MPA and TGA, the [HSA−CdTe@TGA]‡ formation by association of free HSA and QDs demanded 70% more energy and higher entropic gain (E a − TGA ‡= 65.10 and T ∆ S a − TGA ‡= 28.62 kJ mol−1) than the formation of [HSA−CdTe@MPA]‡ (E a − MPA ‡ = 38.13 and T ∆ S a − MPA ‡ = 0.53kJ mol−1). While the [HSA−CdTe@MPA]° dissociation required higher energy and lower entropy loss (E d − MPA ‡ = 49.96 and T ∆ S d − MPA ‡ = − 32.18kJ mol−1) than the [HSA−CdTe@TGA]° dissociation (E d − TGA ‡= 30.78 and T ∆ S d − TGA ‡= − 51.12 kJ mol−1). The stability of [HSA−QDs]° was independent of the temperature and functionalizing group. However, the enthalpic and entropic components were highly affected by the substitution of MPA (ΔH ° = − 11.83 and TΔS ° = 32.72 kJ mol−1) with TGA (ΔH ° = 34.31 and TΔS ° = 79.73 kJ mol−1). Furthermore, molecular docking results indicated that the metal site on the QDs contributes to the stabilization of [HSA−QDs]°. Therefore, differences in QD functionalization and surface coverage densities can alter the HSA–QD interaction, thus their application. [Display omitted] • Human serum albumin (HSA) binds to CdTe quantum dots (QD) with high affinity. • [HSA − CdTe @ MPA]° stable complex formation was enthalpic and entropically favorable. • [HSA − CdTe @ TGA]° stable complex formation was entropically driven. • The QD surface coverage highly affects the thermodynamic and kinetic parameters. • The HSA-QD interaction mechanism is altered by the QD surface coverage density. [ABSTRACT FROM AUTHOR]

Bovine serum albumin (BSA)/curcumin binding and dye photodegradation stability were evaluated. BSA/curcumin complex showed 1:1 stoichiometry, but the thermodynamic binding parameters depended on the technique used and BSA conformation. The binding constant was of the order of 10 5 L·mol −1 by fluorescence and microcalorimetric, and 10 3 and 10 4 L·mol −1 by surface plasmon resonance (steady-state equilibrium and kinetic experiments, respectively). For native BSA/curcumin, fluorescence indicated an enthalpic and entropic driven process based on the standard enthalpy change (ΔH ○ F = −8.67 kJ·mol −1 ), while microcalorimetry showed an entropic driven binding process (ΔH ○ cal = 29.11 kJ·mol −1 ). For the unfolded BSA/curcumin complex, it was found thatp ΔH ○ F = −16.12 kJ·mol −1 and ΔH ○ cal = −42.63 kJ·mol −1 . BSA (mainly native) increased the curcumin photodegradation stability. This work proved the importance of using different techniques to characterize the protein-ligand binding. [ABSTRACT FROM AUTHOR]

In the third part of this series of studies, the adsorption of the basic textile dyes auramine-O (AO) and safranin-T (ST) on a carboxylated cellulose derivative (CTA) were evaluated in mono- and bi-component spiked aqueous solutions. Adsorption studies were developed as a function of solution pH, contact time, and initial dye concentration. Adsorption kinetic data were modeled by monocomponent kinetic models of pseudo-first- (PFO), pseudo-second-order (PSO), intraparticle diffusion, and Boyd, while the competitive kinetic model of Corsel was used to model bicomponent kinetic data. Monocomponent adsorption equilibrium data were modeled by the Langmuir, Sips, Fowler-Guggenhein, Hill de-Boer, and Konda models, while the IAST and RAST models were used to model bicomponent equilibrium data. Monocomponent maximum adsorption capacities for AO and ST at pH 4.5 were 2.841 and 3.691 mmol g −1 , and at pH 7.0 were 5.443 and 4.074 mmol g −1 , respectively. Bicomponent maximum adsorption capacities for AO and ST at pH 7.0 were 1.230 and 3.728 mmol g −1 . Adsorption enthalpy changes (Δ ads H ) were obtained using isothermal titration calorimetry. The values of Δ ads H ranged from −18.83 to −5.60 kJ mol −1 , suggesting that physisorption controlled the adsorption process. Desorption and re-adsorption of CTA was also evaluated. [ABSTRACT FROM AUTHOR]

