Precision Measurements
of Deuterium Isotope Effects
on the Chemical Shifts of Backbone Nuclei in Proteins: Correlations
with Secondary Structure
- Publication date
- Publisher
Abstract
Precision NMR measurements of deuterium isotope effects
on the
chemical shifts of backbone nuclei in proteins (<sup>15</sup>N, <sup>13</sup>CO, <sup>13</sup>C<sub>α</sub>, and <sup>1</sup>HN)
arising from <sup>1</sup>H-to-<sup>2</sup>H substitutions at aliphatic
carbon sites. Isolation of molecular species with a defined protonation/deuteration
pattern at carbon-α/β positions allows distinguishing
and accurately quantifying different isotope effects within the protein
backbone. The isotope shifts measured in the partially deuterated
protein ubiquitin are interpreted in terms of backbone geometry via
empirical relationships describing the dependence of isotope shifts
on (φ; ψ) backbone dihedral angles. Because of their relatively
large magnitude and clear dependence on the protein secondary structure,
the two- and three-bond backbone amide <sup>15</sup>N isotope shifts, <sup>2</sup>ΔN(C<sub>α,i</sub>D) and <sup>3</sup>ΔN(C<sub>α,i‑1</sub>D), can find utility for NMR structural refinement
of small-to-medium size proteins