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Chang JW, Armaou A, Rioux RM. Continuous Injection Isothermal Titration Calorimetry for In Situ Evaluation of Thermodynamic Binding Properties of Ligand-Receptor Binding Models. J Phys Chem B 2021; 125:8075-8087. [PMID: 34259524 DOI: 10.1021/acs.jpcb.1c01821] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We utilize a continuous injection approach (CIA) rather than the traditional incremental injection approach (IIA) to deliver ligand (or receptor) to the calorimeter cell to evaluate thermodynamic binding parameters for three common ligand-receptor binding models-single independent, competitive, and two independent binding sites-using isothermal titration calorimetry (ITC). A general mathematical expression for the binding isotherm for any binding stoichiometry under continuous delivery of ligand (or receptor) resulting in an analytical solution for the thermodynamic binding parameters is presented. The advantages of CIA include reduction in experimental time, estimation of thermodynamic binding parameter values, and automation of the experiment since thermodynamic parameters are estimated in situ. We demonstrate the inherent advantages of CIA over IIA for the three binding models. For the single independent site model, we utilized the binding of Ba2+ ions to ethylenediaminetetraacetic acid (EDTA), while competitive binding was captured by titration of Ca2+ ions into a buffered solution of Ba2+ and EDTA. We experimentally simulated a two independent binding site system by injecting Ca2+ into a solution of EDTA and 1,3-diaminopropane-N,N,N',N'-tetraacetic acid (DPTA). The results demonstrate estimation of thermodynamic parameters with greater confidence and simultaneous reduction in the experimental time of 83% and titrating reagent of 50%, as compared to IIA.
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Affiliation(s)
- Ji Woong Chang
- Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.,Department of Chemical Engineering, Kumoh National Institute of Technology, Gumi-si, Gyeongsangbuk-do 39177, South Korea
| | - Antonios Armaou
- Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.,Department of Mechanical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.,FORTH Institute of Chemical Engineering Sciences, Rio 26504, Greece
| | - Robert M Rioux
- Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.,Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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2
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Zhang N, Qi R, Li H, Guan B, Liu Y, Han Y, Wang Y. Interaction of phospholipid vesicles with gemini surfactants of different lysine spacer lengths. SOFT MATTER 2019; 15:9458-9467. [PMID: 31742300 DOI: 10.1039/c9sm02040c] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Peptide surfactants have shown many potential applications in biology and medicine; however, the mechanism of their interactions with biomembranes is still unclear. This work has studied the interactions of cationic peptide gemini surfactants based on lysine spacers (12-(Lys)n-12, n = 2, 4, and 6) with model biological membranes, which are represented by the vesicles separately formed by zwitterionic unsaturated phospholipid 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), anionic unsaturated phospholipid 1,2-dioleoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (DOPG, sodium salt) and the DOPC/DOPG (1 : 1) mixture. The experiment results show that the presence of negatively charged DOPG slightly affects the interaction manners of 12-(Lys)n-12 with the vesicles, while the interaction of 12-(Lys)2-12 with the phospholipid vesicles is significantly different from that of 12-(Lys)4-12 and 12-(Lys)6-12 with the vesicles. The binding strength decreases in the order of 12-(Lys)4-12 > 12-(Lys)6-12 > 12-(Lys)2-12. The 12-(Lys)4-12 surfactant solubilizes the DOPC vesicles, and makes the DOPC molecules join the surfactant stiff fibers and changes them into long and flexible wormlike micelles, while the 12-(Lys)6-12 and 12-(Lys)2-12 aggregates are disassembled by the DOPC vesicles, and the surfactant molecules join the DOPC vesicles and convert the unilamellar vesicles into multilamellar vesicles. This work should be helpful in understanding the interaction of peptide surfactants with phospholipid membranes.
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Affiliation(s)
- Na Zhang
- Beijing National Laboratory for Molecular Science, CAS Key Laboratory of Colloid, Interface and Chemical Thermodynamics, CAS Research/Education Center for Excellence in Molecular Sciences, and Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China. and University of Chinese Academy of Sciences, Beijing 100049, China
| | - Ruilian Qi
- Beijing National Laboratory for Molecular Science, CAS Key Laboratory of Colloid, Interface and Chemical Thermodynamics, CAS Research/Education Center for Excellence in Molecular Sciences, and Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China. and University of Chinese Academy of Sciences, Beijing 100049, China
| | - Haofei Li
- Beijing National Laboratory for Molecular Science, CAS Key Laboratory of Colloid, Interface and Chemical Thermodynamics, CAS Research/Education Center for Excellence in Molecular Sciences, and Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China. and University of Chinese Academy of Sciences, Beijing 100049, China
| | - Bo Guan
- Analysis and Test Center, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Yang Liu
- Analysis and Test Center, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Yuchun Han
- Beijing National Laboratory for Molecular Science, CAS Key Laboratory of Colloid, Interface and Chemical Thermodynamics, CAS Research/Education Center for Excellence in Molecular Sciences, and Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
| | - Yilin Wang
- Beijing National Laboratory for Molecular Science, CAS Key Laboratory of Colloid, Interface and Chemical Thermodynamics, CAS Research/Education Center for Excellence in Molecular Sciences, and Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China. and University of Chinese Academy of Sciences, Beijing 100049, China
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3
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Alniss HY, Witzel II, Semreen MH, Panda PK, Mishra YK, Ahuja R, Parkinson JA. Investigation of the Factors That Dictate the Preferred Orientation of Lexitropsins in the Minor Groove of DNA. J Med Chem 2019; 62:10423-10440. [DOI: 10.1021/acs.jmedchem.9b01534] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Hasan Y. Alniss
- College of Pharmacy, University of Sharjah, P.O. Box 27272, Sharjah, United Arab Emirates
- Sharjah Institute for Medical Research, University of Sharjah, P.O. Box 27272, Sharjah, United Arab Emirates
| | - Ini-Isabée Witzel
- Core Technology Platform, New York University of Abu Dhabi, P.O. Box 129188, Saadiyat Island, Abu Dhabi, United Arab Emirates
| | - Mohammad H. Semreen