To optimize the therapeutic applications of Congo red (CR), a potential inhibitor of protein aggregation, the kinetics and thermodynamics of the interactions between CR and a model protein need to be understood. We used surface plasmon resonance (SPR) and fluorescence techniques to determine the dynamics and thermodynamic parameters for the formation of complexes between CR and bovine serum albumin (BSA). CR interacts with BSA through a transition complex; the activation energy for association (E act(a) ) was determined to be 35.88 kJ mol −1 , while the activation enthalpy (ΔH ‡ ), entropy (ΔS ‡ ), and Gibbs free energy (ΔG ‡ ) are 33.41 kJ mol −1 , 0.18 J mol −1 K −1 , and 33.35 kJ mol −1 , respectively. When this intermediate transforms into the final CR-BSA complex, the entropy of the system increases and part of the absorbed energy is released; this process is associated with a reverse activation energy (E act(d) ) of 20.17 kJ mol −1 , and values of ΔH ‡ , ΔS ‡ , and ΔG ‡ of 17.69 kJ mol −1 , −162.86 J mol −1 K −1 , and 66.25 kJ mol −1 , respectively. A comparison of the SPR and fluorescence results suggests that there is more than one site where BSA interacts with CR. [ABSTRACT FROM AUTHOR]

Carbonaceous materials have been extensively studied as highly efficient adsorbents for the removal of dyes from wastewater. However, investigations of thermodynamic aspects of the interactions between these materials and dyes remain scarce. This paper describes the thermodynamics of the interactions between the Ponceau 4R (PR), Congo Red (CR), and Allura Red (AR) dyes and multi-walled carbon nanotubes (MWCNTs). The interactions between the dyes and activated carbon (AC) were also evaluated for comparison. The investigation used a combination of adsorption isotherms and isothermal titration nanocalorimetry (ITC) measurements, and a thermodynamic approach provided full characterization of the adsorption process. For both MWCNT and AC, the amount of adsorbed dye ( Γ D ) increased in the order Γ D (PR) < Γ D (AR) < Γ D (CR), and the adsorption capacity normalized by the adsorbent specific area was up to 5.6 times higher for MWCNT. The maximum amount adsorbed ( Γ D,max ) reached values of up to 2.00 μmol m −2 for CR adsorption on MWCNT. For both adsorbents, the process of dye adsorption was enthalpically driven and entropically unfavorable. All the thermodynamic parameters depended on the surface coverage and the structures of both dye and adsorbent. The adsorption enthalpy change (Δ ads H ) and entropy change (TΔ ads S ref ) values were higher than −137.0 kJ mol −1 and −114.2 kJ mol −1 , respectively. In addition to the structural differences between MWCNT and AC, the ITC data suggested that the adsorption sites are heterogeneous and that the dyes preferentially adsorb on the more hydrophilic sites on the adsorbent surfaces. [ABSTRACT FROM AUTHOR]

