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Fahy KM, Sha F, Reischauer S, Lee S, Tai TY, Farha OK. Role of Metal-Organic Framework Topology on Thermodynamics of Polyoxometalate Encapsulation. ACS APPLIED MATERIALS & INTERFACES 2024; 16:30296-30305. [PMID: 38825765 DOI: 10.1021/acsami.4c05016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
Polyoxometalates (POMs) are discrete anionic clusters whose rich redox properties, strong Bro̷nsted acidity, and high availability of active sites make them potent catalysts for oxidation reactions. Metal-organic frameworks (MOFs) have emerged as tunable, porous platforms to immobilize POMs, thus increasing their solution stability and catalytic activity. While POM@MOF composite materials have been widely used for a variety of applications, little is known about the thermodynamics of the encapsulation process. Here, we utilize an up-and-coming technique in the field of heterogeneous materials, isothermal titration calorimetry (ITC), to obtain full thermodynamic profiles (ΔH, ΔS, ΔG, and Ka) of POM binding. Six different 8-connected hexanuclear Zr-MOFs were investigated to determine the impact of MOF topology (csq, scu, and the) on POM encapsulation thermodynamics.
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Affiliation(s)
- Kira M Fahy
- Department of Chemistry and International Institute for Nanotechnology (IIN), Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Fanrui Sha
- Department of Chemistry and International Institute for Nanotechnology (IIN), Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Susanne Reischauer
- Department of Chemistry and International Institute for Nanotechnology (IIN), Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Seryeong Lee
- Department of Chemistry and International Institute for Nanotechnology (IIN), Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Tzu-Yi Tai
- Department of Chemistry and International Institute for Nanotechnology (IIN), Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Omar K Farha
- Department of Chemistry and International Institute for Nanotechnology (IIN), Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Department of Chemical & Biological Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
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Assaf Z, Wurster DE. Molecular Dynamics of Hydration Shells of Adsorbates in Entropy-Driven Adsorption (Hydrophobic Bonding) to Activated Carbon Surfaces. J Pharm Sci 2024; 113:982-989. [PMID: 37967652 DOI: 10.1016/j.xphs.2023.10.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 10/02/2023] [Accepted: 10/02/2023] [Indexed: 11/17/2023]
Abstract
Hydrophobic bonding is a phenomenon wherein the adsorption of solutes from aqueous solutions is driven largely by the desire of solvent molecules to interact with each other, thus squeezing out solute molecules onto the adsorbent surface. A novel computational analysis of hydration shell water dynamics was used to study the driving force for the hydrophobic bonding of five small drug molecules to activated carbon. It was demonstrated that the solvation of these drug molecules produced hydration shells of lower density and molecular mobility than bulk water, up to 10.5-14 Å distance. Excellent correlations were found between the simulated water-water hydrogen bonding lifetimes in the hydration shell and the experimental capacity constants of hydrophobic bonding (KHB) obtained from the Two-Mechanism Langmuir-Like Equation. KHB also correlated well with the solute-solvent vdW interaction energies in a manner that could allow future predictions of KHB values from simple simulations. Such correlations were not found with the capacity constant of the well-known enthalpy-driven adsorption. The driving force for hydrophobic bonding has entropic origins due to the elimination of water structuring in the hydration shells. However, unlike a typical entropy-driven process, hydrophobic bonding to activated carbon was also associated with a large exothermic enthalpy change when studied with isoperibol calorimetry.
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Affiliation(s)
- Zaid Assaf
- AbbVie, 1 N. Waukegan Road North Chicago, IL 60064, USA.
