Isothermal titration calorimetry (ITC) is a widely used method to determine binding affinities and thermodynamics in ligand–receptor interactions, but it also has the capability of providing detailed information on much more complex events. However, the lack of available methods to analyze ITC data is limiting the use of the technique in such multifaceted cases. Here, we present the software ANISPROU. Through a semi-empirical approach that allows for extraction of quantitative information from complex ITC data, ANISPROU solves an inverse problem where three parameters describing a set of predefined functions must be found. In analogy to strategies adopted in other scientific fields, such as geophysics, imaging, and many others, it employs an optimization algorithm which minimizes the difference between calculated and experimental data. In contrast to the existing methods, ANISPROU provides automated and objective analysis of ITC data on sodium dodecyl sulfate (SDS)-induced protein unfolding, and in addition, more information can be extracted from the data. Here, data series on SDS-mediated protein unfolding is analyzed, and binding isotherms and thermodynamic information on the unfolding events are extracted. The obtained binding isotherms as well as the enthalpy of different events are similar to those obtained using the existing manual methods, but our methodology ensures a more robust result, as the entire data set is used instead of single data points. We foresee that ANISPROU will be useful in other cases with complex enthalpograms, for example, in cases with coupled interactions in biomolecular, polymeric, and amphiphilic systems including cases where both structural changes and interactions occur simultaneously.

中文翻译：

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来自蛋白质-表面活性剂相互作用的复杂 ITC 数据的半经验分析

等温滴定量热法 (ITC) 是一种广泛使用的方法，用于确定配体 - 受体相互作用中的结合亲和力和热力学，但它也能够提供关于更复杂事件的详细信息。然而，缺乏分析 ITC 数据的可用方法限制了该技术在此类多方面案例中的使用。在这里，我们介绍软件 ANISPROU。通过允许从复杂的 ITC 数据中提取定量信息的半经验方法，ANISPROU 解决了必须找到描述一组预定义函数的三个参数的逆问题。与地球物理学、成像等其他科学领域采用的策略类似，它采用了一种优化算法，可最大限度地减少计算数据和实验数据之间的差异。与现有方法相比，ANISPROU 提供了对十二烷基硫酸钠 (SDS) 诱导的蛋白质解折叠的 ITC 数据的自动化和客观分析，此外，可以从数据中提取更多信息。在这里，分析了 SDS 介导的蛋白质解折叠的数据系列，并提取了解折叠事件的结合等温线和热力学信息。获得的结合等温线以及不同事件的焓与使用现有手动方法获得的相似，但我们的方法确保了更可靠的结果，因为使用整个数据集而不是单个数据点。我们预见 ANISPROU 将在其他具有复杂焓图的情况下有用，例如，在生物分子、聚合物、