ß-lactoglobulin and resveratrol nanocomplex formation is driven by solvation water release.

Despite some thermodynamics studies about ß-lactoglobulin (ßLG) and resveratrol (RES) interactions, there is a gap regarding kinetics data about ßLG-RES complex formation. Here, we determined the kinetic and thermodynamic parameters of ßLG-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 (Eacta‡= 82.86 kJ.mol-1,TΔSa‡= 32.26 kJ.mol-1, and ΔCpa‡= 4.15 kJ.mol-1K-1) due to the higher water structuration on the RES and ßLG solvation shell. All these energetic barriers become mainly from the energetic cost for the desolvation process of RES and ßLG. At higher temperature (301.15 K), the solvation water structure decreases and all the above activation energies become negative (Eacta‡=-121.58 kJ.mol-1,TΔSa‡=-173.59 kJ.mol-1, and ΔCpa‡=-29.92 kJ.mol-1K-1) because the direct interaction between desolvated RES and ßLG 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 ßLG-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 (ΔG(a)‡â€¯â‰… 48.15 kJ.mol-1, ΔG(d)‡â€¯â‰… 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 (ΔH° = 73.06 kJ.mol-1; TΔS° = 99.60 kJ.mol-1) drove the ßLG-RES complex formation while at high temperature (301.15 K), hydrophilic interactions became dominant (ΔH° = -142.50 kJ.mol-1; TΔS° = -118.18 kJ.mol-1).

Application of Congo red dye as a molecular probe to investigate the kinetics and thermodynamics of the formation processes of arachin and conarachin nanocomplexes.

The thermodynamics and kinetics of arachin-Congo red (ARA-CR) and conarachin-Congo red (CON-CR) 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 ( [Formula: see text] from 3.52 to 2.44 × 103 M-1 and [Formula: see text] from 15.1 to 12.5 × 103 M-1). The shielding of the electrical double layer favored ARA-CR hydrophilic interactions ( [Formula: see text] decreased from -30.60 to -42.98 kJ mol-1). On the other hand, hydrophobic interactions came to dominate during the formation of [CON-CR]0 ( [Formula: see text] increased from -11.21 to 28.34 kJ mol-1 and [Formula: see text] 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.

Kinetic and thermodynamic of lactoferrin - Ethoxylated-nonionic surfactants supramolecular complex formation.

Understanding nonionic surfactant-protein interactions is fundamental from both technological and scientific points of view. However, there is a complete absence of kinetic data for such interactions. We employed surface plasmon resonance (SPR) to determine the kinetic and thermodynamic parameters of bovine lactoferrin-Brij58 interactions at various temperatures under physiological conditions (pH 7.4). The adsorption process was accelerated with increasing temperature, while the desorption rate decreased, resulting in a more thermodynamically stable complex. The kinetic energetic parameters obtained for the formation of the activated complex, [bLF-Brij58]‡, indicated that the potential energy barrier for [bLF-Brij58]‡ formation arises primarily from the reduction in system entropy. [bLF-Brij58]○ formation was entropically driven, indicating that hydrophobic interactions play a fundamental role in bLF interactions with Brij58.

Thermodynamic and kinetic insights into the interactions between functionalized CdTe quantum dots and human serum albumin: A surface plasmon resonance approach.

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 (Ea-TGA‡= 65.10 and T∆Sa-TGA‡= 28.62 kJ mol-1) than the formation of [HSA-CdTe@MPA]‡ (Ea-MPA‡ = 38.13 and T∆Sa-MPA‡ = 0.53kJ mol-1). While the [HSA-CdTe@MPA]° dissociation required higher energy and lower entropy loss (Ed-MPA‡ = 49.96 and T∆Sd-MPA‡ = - 32.18kJ mol-1) than the [HSA-CdTe@TGA]° dissociation (Ed-TGA‡= 30.78 and T∆Sd-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.

Human serum albumin-resveratrol complex formation: Effect of the phenolic chemical structure on the kinetic and thermodynamic parameters of the interactions.

