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Microbial Biotechnology Mar 2008Almost any process in life is accompanied by heat changes which can be monitored by isothermal titration calorimetry (ITC) and differential scanning calorimetry (DSC).... (Review)
Review
Almost any process in life is accompanied by heat changes which can be monitored by isothermal titration calorimetry (ITC) and differential scanning calorimetry (DSC). Both techniques are now established tools in fundamental research but over the last decade a clear tendency towards more problem-driven applications is noted. This review aims at summarizing these problem-oriented applications of microcalorimetry and the solutions both techniques can provide to problems in biotechnology. The biotechnological issues to which microcalorimetry has been successfully applied are as diverse as rational drug design, overcoming drug resistance, optimization of long-term stability of proteins, estimation of the bioavailability of drugs, control of complex pharmaceutical products or the optimization of gene delivery efficiency. The main limitation of microcalorimetry, which is the relatively large amounts of sample necessary for analysis, is less important in the biotechnology sector which frequently uses large-scale produced bulk products for analysis. The recently developed high-throughput DSC and ITC microcalorimeters will additionally reduce the labour intensity of these techniques. Due to the precision of microcalorimetric analyses and the versatility of processes which can be studied, it is expected that ITC and DSC will soon be key technologies in biotechnological research.
Topics: Bacteria; Bacterial Proteins; Biotechnology; Calorimetry; Thermodynamics
PubMed: 21261830
DOI: 10.1111/j.1751-7915.2007.00013.x -
Scientific Reports Aug 2022The Wiseman fitting can be used to extract binding parameters from ITC data sets, such as heat of binding, number of binding sites, and the overall dissociation rate....
The Wiseman fitting can be used to extract binding parameters from ITC data sets, such as heat of binding, number of binding sites, and the overall dissociation rate. The classical Wiseman fitting assumes a direct binding process and neglects the possibility of intermediate binding steps. In principle, it only provides thermodynamic information and not the kinetics of the process. In this article we show that a concentration dependent dissociation constant could possibly stem from intermediate binding steps. The mathematical form of this dependency can be exploited with the aid of the Robust Perron Cluster Cluster Analysis method. Our proposed extension of the Wiseman fitting rationalizes the concentration dependency, and can probably also be used to determine the kinetic parameters of intermediate binding steps of a multivalent binding process. The novelty of this paper is to assume that the binding rate varies per titration step due to the change of the ligand concentration and to use this information in the Wiseman fitting. We do not claim to produce the most accurate values of the binding parameters, we rather present a novel method of how to approach multivalent bindings from a different angle.
Topics: Binding Sites; Calorimetry; Kinetics; Ligands; Protein Binding; Thermodynamics
PubMed: 35927455
DOI: 10.1038/s41598-022-17188-x -
Biomolecules Mar 2022Metals and metal-based compounds have many implications in biological systems. They are involved in cellular functions, employed in the formation of metal-based drugs... (Review)
Review
Metals and metal-based compounds have many implications in biological systems. They are involved in cellular functions, employed in the formation of metal-based drugs and present as pollutants in aqueous systems, with toxic effects for living organisms. Amphiphilic molecules also play important roles in the above bio-related fields as models of membranes, nanocarriers for drug delivery and bioremediating agents. Despite the interest in complex systems involving both metal species and surfactant aggregates, there is still insufficient knowledge regarding the quantitative aspects at the basis of their binding interactions, which are crucial for extensive comprehension of their behavior in solution. Only a few papers have reported quantitative analyses of the thermodynamic, kinetic, speciation and binding features of metal-based compounds and amphiphilic aggregates, and no literature review has yet addressed the quantitative study of these complexes. Here, we summarize and critically discuss the recent contributions to the quantitative investigation of the interactions of metal-based systems with assemblies made of amphiphilic molecules by calorimetric, spectrophotometric and computational techniques, emphasizing the unique picture and parameters that such an analytical approach may provide, to support a deep understanding and beneficial use of these systems for several applications.
Topics: Calorimetry; Coordination Complexes; Kinetics; Metals; Thermodynamics
PubMed: 35327600
DOI: 10.3390/biom12030408 -
Biophysical Journal Dec 2022High hydrostatic pressure can have profound effects on the stability of biomacromolecules. The magnitude and direction (stabilizing or destabilizing) of this effect is...
High hydrostatic pressure can have profound effects on the stability of biomacromolecules. The magnitude and direction (stabilizing or destabilizing) of this effect is defined by the volume changes in the system, ΔV. Positive volume changes will stabilize the starting native state, whereas negative volume changes will lead to the stabilization of the final unfolded state. For the DNA double helix, experimental data suggested that when the thermostability of dsDNA is below 50°C, increase in hydrostatic pressure will lead to destabilization; i.e., helix-to-coil transition has negative ΔV. In contrast, the dsDNA sequences with the thermostability above 50°C showed positive ΔV values and were stabilized by hydrostatic pressure. In order to get insight into this switch in the response of dsDNA to hydrostatic pressure as a function of temperature, first we further validated this trend using experimental measurements of ΔV for 10 different dsDNA sequences using pressure perturbation calorimetry. We also developed a computational protocol to calculate the expected volume changes of dsDNA unfolding, which was benchmarked against the experimental set of 50 ΔV values that included, in addition to our data, the values from the literature. Computation predicts well the experimental values of ΔV. Such agreement between computation and experiment lends credibility to the computation protocol and provides molecular level rational for the observed temperature dependence of ΔV that can be traced to the hydration. Difference in the ΔV value for A/T versus G/C basepairs is also discussed.