- College of Pharmacy, University of Sharjah, P.O. Box 27272, Sharjah, United Arab Emirates
- Sharjah Institute for Medical Research, University of Sharjah, P.O. Box 27272, Sharjah, United Arab Emirates
| | - Pritam Kumar Panda
- Department of Physics and Astronomy, Uppsala University, Box 516, SE-75120, Uppsala Sweden
| | - Yogendra Kumar Mishra
- Functional Nanomaterials, Institute for Materials Science, Kiel University, Kaiserstraße 2, D-24143 Kiel, Germany
| | - Rajeev Ahuja
- Department of Physics and Astronomy, Uppsala University, Box 516, SE-75120, Uppsala Sweden
- Department of Materials and Engineering, Royal Institute of Technology (KTH), SE-10044 Stockholm Sweden
| | - John A. Parkinson
- WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow G1 1XL, United Kingdom
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4
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Limo MJ, Sola-Rabada A, Boix E, Thota V, Westcott ZC, Puddu V, Perry CC. Interactions between Metal Oxides and Biomolecules: from Fundamental Understanding to Applications. Chem Rev 2018; 118:11118-11193. [PMID: 30362737 DOI: 10.1021/acs.chemrev.7b00660] [Citation(s) in RCA: 106] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Metallo-oxide (MO)-based bioinorganic nanocomposites promise unique structures, physicochemical properties, and novel biochemical functionalities, and within the past decade, investment in research on materials such as ZnO, TiO2, SiO2, and GeO2 has significantly increased. Besides traditional approaches, the synthesis, shaping, structural patterning, and postprocessing chemical functionalization of the materials surface is inspired by strategies which mimic processes in nature. Would such materials deliver new technologies? Answering this question requires the merging of historical knowledge and current research from different fields of science. Practically, we need an effective defragmentation of the research area. From our perspective, the superficial accounting of material properties, chemistry of the surfaces, and the behavior of biomolecules next to such surfaces is a problem. This is particularly of concern when we wish to bridge between technologies in vitro and biotechnologies in vivo. Further, besides the potential practical technological efficiency and advantages such materials might exhibit, we have to consider the wider long-term implications of material stability and toxicity. In this contribution, we present a critical review of recent advances in the chemistry and engineering of MO-based biocomposites, highlighting the role of interactions at the interface and the techniques by which these can be studied. At the end of the article, we outline the challenges which hamper progress in research and extrapolate to developing and promising directions including additive manufacturing and synthetic biology that could benefit from molecular level understanding of interactions occurring between inanimate (abiotic) and living (biotic) materials.
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Affiliation(s)
- Marion J Limo
- Interdisciplinary Biomedical Research Centre, School of Science and Technology , Nottingham Trent University , Clifton Lane, Nottingham NG11 8NS , United Kingdom.,Interface and Surface Analysis Centre, School of Pharmacy , University of Nottingham , University Park, Nottingham NG7 2RD , United Kingdom
| | - Anna Sola-Rabada
- Interdisciplinary Biomedical Research Centre, School of Science and Technology , Nottingham Trent University , Clifton Lane, Nottingham NG11 8NS , United Kingdom
| | - Estefania Boix
- Interdisciplinary Biomedical Research Centre, School of Science and Technology , Nottingham Trent University , Clifton Lane, Nottingham NG11 8NS , United Kingdom.,Department of Bioproducts and Biosystems , Aalto University , P.O. Box 16100, FI-00076 Aalto , Finland
| | - Veeranjaneyulu Thota
- Interdisciplinary Biomedical Research Centre, School of Science and Technology , Nottingham Trent University , Clifton Lane, Nottingham NG11 8NS , United Kingdom
| | - Zayd C Westcott
- Interdisciplinary Biomedical Research Centre, School of Science and Technology , Nottingham Trent University , Clifton Lane, Nottingham NG11 8NS , United Kingdom
| | - Valeria Puddu
- Interdisciplinary Biomedical Research Centre, School of Science and Technology , Nottingham Trent University , Clifton Lane, Nottingham NG11 8NS , United Kingdom
| | - Carole C Perry
- Interdisciplinary Biomedical Research Centre, School of Science and Technology , Nottingham Trent University , Clifton Lane, Nottingham NG11 8NS , United Kingdom
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5
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Affiliation(s)
- Hasan Y. Alniss
- Department of Medicinal Chemistry, College of Pharmacy, University of Sharjah, P.O. Box 27272, Sharjah, United Arab Emirates
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6
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Affiliation(s)
- Liora Werber
- Department of Chemistry and the Institute of Nanotechnology; Bar-Ilan University; Ramat Gan Israel
| | - Yitzhak Mastai
- Department of Chemistry and the Institute of Nanotechnology; Bar-Ilan University; Ramat Gan Israel
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Falconer RJ. Applications of isothermal titration calorimetry - the research and technical developments from 2011 to 2015. J Mol Recognit 2016; 29:504-15. [PMID: 27221459 DOI: 10.1002/jmr.2550] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Revised: 04/05/2016] [Accepted: 04/14/2016] [Indexed: 12/12/2022]
Abstract
Isothermal titration calorimetry is a widely used biophysical technique for studying the formation or dissociation of molecular complexes. Over the last 5 years, much work has been published on the interpretation of isothermal titration calorimetry (ITC) data for single binding and multiple binding sites. As over 80% of ITC papers are on macromolecules of biological origin, this interpretation is challenging. Some researchers have attempted to link the thermodynamics constants to events at the molecular level. This review highlights work carried out using binding sites characterized using x-ray crystallography techniques that allow speculation about individual bond formation and the displacement of individual water molecules during ligand binding and link these events to the thermodynamic constants for binding. The review also considers research conducted with synthetic binding partners where specific binding events like anion-π and π-π interactions were studied. The revival of assays that enable both thermodynamic and kinetic information to be collected from ITC data is highlighted. Lastly, published criticism of ITC research from a physical chemistry perspective is appraised and practical advice provided for researchers unfamiliar with thermodynamics and its interpretation. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Robert J Falconer
- Department of Chemical and Biological Engineering, ChELSI Institute, University of Sheffield, Sheffield, S1 3JD, UK.