A new carboxylated cellulose derivative (CTA) was prepared from the esterification of cellulose with 1,2,4-Benzenetricarboxylic anhydride. CTA was characterized by percent weight gain ( pwg ), amount of carboxylic acid groups ( n COOH ), elemental analysis, FTIR, TGA, solid-state 13 C NMR, X-ray diffraction (DRX), specific surface area, pore size distribution, SEM and EDX. The best CTA synthesis condition yielded a pwg and n COOH of 94.5% and 6.81 mmol g −1 , respectively. CTA was used as an adsorbent material to remove Co 2+ , Cu 2+ and Ni 2+ from monocomponent spiked aqueous solution. Adsorption studies were developed as a function of the solution pH, contact time and initial adsorbate concentration. Langmuir model better fitted the experimental adsorption data and the maximum adsorption capacities estimated by this model were 0.749, 1.487 and 1.001 mmol g −1 for Co 2+ , Cu 2+ and Ni 2+ , respectively. The adsorption mechanism was investigated by using isothermal titration calorimetry. The values of Δ ads H ° were in the range from 5.36 to 8.09 kJ mol −1 , suggesting that the mechanism controlling the phenomenon is physisorption. Desorption and re-adsorption studies were also performed. Desorption and re-adsorption efficiencies were closer to 100%, allowing the recovery of both metal ions and CTA adsorbent. [ABSTRACT FROM AUTHOR]

Aqueous two-phase systems (ATPSs) are strategic liquid-liquid systems for extraction and purification of compounds. However, only a few studies have evaluated the thermodynamic parameters that allow comprehension of the partition process of different molecules. Here, we investigated the chymosin (Chy) partitioning behavior in macromolecule + salt + water ATPSs by obtaining the partition coefficient ( ), Gibbs free energy change of transfererence ( ), enthalpy change of transference ( ), and entropy change of transference ( ), at infinite dilution, and their dependence on the ATPS properties. Chy transfer from the bottom to the top phase of the ATPS was enthalpically driven, with -4.84 kJ mol-1 < < -170.34 kJ mol-1 and -11.69 J mol-1 K-1 < < -558.95 J mol-1 K-1 characterizing an enthalpy-entropy compensation process; -1.36 kJ mol-1 < < -3.77 kJ mol-1. became more negative as the tie-line length increased, showing that specific macromolecule-Chy interactions determine the enzyme concentration in the top phase. The nature of the cation/anion, hydrophobic/hydrophilic balance of the top phase, and macromolecule molar mass influence the intermolecular interaction between Chy and top phase components, changing the enzyme partition behavior. Negative parameters were attributed to the Chy transfer from a higher (bottom phase) to the lower (top phase) configurational entropy region. [ABSTRACT FROM AUTHOR]

Polydiacetylene (PDA) and triblock copolymer nanoblends were synthesized to detect micellar casein (MC), the main milk protein and an indicator of milk quality. UV–Vis spectrum showed that MC induced blue-to-red transition in nanoblends. When nanoblends and MC were separated by dialysis membrane colorimetric response (CR) was similar, whereas a remarkable CR reduction was noticed after addition of dialyzed-MC, suggesting that small molecules present in MC (salts) caused PDA color change. Interaction enthalpy variation between nanoblends and MC showed an abrupt increase that coincided with MC concentration when colorimetric transition occurred. Copolymer hydrophobic/hydrophilic balance and presence of other molecules in the system affected nanoblends CR. MC salts were found to interact with nanoblends leading to color changes. MC concentration, MC salt release, copolymer hydrophobic/hydrophilic balance, and presence of other molecules in the system affected responses of the sensors. These results contribute to future applications of PDA/copolymer nanosensors to dairy models. [ABSTRACT FROM AUTHOR]

