Binding Isotherms and Time Courses Readily from Magnetic Resonance

Area of Science:

• Analytical Chemistry
• Biophysics
• Spectroscopy

Background:

• Traditional analysis of Nuclear Magnetic Resonance (NMR) spectra for binding studies often requires complex peak picking and interpretation.
• Intermediate and mixed exchange regimes in NMR titrations can distort conventional binding isotherm analysis.

Purpose of the Study:

• To present a novel method for directly extracting binding isotherms from complex 2D NMR spectra using Principal Component Analysis (PCA).
• To demonstrate the utility of PCA in analyzing binding events across various exchange regimes and data types, including time-domain NMR and magnetic resonance imaging (MRI).

Main Methods:

• Direct application of Principal Component Analysis (PCA) to non-interpreted, complex 2D NMR spectra.
• Utilizing Pareto scaling to overcome spectral distortions in intermediate exchange regimes.
• Applying PCA to time-domain NMR data and magnetic resonance imaging (MRI) movie time courses.

Main Results:

• PCA successfully extracts binding isotherms (simple or biphasic) directly from 2D NMR spectra, obviating the need for peak picking.
• The first principal component captures binding isotherms in fast, slow, intermediate, and mixed exchange regimes for protein-ligand associations.
• PCA accurately delineates two-step binding processes and extracts dynamic information like breathing and heart rate from MRI data.

Conclusions:

• PCA provides a robust and direct method for determining binding isotherms and reaction kinetics from complex NMR data.
• This approach simplifies the analysis of NMR-detected titrations and extends to dynamic processes observed in MRI.
• PCA offers a powerful alternative to traditional spectral analysis, enhancing the study of molecular interactions and dynamic biological processes.