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Updated: May 21, 2025

Dissolution Dynamic Nuclear Polarization Instrumentation for Real-time Enzymatic Reaction Rate Measurements by NMR

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Published on: February 23, 2016

In Situ Light-driven pH Modulation for NMR Studies.

Aarav Barde¹, Ruixian Han², Martin A Olson¹

¹Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA.

Angewandte Chemie (International Ed. in English)

|March 22, 2025

Summary

This summary is machine-generated.

Researchers developed a new method for controlling pH in Nuclear Magnetic Resonance (NMR) samples using light-activated photoacids. This technique allows precise, noninvasive pH adjustments within the NMR magnet, reducing sample handling and improving experimental reliability.

Keywords:

Buffer NMR Photo illumination Photoacid Protonation Titration

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Area of Science:

Chemistry
Biophysics
Analytical Chemistry

Background:

Proton exchange is crucial in chemical and biological systems.
Nuclear Magnetic Resonance (NMR) spectroscopy offers site-specific resolution for studying protonation events.
Traditional pH titration for NMR requires extensive sample handling and can lead to sample loss.

Purpose of the Study:

To introduce a novel, noninvasive method for controlling pH in NMR samples.
To demonstrate precise, in situ pH modulation using light-activated photoacids.
To reduce sample handling and improve the reliability of pH-dependent NMR studies.

Main Methods:

Utilized water-soluble photoacids to alter solution pH upon photoillumination.
Controlled pH by adjusting illumination wavelength and intensity.
Monitored in situ pH using internal standards with pH-sensitive chemical shifts.
Applied the method to protein samples with significant buffering capacity (>100 µM).

Main Results:

Achieved precise and calibrated pH control within the NMR magnet.
Demonstrated successful pH alteration from near neutral to acidic conditions.
Showcased the release of sufficient protons to induce meaningful pH changes in buffered samples.
Significantly reduced the need for extensive sample manipulation.

Conclusions:

Light-induced pH control offers a robust and reliable alternative for NMR experiments.
This novel approach enhances the efficiency and accuracy of pH-dependent NMR studies.
The method has broad applicability for investigating protonation events in various biological and chemical samples.