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Modeling of the Response of Hydrogen Bond Properties on an External Electric Field: Geometry, NMR Chemical Shift, Spin-Spin Scalar Coupling.

ABSTRACT: The response of the geometric and NMR properties of molecular systems to an external electric field has been studied theoretically in a wide field range. It has been shown that this adduct under field approach can be used to model the geometric and spectral changes experienced by molecular systems in polar media if the system in question has one and only one bond, the polarizability of which significantly exceeds the polarizability of other bonds. If this requirement is met, then it becomes possible to model even extreme cases, for example, proton dissociation in hydrogen halides. This requirement is fulfilled for many complexes with one hydrogen bond. For such complexes, this approach can be used to facilitate a detailed analysis of spectral changes associated with geometric changes in the hydrogen bond. For example, in hydrogen-bonded complexes of isocyanide C≡¹⁵N-¹H⋯X, ¹J(¹⁵N¹H) depends exclusively on the N-H distance, while δ(¹⁵N) is also slightly influenced by the nature of X.

SUBMITTER: Shenderovich IG

PROVIDER: S-EPMC8399935 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Residence Times of Molecular Complexes in Solution from NMR Data of Intermolecular Hydrogen-Bond Scalar Coupling.

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| S-EPMC4850060 | biostudies-literature

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| S-EPMC5657093 | biostudies-literature

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| S-EPMC6289736 | biostudies-literature

Model of B9N9 Response under External Electric Field: Geometry, Electronic Properties, Reaction Activity.

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Nuclear spin coupling crossover in dense molecular hydrogen.

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Project description:Despite their importance for biological activity, slower molecular motions beyond the nanosecond range remain poorly understood. We have assembled an unprecedented set of experimental NMR data, comprising up to 27 residual dipolar couplings per amino acid, to define the nature and amplitude of backbone motion in protein G using the Gaussian axial fluctuation model in three dimensions. Slower motions occur in the loops, and in the beta-sheet, and are absent in other regions of the molecule, including the alpha-helix. In the beta-sheet an alternating pattern of dynamics along the peptide sequence is found to form a long-range network of slow motion in the form of a standing wave extending across the beta-sheet, resulting in maximal conformational sampling at the interaction site. The alternating nodes along the sequence match the alternation of strongly hydrophobic side chains buried in the protein core. Confirmation of the motion is provided through extensive cross-validation and by independent hydrogen-bond scalar coupling analysis that shows this motion to be correlated. These observations strongly suggest that dynamical information can be transmitted across hydrogen bonds and have important implications for understanding collective motions and long-range information transfer in proteins.

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