[Display omitted] • Thermodynamically stable complexes are formed through activated complexes. • The water molecules of the desolvation layer influence the association. • The interaction causes a conformational change at the beta-lactoglobulin site. • At the low temperature (285.15 K) the hydrophobic interaction prevails. • At high temperatures (301.15 K), hydrophilic interactions are dominant. Despite some thermodynamics studies about β-lactoglobulin (βLG) and resveratrol (RES) interactions, there is a gap regarding kinetics data about βLG-RES complex formation. Here, we determined the kinetic and thermodynamic parameters of βLG-RES interactions by using surface plasmon resonance (SPR). The kinetic association parameters were dependent on the 3D water structure present on the solvation shell of both interacting molecules. At lower temperature (285.15 K), all activation energies were positive (E a c t a ‡ = 82.86 kJ.mol−1, T Δ S a ‡ = 32.26 kJ.mol−1, and Δ C p a ‡ = 4.15 kJ.mol−1K−1) due to the higher water structuration on the RES and βLG solvation shell. All these energetic barriers become mainly from the energetic cost for the desolvation process of RES and βLG. At higher temperature (301.15 K), the solvation water structure decreases and all the above activation energies become negative (E a c t a ‡ = - 121.58 kJ.mol−1, T Δ S a ‡ = - 173.59 kJ.mol−1, and Δ C p a ‡ = - 29.92 kJ.mol−1K−1) because the direct interaction between desolvated RES and βLG molecules released more energy than it is absorbed by desolvation process. However, kinetic dissociation parameters were not dependent on the hydrogen bond density of the water solvation shell as showed by the temperature independence of dissociation energetic parameters. This non-dependence of the dissociation process from the desolvation step probably is because the water molecules interacting with the βLG-RES complex is not concentrated around/inside the protein site of interaction. The association of free molecules was 1.5 times faster than the dissociation of the thermodynamically stable complex (Δ G (a) ‡ ≅ 48.15 kJ.mol−1, Δ G (d) ‡ ≅ 73.10 kJ.mol−1). The lower free energy barrier observed for the association came from an isokinetic process where entropic and enthalpic parameters compensated for each other. The ΔG° values indicate that the thermodynamically stable complex predominates over free molecules. At low temperature (285.15 K), the hydrophobic interaction (Δ H° = 73.06 kJ.mol−1; T Δ S° = 99.60 kJ.mol−1) drove the βLG-RES complex formation while at high temperature (301.15 K), hydrophilic interactions became dominant (Δ H° = −142.50 kJ.mol−1; T Δ S° = −118.18 kJ.mol−1). [ABSTRACT FROM AUTHOR]

• Peanut proteins (ARA or CON) interact with Congo red (CR) to form stable complexes. • CON has a higher binding affinity toward CR than does ARA. • Hydrophilic interactions were the main driving forces for [ A R A - C R ] 0 formation process. • The formation of [ C O N - C R ] 0 was enthalpically and entropically driven. • Transition complexes had a more structured conformation than their stable form. The thermodynamics and kinetics of arachin-Congo red (ARA - C R) and conarachin-Congo red (CON - C R) interactions were studied using surface plasmon resonance. KCl led to a reduction of up to 55% in the values of the associated kinetic constants, but it had less influence on the dissociation rates (less than 12%). The change in ionic strength had little effect on the thermodynamic stability of the complexes, but it did reduce their affinities (K b ( 25 ° C) [ A R A - C R ] 0 from 3.52 to 2.44 × 103 M−1 and K b (25 ° C) [ C O N - C R ] 0 from 15.1 to 12.5 × 103 M−1). The shielding of the electrical double layer favored ARA - C R hydrophilic interactions (Δ H [ A R A - C R ] 0 0 decreased from −30.60 to −42.98 kJ mol−1). On the other hand, hydrophobic interactions came to dominate during the formation of [ C O N - C R ] 0 (Δ H [ C O N - C R ] 0 0 increased from −11.21 to 28.34 kJ mol−1 and T Δ S 25 ° C [ C O N - C R ] 0 0 increased from 12.64 to 51.73 kJ.mol−1). The data presented here improve our understanding of plant-based protein nanocarriers of small bioactive molecules. [ABSTRACT FROM AUTHOR]

