Survey of the year 2005: literature on applications of isothermal titration calorimetry

Ababou, Adessamad; Ladbury, John E.

doi:10.1002/jmr.803

Cited by 70 publications

(50 citation statements)

References 205 publications

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“…However, back-scattering interferometry (BSI) is a free-solution label-free technique with the added benefit of sensitivity that rivals fluorescence (9). There are other techniques performed in free solution, such as MS (10,11) and NMR (12,13) and the widely used isothermal titration calorimetry (ITC) (14,15). As with NMR, ITC has many advantages, but exhibits modest sensitivity and often requires large sample quantities.…”

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confidence: 99%

Origin and prediction of free-solution interaction studies performed label-free

Bornhop

Kammer

Kussrow

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Interaction/reaction assays have led to significant scientific discoveries in the biochemical, medical, and chemical disciplines. Several fundamental driving forces form the basis of intermolecular and intramolecular interactions in chemical and biochemical systems (London dispersion, hydrogen bonding, hydrophobic, and electrostatic), and in the past three decades the sophistication and power of techniques to interrogate these processes has developed at an unprecedented rate. In particular, label-free methods have flourished, such as NMR, mass spectrometry (MS), surface plasmon resonance (SPR), biolayer interferometry (BLI), and backscattering interferometry (BSI), which can facilitate assays without altering the participating components. The shortcoming of most refractive index (RI)-based label-free methods such as BLI and SPR is the requirement to tether one of the interaction entities to a sensor surface. This is not the case for BSI. Here, our hypothesis is that the signal origin for freesolution, label-free determinations can be attributed to conformation and hydration-induced changes in the solution RI. We propose a model for the free-solution response function (FreeSRF) and show that, when quality bound and unbound structural data are available, FreeSRF correlates well with the experiment (R 2 > 0.99, Spearman rank correlation coefficients >0.9) and the model is predictive within ∼15% of the experimental binding signal. It is also demonstrated that a simple mass-weighted dη/dC response function is the incorrect equation to determine that the change in RI is produced by binding or folding event in free solution.backscattering interferometry | assay methodology | molecular interactions | conformation change | hydration change C ontemporary assays enabling single-molecule detection (1,2) have accelerated the sequencing of the human genome (3) and facilitated imaging with extraordinary resolution without labels (4). To most closely approximate the natural state, an interaction assay methodology would interrogate the processes (reaction, molecular interaction, protein folding event, etc.) without perturbation. Label-free chemical and biochemical investigations (5, 6) transduce the desired signal without an exogenous label (fluorescent, radioactive, or otherwise) representing an essential step toward this goal. Many label-free methods require one of the interacting species to be either tethered or immobilized to the sensor surface, introducing a potential perturbation to the natural state of the species (7,8). However, back-scattering interferometry (BSI) is a free-solution label-free technique with the added benefit of sensitivity that rivals fluorescence (9). There are other techniques performed in free solution, such as MS (10, 11) and NMR (12,13) and the widely used isothermal titration calorimetry (ITC) (14, 15). As with NMR, ITC has many advantages, but exhibits modest sensitivity and often requires large sample quantities. Another increasingly popular free-solution approach is microscale thermophoresis (...

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confidence: 99%

Origin and prediction of free-solution interaction studies performed label-free

Bornhop

Kammer

Kussrow

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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“…For measurements at very low concentrations, detection of molecules often requires labeling (such as fluorescent tags), but label-free studies can be performed in two main ways. Calorimetric methods, such as isothermal titration calorimetry (ITC) (1)(2)(3), are performed with all components in solution and have found relatively widespread acceptance. However, these methods have very low throughput, require large sample volumes (milliliters), and have low sensitivity (Table 1) (in the worst case, there is no sensitivity if the reaction enthalpy is near zero).…”

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confidence: 99%

Free-Solution, Label-Free Molecular Interactions Studied by Back-Scattering Interferometry

Bornhop

Latham

Kussrow

et al. 2007

Science

190

216

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Free-solution, label-free molecular interactions were investigated with back-scattering interferometry in a simple optical train composed of a helium-neon laser, a microfluidic channel, and a position sensor. Molecular binding interactions between proteins, ions and protein, and small molecules and protein, were determined with high dynamic range dissociation constants (K d spanning six decades) and unmatched sensitivity (picomolar K d 's and detection limits of 10,000s of molecules). With this technique, equilibrium dissociation constants were quantified for protein A and immunoglobulin G, interleukin-2 with its monoclonal antibody, and calmodulin with calcium ion Ca 2+ , a small molecule inhibitor, the protein calcineurin, and the M13 peptide. The high sensitivity of back-scattering interferometry and small volumes of microfluidics allowed the entire calmodulin assay to be performed with 200 picomoles of solute.

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“…The principle is compellingly simple. Molecule M 1 is added in small aliquots to the calorimetric cell, which contains the binding partner, M 2 changes in hydration, changes in the number of ions bound to the free components and the complex, proton uptake/release, conformational transitions, etc, all of which are manifested by heat changes. The raw data have to be corrected for "unspecific heats" by performing blank titrations of ligand into buffer and buffer into the macromolecule.…”

Section: Introductionmentioning

confidence: 99%