Topics: DNA; Hydrostatic Pressure; Temperature; Calorimetry; Thermodynamics
PubMed: 35962547
DOI: 10.1016/j.bpj.2022.08.005 -
Chemistry (Weinheim An Der Bergstrasse,... Feb 2022Quadruplex-duplex (Q-D) junctions are increasingly considered promising targets for medicinal and technological applications. Here, a Q-D hybrid with a hairpin-type...
Quadruplex-duplex (Q-D) junctions are increasingly considered promising targets for medicinal and technological applications. Here, a Q-D hybrid with a hairpin-type snapback loop coaxially stacked onto the quadruplex 3'-outer tetrad was designed and employed as a target structure for the indoloquinoline ligand SYUIQ-5. NMR spectral analysis demonstrated high-affinity binding of the ligand at the quadruplex-duplex interface with association constants determined by isothermal titration calorimetry of about 10 M and large exothermicities ΔH° of -14 kcal/mol in a 120 mM K buffer at 40 °C. Determination of the ligand-bound hybrid structure revealed intercalation of SYUIQ-5 between 3'-outer tetrad and the neighboring CG base pair, maximizing π-π stacking as well as electrostatic interactions with guanine carbonyl groups in close vicinity to the positively charged protonated quinoline nitrogen of the tetracyclic indoloquinoline. Exhibiting considerable flexibility, the SYUIQ-5 sidechain resides in the duplex minor groove. Based on comparative binding studies with the non-substituted N5-methylated indoloquinoline cryptolepine, the sidechain is suggested to confer additional affinity and to fix the alignment of the intercalated indoloquinoline aromatic core. However, selectivity for the Q-D junction mostly relies on the geometry and charge distribution of the indoloquinoline ring system. The presented results are expected to provide valuable guidelines for the design of ligands specifically targeting Q-D interfaces.
Topics: Calorimetry; G-Quadruplexes; Ligands; Molecular Structure; Thermodynamics
PubMed: 34905232
DOI: 10.1002/chem.202103718 -
Resting energy expenditure in critically ill patients: Evaluation methods and clinical applications.Revista Da Associacao Medica Brasileira... Oct 2016Patients on intensive care present systemic, metabolic, and hormonal alterations that may adversely affect their nutritional condition and lead to fast and important... (Review)
Review
Patients on intensive care present systemic, metabolic, and hormonal alterations that may adversely affect their nutritional condition and lead to fast and important depletion of lean mass and malnutrition. Several factors and medical conditions can influence the energy expenditure (EE) of critically ill patients, such as age, gender, surgery, serious infections, medications, ventilation modality, and organ dysfunction. Clinical conditions that can present with EE change include acute kidney injury, a complex disorder commonly seen in critically ill patients with manifestations that can range from minimum elevations in serum creatinine to renal failure requiring dialysis. The nutritional needs of this population are therefore complex, and determining the resting energy expenditure is essential to adjust the nutritional supply and to plan a proper diet, ensuring that energy requirements are met and avoiding complications associated with overfeeding and underfeeding. Several evaluation methods of EE in this population have been described, but all of them have limitations. Such methods include direct calorimetry, doubly labeled water, indirect calorimetry (IC), various predictive equations, and, more recently, the rule of thumb (kcal/kg of body weight). Currently, IC is considered the gold standard.
Topics: Acute Kidney Injury; Algorithms; Calorimetry; Critical Illness; Energy Metabolism; Female; Humans; Male; Nutritional Requirements; Predictive Value of Tests; Rest
PubMed: 27925048
DOI: 10.1590/1806-9282.62.07.672 -
Journal of Biomolecular Techniques : JBT Dec 2010This paper reviews the best-known differential scanning calorimetries (DSCs), such as conventional DSC, microelectromechanical systems-DSC, infrared-heated DSC,... (Review)
Review
This paper reviews the best-known differential scanning calorimetries (DSCs), such as conventional DSC, microelectromechanical systems-DSC, infrared-heated DSC, modulated-temperature DSC, gas flow-modulated DSC, parallel-nano DSC, pressure perturbation calorimetry, self-reference DSC, and high-performance DSC. Also, we describe here the most extensive applications of DSC in biology and nanoscience.
Topics: Calorimetry, Differential Scanning; Crystallization; Microscopy, Electron, Scanning; Nanostructures; Nanotechnology; Temperature; Thermodynamics
PubMed: 21119929
DOI: No ID Found -
Biochimica Et Biophysica Acta May 2016Isothermal titration calorimetry (ITC) is a general technique that allows for precise and highly sensitive measurements. These measurements may provide a complete and... (Review)
Review
BACKGROUND
Isothermal titration calorimetry (ITC) is a general technique that allows for precise and highly sensitive measurements. These measurements may provide a complete and accurate thermodynamic description of association processes in complex systems such as colloidal mixtures.