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Koler M, Frank V, Amartely H, Friedler A, Vaknin A. Dynamic Clustering of the Bacterial Sensory Kinase BaeS. PLoS One 2016; 11:e0150349. [PMID: 26950881 PMCID: PMC4780735 DOI: 10.1371/journal.pone.0150349] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 02/14/2016] [Indexed: 11/29/2022] Open
Abstract
Several bacterial sensory-kinase receptors form clusters on the cell membrane. However, the dynamics of sensory-kinase clustering are largely unclear. Using measurements of fluorescence anisotropy and time-lapse imaging of Escherichia coli cells, we demonstrate that copper ions trigger self-association of BaeS receptors and lead to rapid formation of clusters, which can be reversibly dispersed by a metal chelator. Copper ions did not trigger self-association of other fluorescently tagged sensory kinases, and other divalent metal ions could not elicit self-association of BaeS. The histidine residues in the BaeS periplasmic domain are essential for copper binding in vitro and are important for the copper-induced BaeS responses in vivo. BaeS clustering was triggered also under conditions that directly triggered BaeS-dependent transcriptional responses. Thus, clustering of sensory kinase receptors can be dynamic and context dependent and can be triggered by specific environmental cues.
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Affiliation(s)
- Moriah Koler
- The Racah Institute of Physics, The Hebrew University of Jerusalem, Safra Campus, Givat Ram, Jerusalem, 91904, Israel
| | - Vered Frank
- The Racah Institute of Physics, The Hebrew University of Jerusalem, Safra Campus, Givat Ram, Jerusalem, 91904, Israel
| | - Hadar Amartely
- The Institute of Chemistry, The Hebrew University of Jerusalem, Safra Campus, Givat Ram, Jerusalem, 91904, Israel
| | - Assaf Friedler
- The Institute of Chemistry, The Hebrew University of Jerusalem, Safra Campus, Givat Ram, Jerusalem, 91904, Israel
| | - Ady Vaknin
- The Racah Institute of Physics, The Hebrew University of Jerusalem, Safra Campus, Givat Ram, Jerusalem, 91904, Israel
- * E-mail:
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Limo MJ, Perry CC. Thermodynamic Study of Interactions Between ZnO and ZnO Binding Peptides Using Isothermal Titration Calorimetry. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:6814-6822. [PMID: 26037020 DOI: 10.1021/acs.langmuir.5b01347] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
While material-specific peptide binding sequences have been identified using a combination of combinatorial methods and computational modeling tools, a deep molecular level understanding of the fundamental principles through which these interactions occur and in some instances modify the morphology of inorganic materials is far from being fully realized. Understanding the thermodynamic changes that occur during peptide-inorganic interactions and correlating these to structural modifications of the inorganic materials could be the key to achieving and mastering control over material formation processes. This study is a detailed investigation applying isothermal titration calorimetry (ITC) to directly probe thermodynamic changes that occur during interaction of ZnO binding peptides (ZnO-BPs) and ZnO. The ZnO-BPs used are reported sequences G-12 (GLHVMHKVAPPR), GT-16 (GLHVMHKVAPPR-GGGC), and alanine mutants of G-12 (G-12A6, G-12A11, and G-12A12) whose interaction with ZnO during solution synthesis studies have been extensively investigated. The interactions of the ZnO-BPs with ZnO yielded biphasic isotherms comprising both an endothermic and an exothermic event. Qualitative differences were observed in the isothermal profiles of the different peptides and ZnO particles studied. Measured ΔG values were between -6 and -8.5 kcal/mol, and high adsorption affinity values indicated the occurrence of favorable ZnO-BP-ZnO interactions. ITC has great potential in its use to understand peptide-inorganic interactions, and with continued development, the knowledge gained may be instrumental for simplification of selection processes of organic molecules for the advancement of material synthesis and design.
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Affiliation(s)
- Marion J Limo
- Biomolecular and Materials Interface Research Group, Interdisciplinary Biomedical Research Centre, School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham NG11 8NS, United Kingdom
| | - Carole C Perry
- Biomolecular and Materials Interface Research Group, Interdisciplinary Biomedical Research Centre, School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham NG11 8NS, United Kingdom
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Fang B, Zhang M, Tian M, Jiang L, Guo HY, Ren FZ. Bovine lactoferrin binds oleic acid to form an anti-tumor complex similar to HAMLET. Biochim Biophys Acta Mol Cell Biol Lipids 2014; 1841:535-43. [DOI: 10.1016/j.bbalip.2013.12.008] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Revised: 12/08/2013] [Accepted: 12/14/2013] [Indexed: 10/25/2022]
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11
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Moschetta EG, Gans KM, Rioux RM. Characterization of sites of different thermodynamic affinities on the same metal center via isothermal titration calorimetry. J Catal 2013. [DOI: 10.1016/j.jcat.2013.02.020] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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12
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Campagne S, Muller I, Milon A, Gervais V. Towards the classification of DYT6 dystonia mutants in the DNA-binding domain of THAP1. Nucleic Acids Res 2012; 40:9927-40. [PMID: 22844099 PMCID: PMC3479173 DOI: 10.1093/nar/gks703] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The transcription factor THAP1 (THanatos Associated Protein 1) has emerged recently as the cause of DYT6 primary dystonia, a type of rare, familial and mostly early-onset syndrome that leads to involuntary muscle contractions. Many of the mutations described in the DYT6 patients fall within the sequence-specific DNA-binding domain (THAP domain) of THAP1 and are believed to negatively affect DNA binding. Here, we have used an integrated approach combining spectroscopic (NMR, fluorescence, DSF) and calorimetric (ITC) methods to evaluate the effect of missense mutations, within the THAP domain, on the structure, stability and DNA binding. Our study demonstrates that none of the mutations investigated failed to bind DNA and some of them even bind DNA stronger than the wild-type protein. However, some mutations could alter DNA-binding specificity. Furthermore, the most striking effect is the decrease of stability observed for mutations at positions affecting the zinc coordination, the hydrophobic core or the C-terminal AVPTIF motif, with unfolding temperatures ranging from 46°C for the wild-type to below 37°C for two mutations. These findings suggest that reduction in population of folded protein under physiological conditions could also account for the disease.
