Time‐Resolved Chemically Induced Dynamic Nuclear Polarization of Biologically Important Molecules

Abstract

In this work, we review the hyperpolarization technique named chemically induced dynamic nuclear polarization (CIDNP), focusing on the time‐resolved variant of this method and its biological applications. We introduce the main principles of polarization formation in liquids at high magnetic fields, provided by the so‐called spin sorting mechanism. Applications of CIDNP to studying fast reactions of short‐lived free radicals of biologically important molecules are discussed, as well as the potential of the method to probe the structure and magnetic parameters of such radicals. We also explain the principles of protein CIDNP and discuss applications of time‐resolved CIDNP to studies of protein structure and dynamics.

Photochemically Induced Dynamic Nuclear Polarization of Heteronuclear Singlet Order

“…2 Apart from hyperpolarizing the spins, CIDNP also enables studying short-lived radicals, 3 obtaining information about their magnetic properties, 4 and exploring mechanisms of chemical reactions. 5 Photo-CIDNP is also a suitable method to polarize biologically relevant molecules, 6 including amino acids, 7 polypeptides and proteins, 8 and nucleotides, 9 and to study their reactivity.…”

Real-time NMR spectroscopy in the study of biomolecular kinetics and dynamics

“…Embedded in a protein or peptide, Trp, Tyr, His and Met show signal enhancement if they are accessible to a photosensitizer (Kaptein et al, 1978;Hore and Broadhurst, 1993). For the photo-CIDNP reaction different dyes as photosensitizer can be used, the most common ones are substituted flavins, 2,2-dipyridyl (DP), 4-carboxybenzophenone (4-CBP), and 3,3',4,4'-tetracarboxybenzophenone (TCBP) (Morozova and Ivanov, 2019).…”

“…During protein folding and refolding, the solvent accessible area of a protein is changing due to hydrophobic collapse that rearranges the conformation of solvent exposed amino acids. This probing of differential accessibility makes photo-CIDNP a powerful tool for the (real-time) investigation of protein folding (Hore and Broadhurst, 1993;Kuhn, 2013;Morozova and Ivanov, 2019).…”

Real-time nuclear magnetic resonance spectroscopy in the study of biomolecular kinetics and dynamics

“…Alternating light (with laser irradiation) and dark (without irradiation) spectra are recorded and subtracted to obtain the difference spectra with the enhanced signals (Hore and Broadhurst, 1993). Several amino acids exhibit polarisation by photo-CIDNP in solu-tion: these are tryptophan, tyrosine, histidine and also methionine, glycine and methylcysteine, although to different extents (Stob and Kaptein, 1989;Morozova et al, 2005;Morozova and Yurkovskaya, 2008;Morozova et al, 2016). Embedded in a protein or peptide, Trp, Tyr, His and Met show signal enhancement if they are accessible to a photosensitiser (Kaptein et al, 1978;Hore and Broadhurst, 1993).…”