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Kerep R, Šeba T, Borko V, Weitner T, Keser T, Lauc G, Gabričević M. Potential Clinically Relevant Effects of Sialylation on Human Serum AAG-Drug Interactions Assessed by Isothermal Titration Calorimetry: Insight into Pharmacoglycomics? Int J Mol Sci 2023; 24:8472. [PMID: 37239819 PMCID: PMC10218007 DOI: 10.3390/ijms24108472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 04/18/2023] [Accepted: 04/25/2023] [Indexed: 05/28/2023] Open
Abstract
Human serum alpha-1 acid glycoprotein is an acute-phase plasma protein involved in the binding and transport of many drugs, especially basic and lipophilic substances. It has been reported that the sialic acid groups that terminate the N-glycan chains of alpha-1 acid glycoprotein change in response to certain health conditions and may have a major impact on drug binding to alpha-1 acid glycoprotein. The interaction between native or desialylated alpha-1 acid glycoprotein and four representative drugs-clindamycin, diltiazem, lidocaine, and warfarin-was quantitatively evaluated using isothermal titration calorimetry. The calorimetry assay used here is a convenient and widely used approach to directly measure the amount of heat released or absorbed during the association processes of biomolecules in solution and to quantitatively estimate the thermodynamics of the interaction. The results showed that the binding of drugs with alpha-1 acid glycoprotein were enthalpy-driven exothermic interactions, and the binding affinity was in the range of 10-5-10-6 M. Desialylated alpha-1 acid glycoprotein showed significantly different binding with diltiazem, lidocaine, and warfarin compared with native alpha-1 acid glycoprotein, whereas clindamycin showed no significant difference. Therefore, a different degree of sialylation may result in different binding affinities, and the clinical significance of changes in sialylation or glycosylation of alpha-1 acid glycoprotein in general should not be neglected.
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Affiliation(s)
- Robert Kerep
- Department of General and Inorganic Chemistry, Faculty of Pharmacy and Biochemistry, University of Zagreb, 10000 Zagreb, Croatia
| | - Tino Šeba
- Department of General and Inorganic Chemistry, Faculty of Pharmacy and Biochemistry, University of Zagreb, 10000 Zagreb, Croatia
| | - Valentina Borko
- Department of General and Inorganic Chemistry, Faculty of Pharmacy and Biochemistry, University of Zagreb, 10000 Zagreb, Croatia
| | - Tin Weitner
- Department of General and Inorganic Chemistry, Faculty of Pharmacy and Biochemistry, University of Zagreb, 10000 Zagreb, Croatia
| | - Toma Keser
- Department of Biochemistry and Molecular Biology, Faculty of Pharmacy and Biochemistry, University of Zagreb, 10000 Zagreb, Croatia
| | - Gordan Lauc
- Department of Biochemistry and Molecular Biology, Faculty of Pharmacy and Biochemistry, University of Zagreb, 10000 Zagreb, Croatia
| | - Mario Gabričević
- Department of General and Inorganic Chemistry, Faculty of Pharmacy and Biochemistry, University of Zagreb, 10000 Zagreb, Croatia
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Assaf Z, Wurster DE. Disagreements Between Calorimetric and Van't Hoff Enthalpies of Adsorption II: Effect of pH and pH Buffers on Phenobarbital Adsorption to Activated Carbon. J Pharm Sci 2023; 112:100-107. [PMID: 36372228 DOI: 10.1016/j.xphs.2022.11.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2022] [Revised: 11/05/2022] [Accepted: 11/05/2022] [Indexed: 11/13/2022]
Abstract
The reported inconsistencies between the van't Hoff equation and calorimetry hinder the utility of thermodynamics in biochemical and pharmaceutical research. A novel thermodynamic approach is developed herein for ligand adsorption with a focus on the interpretation of calorimetric data in the presence of concurrent proton exchange reactions. Such exchange reactions typically result in a pH-dependence of calorimetric measurements that obscures intrinsic binding enthalpies. It is shown that for the adsorption of phenobarbital to activated carbon, the measured calorimetric enthalpy is a result of three linked acid/base equilibria. A model was established to predict the intrinsic binding enthalpy using 1) the adsorbate's pKa and 2) the adsorbate's enthalpy of protonation. The observed calorimetric enthalpy of binding exhibited both pH and buffer-dependence and was between -5 and -42 kJ/mol. Meanwhile, the predicted intrinsic enthalpy (-25.1 kJ/mol) of binding was in excellent agreement with the measured intrinsic enthalpy (-25.6 kJ/mol). Corrections to the observed calorimetric enthalpies allowed comparisons with enthalpies obtained from the van't Hoff method. It is shown that the predicted intrinsic calorimetric enthalpy agrees well with the van't Hoff enthalpies in instances where observed enthalpies significantly deviated. This treatment is general and is not specific to phenobarbital or activated carbon.