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Affiliation(s)
- Sébastien Campagne
- CNRS; IPBS (Institut de Pharmacologie et de Biologie Structurale); 205 route de Narbonne, BP64182, F-31077 Toulouse, France
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Ghai R, Falconer RJ, Collins BM. Applications of isothermal titration calorimetry in pure and applied research--survey of the literature from 2010. J Mol Recognit 2012; 25:32-52. [PMID: 22213449 DOI: 10.1002/jmr.1167] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Isothermal titration calorimetry (ITC) is a biophysical technique for measuring the formation and dissociation of molecular complexes and has become an invaluable tool in many branches of science from cell biology to food chemistry. By measuring the heat absorbed or released during bond formation, ITC provides accurate, rapid, and label-free measurement of the thermodynamics of molecular interactions. In this review, we survey the recent literature reporting the use of ITC and have highlighted a number of interesting studies that provide a flavour of the diverse systems to which ITC can be applied. These include measurements of protein-protein and protein-membrane interactions required for macromolecular assembly, analysis of enzyme kinetics, experimental validation of molecular dynamics simulations, and even in manufacturing applications such as food science. Some highlights include studies of the biological complex formed by Staphylococcus aureus enterotoxin C3 and the murine T-cell receptor, the mechanism of membrane association of the Parkinson's disease-associated protein α-synuclein, and the role of non-specific tannin-protein interactions in the quality of different beverages. Recent developments in automation are overcoming limitations on throughput imposed by previous manual procedures and promise to greatly extend usefulness of ITC in the future. We also attempt to impart some practical advice for getting the most out of ITC data for those researchers less familiar with the method.
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Affiliation(s)
- Rajesh Ghai
- Institute for Molecular Bioscience (IMB), University of Queensland, St. Lucia, Queensland, 4072, Australia
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15
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Freiburger LA, Mittermaier AK, Auclair K. Collecting variable-concentration isothermal titration calorimetry datasets in order to determine binding mechanisms. J Vis Exp 2011:2529. [PMID: 21505408 DOI: 10.3791/2529] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Isothermal titration calorimetry (ITC) is commonly used to determine the thermodynamic parameters associated with the binding of a ligand to a host macromolecule. ITC has some advantages over common spectroscopic approaches for studying host/ligand interactions. For example, the heat released or absorbed when the two components interact is directly measured and does not require any exogenous reporters. Thus the binding enthalpy and the association constant (Ka) are directly obtained from ITC data, and can be used to compute the entropic contribution. Moreover, the shape of the isotherm is dependent on the c-value and the mechanistic model involved. The c-value is defined as c = n[P]tKa, where [P]t is the protein concentration, and n is the number of ligand binding sites within the host. In many cases, multiple binding sites for a given ligand are non-equivalent and ITC allows the characterization of the thermodynamic binding parameters for each individual binding site. This however requires that the correct binding model be used. This choice can be problematic if different models can fit the same experimental data. We have previously shown that this problem can be circumvented by performing experiments at several c-values. The multiple isotherms obtained at different c-values are fit simultaneously to separate models. The correct model is next identified based on the goodness of fit across the entire variable-c dataset. This process is applied here to the aminoglycoside resistance-causing enzyme aminoglycoside N-6'-acetyltransferase-Ii (AAC(6')-Ii). Although our methodology is applicable to any system, the necessity of this strategy is better demonstrated with a macromolecule-ligand system showing allostery or cooperativity, and when different binding models provide essentially identical fits to the same data. To our knowledge, there are no such systems commercially available. AAC(6')-Ii, is a homo-dimer containing two active sites, showing cooperativity between the two subunits. However ITC data obtained at a single c-value can be fit equally well to at least two different models a two-sets-of-sites independent model and a two-site sequential (cooperative) model. Through varying the c-value as explained above, it was established that the correct binding model for AAC(6')-Ii is a two-site sequential binding model. Herein, we describe the steps that must be taken when performing ITC experiments in order to obtain datasets suitable for variable-c analyses.
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16
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Thermodynamic Study of the Binding of Mercury Ion to Human Growth Hormone at Different Temperatures. J SOLUTION CHEM 2011. [DOI: 10.1007/s10953-011-9668-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
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17
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Davies P, Wang X, Sarell CJ, Drewett A, Marken F, Viles JH, Brown DR. The synucleins are a family of redox-active copper binding proteins. Biochemistry 2010; 50:37-47. [PMID: 21117662 DOI: 10.1021/bi101582p] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Thermodynamic studies in conjunction with EPR confirm that α-synuclein, β-synuclein, and γ-synuclein bind copper(II) in a high affinity 1:1 stoichiometry. γ-Synuclein demonstrates the highest affinity, in the picomolar range, while α-synuclein and β-synuclein both bind copper(II) with nanomolar affinity. The copper center on all three proteins demonstrates reversible or partly reversible redox cycling. Various mutations show that the primary coordinating ligand for copper(II) is located within the N-terminal regions between residues 2-9. There is also a contribution from the C-terminus in conjunction with the histidine at position 50 in α-synuclein and position 65 in β-synuclein, although these regions appear to have little effect on overall coordination stability. These histidines and the C-terminus, however, appear to be critical to the redox engine of the proteins.
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Affiliation(s)
- Paul Davies
- Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath BA27AY, UK
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Edink E, Jansen C, Leurs R, de Esch IJ. The heat is on: thermodynamic analysis in fragment-based drug discovery. DRUG DISCOVERY TODAY. TECHNOLOGIES 2010; 7:e147-e202. [PMID: 24103770 DOI: 10.1016/j.ddtec.2010.12.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
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Abstract
Calorimetric measurements on biological systems from small molecules to whole organisms lead to a new conception of the nature of live matter that has profound consequences for our understanding of biology. The data show that the differences in Gibbs energy (ΔG) and enthalpy (ΔH) are near zero or negative and the difference in entropy (ΔS) is near zero between a random mixture of molecules and live matter of the same composition. A constant input of energy is required to maintain ion gradients, ATP production, and the other functions of living matter, but because cells are organized in a spontaneous process, no energy input is required to maintain the structure or organization of cells. Thus, the origin of life and evolution of complex life forms occurs by thermodynamically spontaneous processes, carbon-based life should be common throughout the universe, and because there is no energy cost, evolution can occur relatively rapidly.