Abstract: In the present study, a thermodynamic analysis was performed using an isothermal titration microcalorimeter to measure changes in the enthalpy of mixing (ΔmixH) of water in microemulsion systems formed by soybean lecithin, isooctane and butanol. These energies were important to determine the driving forces associated with the formation of reverse micelles. It was observed that the titration curves of water in pure isooctane and in isooctane with soybean lecithin present values of ΔmixH equal to −9.46×10−3 kJ/mol and −5.68×10−3 kJ/mol, respectively. This shows that water does not form intermolecular interactions with these components. Exothermic behavior, with values of ΔmixH ranging from +2.17kJ/mol to −1.63×10−2 kJ/mol, was observed from the titration curve of water in systems formed by soybean lecithin, isooctane and butanol. These values were associated with the water dissolution process, where the formation of reverse micelles had been observed in the evaluated systems. Differences in behavior of ΔmixH for the water curves were observed in systems formed by butanol and soybean lecithin, only pure butanol and butanol with isooctane. The curve of the system containing soybean lecithin, butanol and isooctane clearly shows that the formation of aggregates occurred in this system (reverse micelles). Finally, it was also noted that soybean lecithin did not suffer any degradation process, since the energy involved in the process of water titration in the systems containing the same substance was considered low. Thus, soybean lecithin may be used without problems in this type of system. [Copyright &y& Elsevier]

Abstract: Partitioning of the natural dye norbixin has been studied in aqueous two-phase system (ATPS) that are formed by mixing aqueous solutions of a polymer (or copolymer) and an organic salt (sodium tartrate or succinate). In this work, the norbixin partition coefficient (K N) was optimized, taking into account the variables of polymer concentration, salt concentration and pH. It was found that K N is highly dependent on the electrolyte nature, system hydrophobicity and TLL values. Testing produced K N values between 8 and 130, indicating the great potential of ATPS as a method for norbixin pre-concentration/purification. Thermodynamic transfer parameters (Δtr G, Δtr H, Δtr S) indicate that the preferential concentration of norbixin in the top phase is favored by enthalpic and entropic contributions. [Copyright &y& Elsevier]

The present study includes measurements of the phase composition, density, and refractive index of aqueous two-phase systems of poly(ethylene oxide) 1500 (PEO1500) + sodium thiosulfate + H2O at (283.15, 298.15, and 313.15) K. With the experimental results obtained, phase diagrams were established, and the influence of temperature on the densities, binodal position, and refractive index values was analyzed and discussed. The experimental tie-lines were described using the Othmer–Tobias correlation. The experimental aqueous two-phase system data were correlated with the nonrandom two-liquid (NRTL) thermodynamic model for the activity coefficients; the results were considered excellent according to a global root-mean-square deviation of 0.97 %. [ABSTRACT FROM AUTHOR]

Abstract: The phase diagrams of PEO1500+sodium tartrate+water, PPO400+sodium tartrate+water, PEO1500+sodium succinate+water, PPO400+sodium succinate+water, PEO1500+sodium citrate+water, PPO400+sodium citrate+water and PPO400+sodium acetate+water aqueous two-phase systems were determined at (283.15, 298.15, and 313.15)K. Both equilibrium phases composition were analyzed by conductimetry and refractive index. In this paper, the influences of polymer hydrophobicity, salt nature and temperature on the phase diagram were analyzed. The phase separation processes was endothermic and the hydrophobic increase make easier the phase splitting, while the electrolyte capacity to induce phase separation follow the order: citrate>tartrate>succinate. The consistency of the tie-line data was ascertained by applying the Othmer–Tobias correlation. The experimental data were correlated with the NRTL model for the activity coefficient, with estimation of new interaction energy parameters. The results, analyzed in terms of root mean square deviations between experimental and calculated compositions, were considered satisfactory. [Copyright &y& Elsevier]