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Affiliation(s)
- Zaid Assaf
- AbbVie, North Chicago, IL, 60064, United States
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Assaf Z, Wurster DE. Disagreements Between Calorimetric and Van't Hoff Enthalpies of Adsorption: A New Langmuir-like Model to Account for the Effect of Solvent Displacement Stoichiometry. J Pharm Sci 2023; 112:91-99. [PMID: 35605689 DOI: 10.1016/j.xphs.2022.05.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 05/05/2022] [Accepted: 05/05/2022] [Indexed: 12/01/2022]
Abstract
The reported inconsistencies between calorimetry and the van't Hoff equation hinder the utility of thermodynamics in pharmaceutical research. In ligand binding or adsorption assays, it is believed that the van't Hoff equation falls short because of the lack of stoichiometric treatment in the equilibrium constant. A new modified Langmuir-Like equation that accounts for the stoichiometry of solute adsorption and solvent displacement is proposed in this work. The performance of the model was evaluated by studying the adsorption of phenobarbital from aqueous solutions by commercial activated carbon. The amount of water occupying the adsorption sites was estimated by graphical analysis of the 'knee point' of water-vapor adsorption isotherms and was found to correlate well with the relative percentage of hydroxyl and carbonyl surface groups. It was found that one phenobarbital molecule displaces 2-6 water molecules from the adsorption site. It is shown that adsorption enthalpy was not affected by the adjustment for stoichiometry, supporting the notion that the van't Hoff enthalpy is intrinsic and is independent of the stoichiometry of solvent displacement in Langmuir-based binding. The widely reported disparities between the van't Hoff and calorimetric enthalpies are unlikely to be from a stoichiometric origin.
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Affiliation(s)
- Zaid Assaf
- College of Pharmacy University of Iowa, Iowa City, IA, 52242
| | - Dale Eric Wurster
- Professor Emeritus, College of Pharmacy University of Iowa, Iowa City, IA 52242.
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Bor G, Bulut U, Man E, Balaban Hanoglu S, Evran S, Timur S. Synthetic antibodies for methamphetamine analysis: Design of high affinity aptamers and their use in electrochemical biosensors. J Electroanal Chem (Lausanne) 2022. [DOI: 10.1016/j.jelechem.2022.116686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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Zakharov SD, Savikhin S, Misumi Y, Kurisu G, Cramer WA. Isothermal titration calorimetry of membrane protein interactions: FNR and the cytochrome b 6f complex. Biophys J 2022; 121:300-308. [PMID: 34902329 PMCID: PMC8790201 DOI: 10.1016/j.bpj.2021.12.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 06/03/2021] [Accepted: 12/09/2021] [Indexed: 01/21/2023] Open
Abstract
Ferredoxin-NADP+ reductase (FNR) was previously inferred to bind to the cytochrome b6f complex in the electron transport chain of oxygenic photosynthesis. In the present study, this inference has been examined through analysis of the thermodynamics of the interaction between FNR and the b6f complex. Isothermal titration calorimetry (ITC) was used to characterize the physical interaction of FNR with b6f complex derived from two plant sources (Spinacia oleracea and Zea maize). ITC did not detect a significant interaction of FNR with the b6f complex in detergent solution nor with the complex reconstituted in liposomes. A previous inference of a small amplitude but defined FNR-b6f interaction is explained by FNR interaction with micelles of the undecyl β-D maltoside (UDM) detergent micelles used to purify b6f. Circular dichroism, employed to analyze the effect of detergent on the FNR structure, did not reveal significant changes in secondary or tertiary structures of FNR domains in the presence of UDM detergent. However, thermodynamic analysis implied a significant decrease in an interaction between the N-terminal FAD-binding and C-terminal NADP+-binding domains of FNR caused by detergent. The enthalpy, ΔHo, and the entropy, ΔSo, associated with FNR unfolding decreased four-fold in the presence of 1 mM UDM at pH 6.5. In addition to the conclusion regarding the absence of a binding interaction of significant amplitude between FNR and the b6f complex, these studies provide a precedent for consideration of significant background protein-detergent interactions in ITC analyses involving integral membrane proteins.