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Bjelić S, Jelesarov I. A survey of the year 2007 literature on applications of isothermal titration calorimetry. J Mol Recognit 2008; 21:289-312. [PMID: 18729242 DOI: 10.1002/jmr.909] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Elucidation of the energetic principles of binding affinity and specificity is a central task in many branches of current sciences: biology, medicine, pharmacology, chemistry, material sciences, etc. In biomedical research, integral approaches combining structural information with in-solution biophysical data have proved to be a powerful way toward understanding the physical basis of vital cellular phenomena. Isothermal titration calorimetry (ITC) is a valuable experimental tool facilitating quantification of the thermodynamic parameters that characterize recognition processes involving biomacromolecules. The method provides access to all relevant thermodynamic information by performing a few experiments. In particular, ITC experiments allow to by-pass tedious and (rarely precise) procedures aimed at determining the changes in enthalpy and entropy upon binding by van't Hoff analysis. Notwithstanding limitations, ITC has now the reputation of being the "gold standard" and ITC data are widely used to validate theoretical predictions of thermodynamic parameters, as well as to benchmark the results of novel binding assays. In this paper, we discuss several publications from 2007 reporting ITC results. The focus is on applications in biologically oriented fields. We do not intend a comprehensive coverage of all newly accumulated information. Rather, we emphasize work which has captured our attention with originality and far-reaching analysis, or else has provided ideas for expanding the potential of the method.
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Affiliation(s)
- Sasa Bjelić
- Biochemisches Institut der Universität Zürich, Winterthurerstrasse 190, Zürich, Switzerland
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Liang Y. Applications of isothermal titration calorimetry in protein science. Acta Biochim Biophys Sin (Shanghai) 2008; 40:565-76. [PMID: 18604448 DOI: 10.1111/j.1745-7270.2008.00437.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
During the past decade, isothermal titration calorimetry (ITC) has developed from a specialist method for understanding molecular interactions and other biological processes within cells to a more robust, widely used method. Nowadays, ITC is used to investigate all types of protein interactions, including protein-protein interactions, protein-DNA/RNA interactions, protein-small molecule interactions and enzyme kinetics; it provides a direct route to the complete thermodynamic characterization of protein interactions. This review concentrates on the new applications of ITC in protein folding and misfolding, its traditional application in protein interactions, and an overview of what can be achieved in the field of protein science using this method and what developments are likely to occur in the near future. Also, this review discusses some new developments of ITC method in protein science, such as the reverse titration of ITC and the displacement method of ITC.
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Affiliation(s)
- Yi Liang
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, China.
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22
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Buurma NJ, Haq I. Calorimetric and spectroscopic studies of Hoechst 33258: self-association and binding to non-cognate DNA. J Mol Biol 2008; 381:607-21. [PMID: 18617189 DOI: 10.1016/j.jmb.2008.05.073] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2008] [Revised: 05/04/2008] [Accepted: 05/30/2008] [Indexed: 10/22/2022]
Abstract
Sequence and structure-specific molecular recognition of DNA by small molecules is an important goal in biophysical chemistry and drug discovery. Many candidate ligands possess flat aromatic surfaces and other molecular features that allow them to self-associate. In addition, non-specific binding to the target is a complicating feature of these interactions. Therefore, multiple equilibria are present and need to be accounted for in data analysis in order to obtain meaningful thermodynamic parameters. In order to address these issues we have systematically examined the bis-benzimidazole dye Hoechst 33258 (H33258) in terms of self-aggregation and binding to DNA oligonucleotides lacking any cognate minor groove A.T sites. This model system has been interrogated using isothermal titration calorimetry (ITC), circular dichroism (CD), fluorescence spectroscopy and pulsed gradient spin echo NMR. Three distinct binding events and ligand self-aggregation have been identified and, where possible, quantified. H33258 self-aggregation involves a step-wise aggregation mechanism, driven by stacking interactions. The DNA binding process includes two specific binding modes and non-specific DNA-templated H33258 stacking. We have written novel ITC data-fitting software (IC-ITC; freely available to the biophysics community), which simultaneously fits ligand aggregation and ligand-DNA binding. Here, this numerical analysis, which uses simulated annealing of complex calorimetric data representing multiple coupled equilibria, is described.
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Affiliation(s)
- Niklaas J Buurma
- Centre for Chemical Biology, The Department of Chemistry, The University of Sheffield, Dainton Building, Brook Hill, Sheffield, South Yorkshire, S3 7HF, UK
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Okhrimenko O, Jelesarov I. A survey of the year 2006 literature on applications of isothermal titration calorimetry. J Mol Recognit 2008; 21:1-19. [DOI: 10.1002/jmr.859] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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24
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Isothermal Titration Calorimetry: Experimental Design, Data Analysis, and Probing Macromolecule/Ligand Binding and Kinetic Interactions. Methods Cell Biol 2008; 84:79-113. [DOI: 10.1016/s0091-679x(07)84004-0] [Citation(s) in RCA: 339] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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25
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Strategies for label-free optical detection. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2007; 109:395-432. [PMID: 17999039 DOI: 10.1007/10_2007_076] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
A large number of methods using direct detection with label-free systems are known. They compete with the well-introduced fluorescence-based methods. However, recent applications take advantage of label-free detection in protein-protein interactions, high-throughput screening, and high-content screening. These new applications require new strategies for biosensors. It becomes more and more obvious that neither the transduction principle nor the recognition elements for the biomolecular interaction process alone determine the quality of the biosensor. Accordingly, the biosensor system has to be considered as a whole. This chapter focuses on strategies to optimize the detection platform and the biomolecular recognition layer. It concentrates on direct detection methods, with special focus on optical transduction. Since even this restriction still leaves a large number of methods, only microrefractometric and microreflectometric methods using planar transducers have been selected for a detailed description and a listing of applications. However, since many review articles on the physical principles exist, the description is kept short. Other methods are just mentioned in brief and for comparison. The outlook and the applications demonstrate the future perspectives of direct optical detection in bioanalytics.
