AFFINImeter is a web-based application developed to optimize the design of Isothermal Titration Calorimetry (ITC) experiments, to analyze ITC measurements, to aid in the interpretation of ITC data, and to organize and share ITC results.

AFFINImeter kinetics

KinITC is a new method to obtain kinetic information from Isothermal Titration Calorimetry Data. With one single titration experiment it calculates the kinetic constants (kon and koff) and the thermodynamic data (KD and ΔH) of 1:1 binding interactions.

Design your own model

Complex reaction schemes can be written to describe a real scenario in chemical language. The calculation of the thermodynamic parameters involved in those reactions requires the development of coupled equations associated to the different equilibria and the implementation of such equations in a computational code. AFFINImeter provides an exclusive “Model Builder” to write the chemical equations describing your system.
Using AFFINImeter you can simulate and/or analyze ITC data
  • Competitive Sequential Binding Models involving up to 3 different molecules without limitation in the stoichiometry of the resulting complexes.
  • Competitive Independent Binding Models without limitation in the number of sets of identical sites.

Perform global analysis of several ITC isotherms

Complex binding models are usually described by many variable parameters and, in such cases, a single experimental curve is insufficient to achieve a robust analysis. Instead, the simultaneous analysis of several curves must be performed. If the same model applies to all the measurements, the parameters of the different curves should be identical to each other. There are also situations where a different model applies to each experimental curve but one or more parameters are shared. This happens, for instance, when combining an experiment involving two competing ligands and a host with another experiment where one of the ligands is absent. Additionally, mainly when applying complex models, you may want to correlate parameters by means of analytical or logical equations. All the situations described in this paragraph can be easily solved using AFFINImeter.

Check the local minima

To be certain that the fit results found by AFFINImeter is the global minimum of the objective function, the refinement starts with widely differing initial values of the parameters. When the same minimum is found regardless of the starting point, it is likely to be the global minimum. AFFINImeter provides all the information needed to analyze and edit the fitting procedure. Besides the best fitting solution, it makes available the results obtained with, at least, ten independent “seeds”, and also allows you to quickly search for local minima within a specific predefined range of values for each parameter.

Simulate ITC isotherms

The simulation tool allows designing ITC experiments in order to optimize the experimental settings: compound concentrations, injection volume and number of titrations; thus avoiding trial and error tests and saving time, reactants and money. By using our simulation tool you will also be able to test different binding models and to predict the behavior of your system, including the distribution of chemical species at different concentrations of the involved compounds. The AFFINImeter simulation tool is freely available under registration.

Get advantage of working in the cloud

The fitting of complex isotherms requires the screening of the multidimensional geometrical space generated by all the variables. AFFINImeter is more than a web-based application that translates thermodynamic models from chemical equations to numerical results but also provides the computational resources required to perform your calculations. AFFINImeter is a “Software as a Service”; users have no hardware or software to install, maintain, or update. It can be accessed from different platforms and from different operating systems, you just need an Internet connection.

Get a detailed report of your experiment and analysis

The analysis of an ITC experiment can be squeezed to provide more than just thermodynamic parameters. AFFINImeter provides you with a complete high quality report that includes the thermal fingerprint of your system, species distribution representation as a function of the titrant to titrate molar ratio, three-dimensional plots showing a projection of the standard error versus fitting parameters hypersurface screened during the minimization process, summary tables including the resulting parameters with their uncertainties, the analysis of local minima and self-explanatory texts. This information can be directly shared with your colleagues and/or exported to be included in scientific publications.

On Development

AFFINImeter-Spectroscopy has been designed to analyze binding isotherms from steady-state measurements from different spectroscopic techniques such as NMR, SPR, IR, UV-vis or Fluorescence.
It allows curve fitting to complex binding models and global analysis of many isotherms obtained with different techniques.

AFFINImeter-Micellization allows a full thermodynamic characterization of micellization or demicellization processes measured by Isothermal Titration calorimetry, including the calculation of the micellization number, ΔG of micellization, critical micellization concentration and the dilution heats of the monomers and micelles.