The thermodynamics and kinetics of binding between human serum albumin (HSA) and resveratrol (RES) or its analog (RESAn1) were investigated by surface plasmon resonance (SPR). The binding constant and the kinetic constants of association and dissociation indicated that RESAn1 has higher affinity toward HSA than does RES. The formation of these complexes was entropically driven ( [Formula: see text] , [Formula: see text]  KJ mol-1). However, for both polyphenols, the activation energy (Eact) of association (a) of free molecules was higher than that for dissociation (d) of the stable complex ( [Formula: see text]  KJ mol-1), and the rate of association was faster than that of dissociation since the activation Gibbs free energy (ΔG‡) was lower for the former (ΔGaHSA-RES‡â‰…54.73,ΔGdHSA-RES‡â‰…73.83,ΔGaHSA-RESAn1‡â‰…54.14,ΔGdHSA-RESAn1‡â‰…73.97 KJ mol-1). This study showed that small differences in the structure of polyphenols such as RES and RESAn1 influenced the thermodynamics and kinetics of the complex formation with HSA.

Energetic parameters of ß-casein/quercetin activated and thermodynamically stable complex formation accessed by Surface Plasmon Resonance.

Characterizing the energetics and molecular dynamics of binding between proteins and bioactive compounds is strategic. Using surface plasmon resonance, we demonstrated that ß-casein (ß-cas) and quercetin (Qct) form supramolecular complexes driven by an increase in entropy (ΔH°â€¯= 25.86 and TΔS° =53.49 kJ∙mol-1 at 25 °C). It was possible to infer that the ß-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 ß-cas/Qct complexes. These results provide insights into the ß-cas/Qct interaction process and contribute to the understanding of how Hofmeister ions can modulate intermolecular interactions between proteins and small molecules.

Curcumin-micellar casein multisite interactions elucidated by surface plasmon resonance.

Determine the thermodynamic and kinetic parameters of interaction between micellar casein (MC) and curcumin (CUR) is useful for the application of MC-CUR systems in food products. We used surface plasmon resonance (SPR) and ultraviolet-visible spectrophotometry (UV-vis) to study the complex formation between MC obtained from skimmed milk and CUR, MC carrying capacity, and thermal protection for CUR at a pH of 6.6. An MC could carry about 18,000 molecules of CUR. SPR suggested an enthalpy-driven process (∆H°â€¯= -64.63 kJ∙mol-1 and T∆S° ranging from -42.45 to -44.46 kJ∙mol-1). Temperature increased reduced the rate of MC-CUR complex formation and increased its dissociation rate. The activation energy for the formation of MC-CUR activated complexes was negative for association of free MC and CUR molecules (-62.8 kJ mol-1) and positive for dissociation of the thermodynamically stable complexes (1.80 kJ mol-1). MC protected the CUR against its thermal degradation when it was subjected to different temperatures (30, 40, 50, and 60 °C for 5.5 h). This study shows the importance of characterizing MC-small molecules interactions for better application of MC as a nanocarrier.

Thermodynamic and kinetic analyses of curcumin and bovine serum albumin binding.

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 105L·mol-1 by fluorescence and microcalorimetric, and 103 and 104L·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=-8.67kJ·mol-1), while microcalorimetry showed an entropic driven binding process (ΔH○cal=29.11kJ·mol-1). For the unfolded BSA/curcumin complex, it was found thatp ΔH○F=-16.12kJ·mol-1 and ΔH○cal=-42.63kJ·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.

Kinetics and thermodynamics of bovine serum albumin interactions with Congo red dye.

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 (Eact(a)) was determined to be 35.88kJmol-1, while the activation enthalpy (ΔH‡), entropy (ΔS‡), and Gibbs free energy (ΔG‡) are 33.41kJmol-1, 0.18Jmol-1K-1, and 33.35kJmol-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 (Eact(d)) of 20.17kJmol-1, and values of ΔH‡, ΔS‡, and ΔG‡ of 17.69kJmol-1, -162.86Jmol-1K-1, and 66.25kJmol-1, respectively. A comparison of the SPR and fluorescence results suggests that there is more than one site where BSA interacts with CR.