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26
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Buurma NJ, Haq I. Advances in the analysis of isothermal titration calorimetry data for ligand-DNA interactions. Methods 2007; 42:162-72. [PMID: 17472898 DOI: 10.1016/j.ymeth.2007.01.010] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2006] [Revised: 12/20/2006] [Accepted: 01/08/2007] [Indexed: 11/22/2022] Open
Abstract
Isothermal titration calorimetry (ITC) is a well established technique for the study of biological interactions. The strength of ITC is that it directly measures enthalpy changes associated with interactions. Experiments can also yield binding isotherms allowing quantification of equilibrium binding constants, hence an almost complete thermodynamic profile can be established. Principles and application of ITC have been well documented over recent years, experimentally the technique is simple to use and in ideal scenarios data analysis is trivial. However, ITC experiments can be designed such that previously inaccessible parameters can be evaluated. We outline some of these advances, including (1) exploiting different experimental conditions; (2) low affinity systems; (3) high affinity systems and displacement assays. In addition we ask the question: What if data cannot be fit using the fitting functions incorporated in the data-analysis software that came with your ITC? Examples where such data might be generated include systems following non 1:n binding patterns and systems where binding is coupled to other events such as ligand dissociation. Models dealing with such data are now appearing in literature and we summarise examples relevant for the study of ligand-DNA interactions.
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Lapitsky Y, Parikh M, Kaler EW. Calorimetric Determination of Surfactant/Polyelectrolyte Binding Isotherms. J Phys Chem B 2007; 111:8379-87. [PMID: 17388496 DOI: 10.1021/jp0678958] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Mixing of oppositely charged surfactants and polyelectrolytes in aqueous solutions leads to cooperative surfactant adsorption onto the polyelectrolyte chains. Experimental determination of surfactant/polyelectrolyte binding isotherms is usually done using custom-built surfactant-ion-specific electrodes. As an alternative, we present an indirect isotherm approximation method that uses conventional isothermal titration calorimetry (ITC). The calorimetric data is fitted to the two-binding-state Satake-Yang adsorption model, which quantifies the extent of binding in terms of the binding constant (Ku) and the cooperativity parameter (u). This approach is investigated using two surfactant/polyelectrolyte mixtures: sodium perfluorooctanoate (FC7) and N,N,N-trimethylammonium derivatized hydroxyethyl cellulose (UCARE Polymer JR-400), whose binding behavior follows the Satake-Yang model, and dodecyltrimethylammonium bromide (DTAB) and poly(styrenesulfonate) (NaPSS), whose behavior deviates dramatically from the Satake-Yang model. These studies demonstrate that, in order to apply the indirect ITC method of binding isotherm determination, the surfactant/polyelectrolyte adsorption process must have no more than two dominant binding states. Thus, the technique works well for the FC7/JR-400 mixture. It fails in the case of the DTAB/NaPSS adsorption, but its mode of failure offers insight into the multiple-binding-state adsorption mechanism.
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Affiliation(s)
- Yakov Lapitsky
- Center for Molecular and Engineering Thermodynamics, Department of Chemical Engineering, University of Delaware, Newark, Delaware 19716, USA.
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Isin EM, Guengerich FP. Multiple Sequential Steps Involved in the Binding of Inhibitors to Cytochrome P450 3A4. J Biol Chem 2007; 282:6863-74. [PMID: 17200113 DOI: 10.1074/jbc.m610346200] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cytochrome P450 (P450) 3A4 is an extensively studied human enzyme involved in the metabolism of >50% of drugs. The mechanism of the observed homotropic and heterotropic cooperativity in P450 3A4-catalyzed oxidations is not well understood, and together with the cooperative behavior, a detailed understanding of interaction of drug inhibitors with P450 3A4 is important in predicting clinical drug-drug interactions. The interactions of P450 3A4 with several structurally diverse inhibitors were investigated using both kinetic and thermodynamic approaches to resolve the steps involved in binding of these ligands. The results of pre-steady-state absorbance and fluorescence experiments demonstrate that inhibitor binding is clearly a multistep process, even more complex than the binding of substrates. Based on spectrophotometric equilibrium binding titrations as well as isothermal titration calorimetry experiments, the stoichiometry of binding appears to be 1:1 in the concentration ranges studied. Using a sequential-mixing stopped-flow approach, we were also able to show that the observed multiphasic binding kinetics is the result of sequential events as opposed to the existence of multiple enzyme populations in dynamic equilibrium that interact with ligands at different rates. We propose a three-step minimal model for inhibitor binding, developed with kinetic simulations, consistent with our previously reported model for the binding of substrates, although it is possible that even more steps are involved.
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Affiliation(s)
- Emre M Isin
- Department of Biochemistry and Center in Molecular Toxicology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146, USA
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29
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Ababou A, Ladbury JE. Survey of the year 2005: literature on applications of isothermal titration calorimetry. J Mol Recognit 2007; 20:4-14. [PMID: 17006876 DOI: 10.1002/jmr.803] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Isothermal titration calorimetry (ITC) can provide a full thermodynamic characterization of an interaction. Its usage does not suffer from constraints of molecular size, shape or chemical constitution. Neither is there any need for chemical modification or attachment to solid support. This ease of use has made it an invaluable instrumental resource and led to its appearance in many laboratories. Despite this, the value of the thermodynamic parameterization has, only quite recently, become widely appreciated. Although our understanding of the correlation between thermodynamic data and structural details continues to be somewhat naïve, a large number of publications have begun to improve the situation. In this overview of the literature for 2005, we have attempted to highlight works of interest and novelty. Furthermore, we draw attention to those works which we feel have provided a route to better analysis and increased our ability to understand the meaning of thermodynamic change on binding.
