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Updated: Jun 10, 2026

Atomic Scale Structural Studies of Macromolecular Assemblies by Solid-state Nuclear Magnetic Resonance Spectroscopy
Published on: September 17, 2017
A solid-state (17)O NMR study of L-tyrosine in different ionization states: implications for probing tyrosine side
Jianfeng Zhu1, Justin Y C Lau, Gang Wu
1Department of Chemistry, Queen's University, 90 Bader Lane, Kingston, Ontario, Canada K7L 3N6.
Abstract:
We report experimental characterization of (17)O quadrupole coupling (QC) and chemical shift (CS) tensors for the phenolic oxygen in three l-tyrosine (l-Tyr) compounds: l-Tyr, l-Tyr.HCl, and Na(2)(l-Tyr). This is the first time that these fundamental (17)O NMR tensors are completely determined for phenolic oxygens in different ionization states. We find that, while the (17)O QC tensor changes very little upon phenol ionization, the (17)O CS tensor displays a remarkable sensitivity. In particular, the isotropic (17)O chemical shift increases by approximately 60 ppm upon phenol ionization, which is 6 times larger than the corresponding change in the isotropic (13)C chemical shift for the C(zeta) nucleus of the same phenol group. By examining the CS tensor orientation in the molecular frame of reference, we discover a "cross-over" effect between delta(11) and delta(22) components for both (17)O and (13)C CS tensors. We demonstrate that the knowledge of such "cross-over" effects is crucial for understanding the relationship between the observed CS tensor components and chemical bonding. Our results suggest that solid-state (17)O NMR can potentially be used to probe the ionization state of tyrosine side chains in proteins.
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