An ISA-Tab specification for protein titration data exchange

Data curation presents a challenge to all scientific disciplines to ensure public availability and reproducibility of experimental data. Standards for data preservation and exchange are central to addressing this challenge: the Investigation-Study-Assay Tabular (ISA-Tab) project has developed a widely used template for such standards in biological research. This paper describes the application of ISA-Tab to protein titration data. Despite the importance of titration experiments for understanding protein structure, stability, and function and for testing computational approaches to protein electrostatics, no such mechanism currently exists for sharing and preserving biomolecular titration data. We have adapted the ISA-Tab template to provide a structured means of supporting experimental structural chemistry data with a particular emphasis on the calculation and measurement of pKa values. This activity has been performed as part of the broader pKa Cooperative effort, leveraging data that has been collected and curated by the Cooperative members. In this article, we present the details of this specification and its application to a broad range of pKa and electrostatics data obtained for multiple protein systems. The resulting curated data is publicly available at http://pkacoop.org.