Efficient Through-Bond Propagation of Nuclear-Spin Hyperpolarization via TOCSY-Enhanced LC-Photo-CIDNP

Nuclear magnetic resonance (NMR) is a powerful tool for studying biomolecules in their natural state. However, NMR has a low sensitivity that becomes a major issue when analyzing low-concentration samples. Low-concentration photochemically induced dynamic nuclear polarization (LC-photo-CIDNP) is an approach that uses light to greatly enhance NMR sensitivity in a physiological environment.

Unfortunately, LC-photo-CIDNP only works well with certain types of nuclei, limiting the amount of detailed information that can be gathered.

Researchers have found a way to overcome this limitation by combining LC-photo-CIDNP with a technique called Total Correlation Spectroscopy (TOCSY). TOCSY allows the initial hyperpolarization from LC-photo-CIDNP to be transferred to other nuclei through a series of connected spins. The team first showed that this method can efficiently transfer the LC-photo-CIDNP signal throughout an entire molecule using 1D experiments and detecting hydrogen or carbon-13.

Next, they applied the technique to a model protein and demonstrated successful polarization transfer using both 1D and 2D 1H-detected 13C-TOCSY LC-photo-CIDNP experiments. This means that even nuclei that are not naturally photo-CIDNP active can be visualized using 13C-1H correlations in just a few minutes, down to concentrations as low as 10 millimolar.

This new method opens up the possibility of obtaining detailed structural information about amino acids and proteins at unprecedented low concentrations.