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Affiliation(s)
- Adessamad Ababou
- Department of Biochemistry and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK
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30
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Sun DZ, Li L, Qiu XM, Liu M, Yin BL. Cyclodextrins Binding to Paeonol and Two of Its Isomers in Aqueous Solution. Isothermal Titration Calorimetry and 1H NMR Investigations of Molecular Recognition. J SOLUTION CHEM 2006. [DOI: 10.1007/s10953-006-9075-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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31
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Lykken GL, Chen G, Brutinel ED, Chen L, Yahr TL. Characterization of ExsC and ExsD self-association and heterocomplex formation. J Bacteriol 2006; 188:6832-40. [PMID: 16980486 PMCID: PMC1595525 DOI: 10.1128/jb.00884-06] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Expression of the Pseudomonas aeruginosa type III secretion system (T3SS) is induced by calcium depletion and is positively regulated by the ExsA transcriptional activator and negatively regulated by the ExsD antiactivator. Under conditions permissive for expression of the T3SS, the negative regulatory activity of ExsD is antagonized by a direct binding interaction with ExsC. In the present study, the ExsC-ExsD binding interaction was characterized. Individually, both ExsC and ExsD form self-associated complexes, as judged by bacterial monohybrid and gel filtration experiments. A mixture of purified ExsC and ExsD readily formed a complex that elutes from gel filtration medium as a single included peak. The calculated molecular weight of the ExsC-ExsD complex is consistent with a complex containing multiple copies of ExsC and ExsD. Isothermic titration calorimetry experiments found formation of the ExsC-ExsD complex to be thermodynamically favorable, with a Kd of approximately 18 nM and a likely binding ratio of 1:1. To identify amino acid residues important for the regulatory activities of ExsC and ExsD, self-association, and complex formation, charged-cluster mutagenesis was performed. Two of the resulting ExsD charged-cluster mutants (DM2 and DM3) demonstrated a hyperrepressive phenotype for expression of the T3SS. By two-hybrid and copurification assays, the DM3 mutant was found to be impaired in its interaction with ExsC. This finding demonstrates that the binding of ExsC to ExsD is required for transcriptional induction of the T3SS under calcium-limiting growth conditions.
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Affiliation(s)
- Guinevere L Lykken
- Department of Microbiology, University of Iowa, Iowa City, IA 52242-1101, USA
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32
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Isin EM, Guengerich FP. Kinetics and Thermodynamics of Ligand Binding by Cytochrome P450 3A4. J Biol Chem 2006; 281:9127-36. [PMID: 16467307 DOI: 10.1074/jbc.m511375200] [Citation(s) in RCA: 124] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cytochrome P450 (P450) 3A4, the major catalyst involved in human drug oxidation, displays substrate- and reaction-dependent homotropic and heterotropic cooperative behavior. Although several models have been proposed, these mainly rely on steady-state kinetics and do not provide information on the contribution of the individual steps of P450 catalytic cycle to the observed cooperativity. In this work, we focused on the kinetics of substrate binding, and the fluorescent properties of bromocriptine and alpha-naphthoflavone allowed analysis of an initial ligand-P450 3A4 interaction that does not cause a perturbation of the heme spectrum. The binding stoichiometry for bromocriptine was determined to be unity using isothermal titration calorimetry and equilibrium dialysis methods, suggesting that the ligand bound to the peripheral site during the initial encounter dissociates subsequently. A three-step substrate binding model is proposed, based on absorbance and fluorescence stopped-flow kinetic data and equilibrium binding data obtained with bromocriptine, and evaluated using kinetic modeling. The results are consistent with the substrate molecule binding at a site peripheral to the active site and subsequently moving toward the active site to bind to the heme and resulting in a low to high spin iron shift. The last step is attributed to a conformational change in the enzyme active site. The later steps of binding were shown to have rate constants comparable with the subsequent steps of the catalytic cycle. The P450 3A4 binding process is more complex than a two-state system, and the overlap of rates of some of the events with subsequent steps is proposed to underlie the observed cooperativity.
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Affiliation(s)
- Emre M Isin
- Department of Biochemistry and Center in Molecular Toxicology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146, USA
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Xiang J, Fan JB, Chen N, Chen J, Liang Y. Interaction of cellulase with sodium dodecyl sulfate at critical micelle concentration level. Colloids Surf B Biointerfaces 2006; 49:175-80. [PMID: 16632334 DOI: 10.1016/j.colsurfb.2006.03.015] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2005] [Revised: 03/13/2006] [Accepted: 03/13/2006] [Indexed: 11/25/2022]
Abstract
The interactions between Trichoderma reesei cellulase and an anionic surfactant, sodium dodecyl sulfate (SDS), at critical micelle concentration level have been investigated using isothermal titration calorimetry, fluorescence spectroscopy, and circular dichroism. SDS micelles have dual interactions with cellulase: electrostatic at first and then hydrophobic interactions. When the concentration of SDS is smaller than 45.0mM, SDS micelles cause a partial loss in the hydrolytic activity together with a steep decrease in the alpha-helical content of cellulase. With further increasing the concentration of SDS, however, a re-formation of the alpha-helical structure and a partial recovery of the hydrolytic activity of cellulase induced by SDS micelles are observed. Taken together, these results indicate that SDS micelles exert dual effects on cellulase through binding as both a denaturant and a recovery reagent.
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Affiliation(s)
- Jin Xiang
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, China
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34
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Chavelas EA, Zubillaga RA, Pulido NO, García-Hernández E. Multithermal titration calorimetry: A rapid method to determine binding heat capacities. Biophys Chem 2006; 120:10-4. [PMID: 16246484 DOI: 10.1016/j.bpc.2005.09.022] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2005] [Revised: 09/19/2005] [Accepted: 09/20/2005] [Indexed: 10/25/2022]
Abstract
Herein a new method that allows binding DeltaCp to be determined with a single experiment is presented. Multithermal titration calorimetry (MTC) is a simple extension of isothermal titration calorimetry (ITC) that explicitly takes into account the thermal dependences of DeltaH and the binding constant. Experimentally, this is accomplished by performing a single stepwise titration with ITC equipment, allowing temperature re-adjustments of the system at intermediate states of the titration process. Thus, from the resulting multitherm, DeltaCp can also be determined. The experimental feasibility of MTC was tested by using the well-characterized lysozyme-chitotriose complex as a model system.