Abstract: Phase diagrams of two-phase systems (ATPS) composed by the triblock copolymer L64+organic salt (sodium tartrate, sodium succinate, sodium citrate, or ammonium citrate)+water, at different temperatures (278, 288, and 298K) are presented in this work. Contrary to behavior of ATPS formed by inorganic salts, the study of the temperature influence in the liquid–liquid equilibrium behavior of L64–organic salts ATPS showed an exothermic character for phase separation process. Microcalorimetric measurements showed that this phase separation energy is around −0.2kJmol−1 for all organic salts. The module of slope of tie line (STL) tends to increase with an increase in temperature. The cation nature effect showed that the salt Na3C6H5O7 was more effective in promoting phase separation than (NH4)3C6H5O7. The capacity of the different anions tested for inducing ATPS formation with L64 followed the order: C6H5O7 3− >C4H4O6 2− >C4H4O4 2−. Because the salt–L64 interaction energy to be very similar, the cation and anion effects on the phase separation could be attribute to a process driven by entropy. The interaction parameters of the NRTL and UNIFAC models were estimated through the experimental data of all ternary systems. The results of the NRTL (with 64 tie-lines) and UNIFAC (with 27 tie-lines) were considered excellent with global root mean square deviations, respectively, of the 1.04% and 0.87%. The consistencies of the all tie-line experimental compositions were improved by applying the Othmer–Tobias correlation. [Copyright &y& Elsevier]

Abstract: This study evaluates the influence of type of salt and temperature on the partition coefficient of caseinomacropetide (CMP) to determine the best conditions for the recovery of CMP in aqueous two-phase systems (ATPS) composed by poly(ethylene glycol) (PEG) 1500 and an inorganic salt (potassium phosphate, sodium citrate, lithium sulfate or sodium sulfate). In all systems, CMP presented affinity for the PEG-rich phase. The PEG1500+lithium sulfate showed the highest values of partitioning coefficient. In addition, thermodynamic parameters (ΔH°, ΔS°, ΔG°) as a function of temperature, were calculated for the system PEG1500-sodium citrate at different PEG concentrations and the results imply thermodynamic differences between partitioning of CMP in this system. [Copyright &y& Elsevier]

The incorporation of bioactive molecules is important to improve food functionality. Despite the low solubility of some bioactive molecules, e.g., flavonoids, their binding with proteins contribute to their incorporation. There are some studies regarding globular proteins as flavonoid nanocarriers, but binding between flavonoids and βCN monomers, which are flexible proteins, is less reported. Here, the thermodynamics and kinetics of naringin–β-casein (NR–βCN) binding were determined by fluorescence spectroscopy (FS) and surface plasmon resonance (SPR). FS indicated that NR binds with βCN close to Trp 143 with K b 24 ° C = 2.71 × 104 m −1 and a key role of desolvation. SPR revealed that NR also binds far from Trp 143 (K b 24 ° C = 7.01 × 103 m −1) with small enthalpic and entropic temperature dependencies. We also present the kinetic parameters related to an intermediate complex formation, which was formed with minimal conformation and desolvation changes. Our results demonstrate βCN monomers as potential nanocarriers for NR. [ABSTRACT FROM AUTHOR]

The thermodynamics of curcumin (CUR) binding with bovine lactoferrin (bLF) was investigated by employing fluorescence spectroscopy (FS) and surface plasmon resonance (SPR) and comparing the results. Moreover, the kinetics of bLF-CUR binding was studied using SPR. FS data showed that with an increase in temperature (from 293.15 to 306.15 K), more complexes were formed (K b ranged from 2.07 × 104 to 6.68 × 104 M−1) owing to an increase in the entropy (Δ H ° = 66.70 kJ mol−1; T Δ S ° ranged from 90.93 to 94.98 kJ mol−1), demonstrating the role of hydrophobic interactions. However, the bLF-CUR complex formation detected through the SPR technique was entropically and enthalpically driven below and above 293.75 K, respectively. SPR also demonstrated that an enthalpy increase is compensated by an entropy increase for both stable and activated complex formation, characterizing enthalpy-entropy compensation and iso-kinetic compensation, respectively. These results are helpful to better understand the dynamics of complex formation between proteins and small bioactive molecules. Image 1 • Curcumin (CUR) and bovine lactoferrin (bLF) formed a stable complex. • SPR showed that bLF has more sites for CUR binding than those close to tryptophan. • The stable bLF-CUR complex formation passes through an intermediate state. • The bLF-CUR interaction occurred with enthalpy-entropy compensation. • bLF-CUR binding is driven mainly by the conformational and desolvation processes. [ABSTRACT FROM AUTHOR]