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Affiliation(s)
| | - Sergei Savikhin
- Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana
| | - Yuko Misumi
- Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana
| | - Genji Kurisu
- Institute for Protein Research, Osaka University, Suita, Osaka
| | - William A Cramer
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana.
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Witkowska D, Szebesczyk A, Wątły J, Braczkowski M, Rowińska-Żyrek M. A Comparative Study on Nickel Binding to Hpn-like Polypeptides from Two Helicobacter pylori Strains. Int J Mol Sci 2021; 22:ijms222413210. [PMID: 34948007 PMCID: PMC8704837 DOI: 10.3390/ijms222413210] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 11/19/2021] [Accepted: 12/02/2021] [Indexed: 01/15/2023] Open
Abstract
Combined potentiometric titration and isothermal titration calorimetry (ITC) methods were used to study the interactions of nickel(II) ions with the N-terminal fragments and histidine-rich fragments of Hpn-like protein from two Helicobacter pylori strains (11637 and 26695). The ITC measurements were performed at various temperatures and buffers in order to extract proton-independent reaction enthalpies of nickel binding to each of the studied protein fragments. We bring up the problem of ITC results of nickel binding to the Hpn-like protein being not always compatible with those from potentiometry and MS regarding the stoichiometry and affinity. The roles of the ATCUN motif and multiple His and Gln residues in Ni(II) binding are discussed. The results provided the possibility to compare the Ni(II) binding properties between N-terminal and histidine-rich part of Hpn-like protein and between N-terminal parts of two Hpn-like strains, which differ mainly in the number of glutamine residues.
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Affiliation(s)
- Danuta Witkowska
- Institute of Health Sciences, University of Opole, Katowicka 68, 45-060 Opole, Poland;
- Correspondence:
| | - Agnieszka Szebesczyk
- Institute of Health Sciences, University of Opole, Katowicka 68, 45-060 Opole, Poland;
| | - Joanna Wątły
- Faculty of Chemistry, University of Wroclaw, F. Joliot-Curie 14, 50-383 Wroclaw, Poland; (J.W.); (M.R.-Ż.)
| | - Michał Braczkowski
- Institute of Medical Sciences, University of Opole, Oleska 48, 45-052 Opole, Poland;
| | - Magdalena Rowińska-Żyrek
- Faculty of Chemistry, University of Wroclaw, F. Joliot-Curie 14, 50-383 Wroclaw, Poland; (J.W.); (M.R.-Ż.)
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ITC for Characterization of Self-Assembly Process of Cationic Dendrons for siRNA Delivery. Methods Mol Biol 2021; 2282:245-266. [PMID: 33928580 DOI: 10.1007/978-1-0716-1298-9_15] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
siRNAs are emerging as promising therapeutic agents due to their ability to inhibit specific genes in many diseases. However, these tools require specific vehicles in order to be safely delivered to the targeted site. Among different siRNA delivery systems, self-assembled nanomicelles based on amphiphilic cationic dendrons (ACDs) have recently outperformed nanovectors based on covalent carriers. This chapter describes how isothermal titration calorimetry (ITC) can be exploited as one of the best techniques to investigate the self-assembly process of ACDs. Specifically, ITC can provide, as such or via specific analysis methods, a full thermodynamic characterization of these nanomicelles, including their critical micellar concentration, micelle aggregation number, degree of counterion binding, Gibbs free energy of micellization, and its enthalpic and entropic components.
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