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Affiliation(s)
- Eneas A Chavelas
- Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Cd. Universitaria, México D.F., México 04510
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Xu H, Liang Y, Zhang P, Du F, Zhou BR, Wu J, Liu JH, Liu ZG, Ji LN. Biophysical studies of a ruthenium(II) polypyridyl complex binding to DNA and RNA prove that nucleic acid structure has significant effects on binding behaviors. J Biol Inorg Chem 2005; 10:529-38. [PMID: 16091935 PMCID: PMC7087908 DOI: 10.1007/s00775-005-0007-3] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2005] [Accepted: 07/03/2005] [Indexed: 11/22/2022]
Abstract
The interactions of a metal complex [Ru(phen)(2)PMIP](2+) {Ru=ruthenium, phen=1,10-phenanthroline, PMIP=2-(4-methylphenyl)imidazo[4,5-f]1,10-phenanthroline} with yeast tRNA and calf thymus DNA (CT DNA) have been investigated comparatively by UV-vis spectroscopy, fluorescence spectroscopy, viscosity measurements, isothermal titration calorimetry (ITC), as well as equilibrium dialysis and circular dichroism (CD). Spectroscopic studies together with ITC and viscosity measurements indicate that both binding modes of the Ru(II) polypyridyl complex to yeast tRNA and CT DNA are intercalation and yeast tRNA binding of the complex is stronger than CT DNA binding. ITC experiments show that the interaction of the complex with yeast tRNA is driven by a moderately favorable enthalpy decrease in combination with a moderately favorable entropy increase, while the binding of the complex to CT DNA is driven by a large favorable enthalpy decrease with a less favorable entropy increase. The results from equilibrium dialysis and CD suggest that both interactions are enantioselective and the Delta enantiomer of the complex may bind more favorably to both yeast tRNA and CT DNA than the Lambda enantiomer does, and that the complex is a better candidate for an enantioselective binder to yeast tRNA than to CT DNA. Taken together, these results indicate that the structures of nucleic acids have significant effects on the binding behaviors of metal complexes.
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Affiliation(s)
- Hong Xu
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, 430072 Wuhan, China
- Department of Chemistry and Biology, Normal College, Shenzhen University, 518060 Shenzhen, China
- State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing, 210093 China
| | - Yi Liang
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, 430072 Wuhan, China
| | - Peng Zhang
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, 430072 Wuhan, China
| | - Fen Du
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, 430072 Wuhan, China
| | - Bing-Rui Zhou
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, 430072 Wuhan, China
| | - Jun Wu
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, 430072 Wuhan, China
| | - Jian-Hong Liu
- Department of Chemistry and Biology, Normal College, Shenzhen University, 518060 Shenzhen, China
| | - Zhi-Gang Liu
- Department of Chemistry and Biology, Normal College, Shenzhen University, 518060 Shenzhen, China
| | - Liang-Nian Ji
- Key Laboratory of Gene Engineering of Ministry of Education, Zhongshan University, Guangzhou, 510275 China
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Hong X, Jian-Hong L, Zhi-Gang L, Yi L, Peng Z, Fen D, Bing-Rui Z, Liang-Nian J. Interaction of Ru(II) Complex with Yeast tRNA Studied by Isothermal Titration Calorimetry. CHINESE J CHEM 2005. [DOI: 10.1002/cjoc.200590659] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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37
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Winter HC, Oscarson S, Slättegård R, Tian M, Goldstein IJ. Banana lectin is unique in its recognition of the reducing unit of 3-O-β-glucosyl/mannosyl disaccharides: a calorimetric study. Glycobiology 2005; 15:1043-50. [PMID: 15888634 DOI: 10.1093/glycob/cwi074] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The binding of banana lectin (BanLec) to laminaribiose (Glcbeta1,3Glc) and a series of novel synthetic analogues was measured by titration calorimetry to assess the contribution of the hydroxyl groups of the reducing glycosyl moiety and its 3-O-beta-substituent to binding. Key areas of interaction involved the 1, 2, and 6 positions of the reducing-terminal hexose unit. The alpha-anomeric configuration of the reducing hexose was strongly favored over the beta-anomer. The 2-hydroxyl in the axial position (mannose) also enhanced binding, whereas the 6-hydroxymethyl group was essential, because xylopyranose in the reducing position was inactive. The 3-O-beta-glucosyl unit of methyl alpha-laminaribioside could be replaced by any of its monodeoxy derivatives. However, the 4'-deoxy derivative or axial hydroxy (galactosyl) substitution was somewhat detrimental to binding. 3-O-substitution with the (S)tetrahydropyranyl ring or a benzyl group had similar effect as 4'-deoxyglucosyl substitution. Surprisingly, p-nitrobenzyl or beta-xylosyl 3-O-substitution greatly enhanced binding of the reducing glucosyl or mannosyl derivative. Chemical syntheses of a number of novel disaccharides and analogues prepared for this study are described.
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Affiliation(s)
- Harry C Winter
- Department of Biological Chemistry, The University of Michigan Medical School, Ann Arbor, MI, USA
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Ababou A, Ladbury JE. Survey of the year 2004: literature on applications of isothermal titration calorimetry. J Mol Recognit 2005; 19:79-89. [PMID: 16220545 DOI: 10.1002/jmr.750] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The market for commercially available isothermal titration calorimeters continues to grow as new applications and methodologies are developed. Concomitantly the number of users (and abusers) increases dramatically, resulting in a steady increase in the number of publications in which isothermal titration calorimetry (ITC) plays a role. In the present review, we will focus on areas where ITC is making a significant contribution and will highlight some interesting applications of the technique. This overview of papers published in 2004 also discusses current issues of interest in the development of ITC as a tool of choice in the determination of the thermodynamics of molecular recognition and interaction.
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Affiliation(s)
- Abdessamad Ababou
- Department of Biochemistry and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK
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