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bioRxiv · 10.1101/512780

Rigorous equations for isothermal titration calorimetry: theoretical and practical consequences

Dumas, P.
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Abstract

The author has withdrawn his manuscript because: The withdrawn preprint was about methodological aspects in Isothermal Titration Calorimetry (ITC) used to obtain thermodynamic information about reactions like A + B {rightleftarrows} C where A is initially in the cell and B injected from a syringe. The preprint considered the two possible methods in ITC: 1/ the Multiple Injection Method (MIM) making use of short-time injections separated by sufficient time to allow the reaction to reach equilibrium before a new injection. 2/ the Single Injection Method (SIM) making use of a slow continuous injection. The first result mentioned is about a new equation linking the rate of heat evolution with the injected volume (equations 9 and 10). With this equation and with the hypothesis that there is always perfect mixing of the cell content it was concluded that an ideal titration curve (i.e. not affected by any external influence) for a simple reaction like A + B {rightleftarrows} C cannot change sign (section 3.2). This conclusion turns out to be incorrect when taking in consideration real conditions with imperfect mixing, particularly with MIM using injections often of very short duration, which prevents from reaching perfect mixing. The major problem is that this erroneous conclusion was accompanied with comparisons of the results from well-established programs, which led to the conclusion that these were in error on this point (section 3.6). I therefore felt necessary to withdraw this preprint to avoid casting doubts unduly on these programs used extensively. Note that many other aspects in this preprint remain correct (section 3.8). A new version of this work, limited to SIM and considering imperfect mixing, will be submitted for publication under the title: "Isothermal titration calorimetry in the single-injection mode with imperfect mixing". If you have any questions, please contact me at dumasp@igbmc.fr or at p.dumas@unistra.fr Sorry for the inconvenience. Philippe Dumas November 6, 2021

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Dumas, P.. 2019-01-06. Rigorous equations for isothermal titration calorimetry: theoretical and practical consequences. https://doi.org/10.1101/512780

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