FIT

data analysis
Traitement de données complexes

Analyse d'interactions complexes grâce au logiciel permettant la création de modèles originaux pour le traitement de données ITC et DSC. 

FIT is the complex of advanced web tools for ITC data analysis and management. Its development is financed by European FP7 (Marie Curie Actions, Project No: 627524). ITC is a major widespread experimental method for studying biomolecular interaction. It allows a direct measurement of heat of reaction resulting in determination of enthalpy change. Nevertheless, to take full advantage of such powerful technique and obtain all thermodynamic parameters of interaction, experimental ITC data needs be analyzed with the help of software using the appropriate binding model. Currently all ITC devices are equipped by manufactures with tools for data analysis. Unfortunately the set of binding models that can be used for data analysis in standard software is very narrow and limited to several basic models, such as:

  1. model of several equal binding sites,
  2. model of two sets of equal binding sites and
  3. sequential binding model.

This set of models allows routine analysis of a large class of intermolecular interactions. Nevertheless, there are many molecular mechanisms which cannot be properly analyzed using these basic models. Thus, in the case of

  1. three or more different binding sites,
  2. one site with multiple binding mechanisms,
  3. binding accompanied by polymerization of one of the interactant,
  4. three or more components binding,

new models need to be developed and implemented on a case-by-case basis by ITC end users. The absence of appropriate ITC fitting software slows down significantly such studies, since it requires the involvement of researchers able to create the mathematical model of interaction and implement it using programming language. Such data analysis tools realized by ITC end users usually implement only one model (of interest to authors), use different programming languages, platforms, formats and have different (not always user-friendly) interfaces. That is why, in most cases such implementations are rarely used by other researchers. Attempts to provide these tools for a wider use often result in the creation of crude software product with poor interface, which frequently use expensive numerical computing environment (MATLAB, Mathematica etc.) and do not really extend the list of the fitting models. Unfortunately, specialized fitting software designed for a wide range of applications is also not easy to use to analyze ITC data. In most cases it requires that theoretical ITC curve be explicitly described by function of one variable. This is not possible in cases of ITC data since in the most cases the system of equations, which describing ITC curves, cannot be solved analytically. Thus, available software does not provide easy way to create binding models and requires strong mathematical background.

ITC end users often face another problem, which complicates their investigation: the poor organization of ITC data output. In fact, standard software does not organize ITC data at all, contrarily to software for other widely used methods with high output such as chromatography and mass-spectrometry. This problem is not as crucial as lack of fitting models, but still bothersome and more common. The simple task to find and print all ITC data obtained for precise ligand at specific pH can become a nightmare. Often, even in small labs, several operators collect data from several ITC instruments (sometimes from different manufacturers) and work simultaneously on several research projects. In large collaborative projects, ITC experiments can be carried out in different places and generates hundreds files which have to be analyzed. Being stored in file system, ITC data become hardly manageable and unsearchable by experimental parameters. Thus, the absence of data management tool, which is able to search, integrate and harmonize experimental data, could significantly complicate projects management and data analysis.

FIT significantly facilitate the investigation of complex molecular mechanisms of interaction by ITC and is useful for any ITC end users. At this moment FIT available only for internal use. Nevertheless, it will be shared with all end users shortly.