SCOPE OF THE REVIEW
This review will address uses of ITC for studies of surfactant aggregation to form micelles, with emphasis on the thermodynamic studies of homologous surfactant series. We will also review studies on surfactant association with polymers of different molecular characteristics and with colloidal particles.
GENERAL SIGNIFICANCE
ITC studies on the association of different homologous series of surfactants provide quantitative information on independent contribution from their apolar hydrocarbon chains and polar headgroups to the different thermodynamic functions associated with micellization (Gibbs energy, enthalpy and entropy). Studies on surfactant association to polymers by ITC provide a comprehensive description of the association process, including examples in which particular features revealed by ITC were elucidated by using ancillary techniques such as light or X-ray scattering measurements. Examples of uses of ITC to follow surfactant association to biomolecules such as proteins or DNA, or nanoparticles are also highlighted. Finally, recent theoretical models that were proposed to analyze ITC data in terms of binding/association processes are discussed.
MAJOR CONCLUSIONS
This review stresses the importance of using direct calorimetric measurements to obtain and report accurate thermodynamic data, even in complex systems. These data, whenever possible, should be confirmed and associated with other ancillary techniques that allow elucidation of the nature of the transformations detected by calorimetric results, providing a complete description of the process under scrutiny.
Topics: Calorimetry; Colloids; DNA; Hydrophobic and Hydrophilic Interactions; Micelles; Nanoparticles; Proteins; Static Electricity; Surface-Active Agents; Temperature; Thermodynamics
PubMed: 26459003
DOI: 10.1016/j.bbagen.2015.10.003 -
Acta Crystallographica. Section F,... Dec 2022An important interface between biophysical chemistry and biological crystal structures involves whether it is possible to relate experimental calorimetry measurements of...
An important interface between biophysical chemistry and biological crystal structures involves whether it is possible to relate experimental calorimetry measurements of protein ligand binding to 3D structures. This has proved to be challenging. The probes of the structure of matter, namely X-rays, neutrons and electrons, have challenges of one type or another in their use. This article focuses on saccharide binding to lectins as a theme, yet after 25 years or so it is still a work in progress to connect 3D structure to binding energies. Whilst this study involved one type of protein (lectins) and one class of ligand (monosaccharides), i.e. it was specific, it was of general importance, as measured for instance by its wide impact. The impetus for writing this update now, as a Scientific Comment, is that a breakthrough in neutron crystal structure determinations of saccharide-bound lectins has been achieved. It is suggested here that this new research from neutron protein crystallography could improve, i.e. reduce, the errors in the estimated binding energies.
Topics: Ligands; Crystallography, X-Ray; Thermodynamics; Lectins; Calorimetry
PubMed: 36458619
DOI: 10.1107/S2053230X22011244 -
Biophysical Journal Sep 2021Time-resolved fluorescence and differential scanning calorimetry (DSC) were used to examine how two amino acids, L-phenylalanine (L-PA) and N-acetyl-DL-tryptophan (NAT),...
Time-resolved fluorescence and differential scanning calorimetry (DSC) were used to examine how two amino acids, L-phenylalanine (L-PA) and N-acetyl-DL-tryptophan (NAT), affect the temperature-dependent membrane affinity of two structurally similar coumarin solutes for 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) vesicles. The 7-aminocoumarin solutes, coumarin 151 (C151) and coumarin 152 (C152), differ in their substitution at amine position-C151 is a primary amine, and C152 is a tertiary amine-and both solutes show different tendencies to associate with lipid bilayers consistent with differences in their respective log-P-values. Adding L-PA to the DPPC vesicle solution did not change C151's propensity to remain freely solvated in aqueous solution, but C152 showed a greater tendency to partition into the hydrophobic bilayer interior at temperatures below DPPC's gel-liquid crystalline transition temperature (T). This finding is consistent with L-PA's ability to enhance membrane permeability by disrupting chain-chain interactions. Adding NAT to DPPC-vesicle-containing solutions changed C151 and C152 affinity for the DPPC membranes in unexpected ways. DSC data show that NAT interacts strongly with the lipid bilayer, lowering T by up to 2°C at concentrations of 10 mM. These effects disappear when either C151 or C152 is added to solution at concentrations below 10 μM, and T returns to a value consistent with unperturbed DPPC bilayers. Together with DSC results, fluorescence data imply that NAT promotes coumarin adsorption to the vesicle bilayer surface. NAT's effects diminish above T and imply that unlike L-PA, NAT does not penetrate into the bilayer but instead remains adsorbed to the bilayer's exterior. Taken in their entirety, these discoveries suggest that amino acids-and by inference, polypeptides and proteins-change solute affinity for lipid bilayers with specific effects that depend on individualized amino-acid-lipid-bilayer interactions.
Topics: 1,2-Dipalmitoylphosphatidylcholine; Amines; Amino Acids; Calorimetry, Differential Scanning; Lipid Bilayers; Solutions
PubMed: 34310940
DOI: 10.1016/j.bpj.2021.07.021