pyTRACTnmr: an open source python package for analyzing [¹⁵N, ¹H]-TRACT experiments

The rotational correlation time ([Formula: see text]) is a one of the fundamental parameters for characterizing biomacromolecules in solution. The [¹⁵N, ¹H]-TRACT (TROSY for Rotational Correlation Times) NMR experiment is a widely utilized method for determining [Formula: see text] by measuring the differential ¹⁵N-¹H transverse relaxation rates of α and β states. However, extracting accurate relaxation rates from these experiments often requires researchers to rely on ad hoc scripts or tedious workflows across multiple software packages, which can introduce systematic errors during peak integration and baseline correction. To address this bottleneck, we introduce pyTRACTnmr, an open-source, modular Python application featuring a modern graphical user interface designed specifically for streamlined analysis of [¹⁵N, ¹H]-TRACT data. Built on the PySide6 framework and leveraging the nmrglue library for robust data ingestion, the software provides an interactive environment for visual baseline correction, precise integration window definition, and non-linear least-squares fitting of relaxation decays. By replacing rigid automated processing with a user-friendly, visually guided workflow, pyTRACTnmr minimizes noise amplification and ensures highly reproducible analysis, and significantly simplifies the workflow.