nounIntermediate
Definition
Spin–spin coupling between nearby atomic nuclei (typically ¹H or ¹³C) observed in nuclear magnetic resonance (NMR) spectroscopy.

Detailed Explanation

Spin–spin coupling between nearby atomic nuclei (typically ¹H or ¹³C) observed in nuclear magnetic resonance (NMR) spectroscopy. J-coupling constants (measured in Hz) provide information about peptide backbone dihedral angles, side chain conformations, and hydrogen bonding patterns. The ³J(HN-Hα) coupling constant is particularly useful: values of 3–6 Hz indicate α-helical structure, while 8–10 Hz indicate β-sheet conformation. NMR remains the primary method for determining the 3D structure of peptides in solution.

Key Facts

  • Spin–spin coupling between nearby atomic nuclei (typically ¹H or ¹³C) observed in nuclear magnetic resonance (NMR) spectroscopy.
  • J-coupling constants (measured in Hz) provide information about peptide backbone dihedral angles, side chain conformations, and hydrogen bonding patterns.
  • The ³J(HN-Hα) coupling constant is particularly useful: values of 3–6 Hz indicate α-helical structure, while 8–10 Hz indicate β-sheet conformation.
  • NMR remains the primary method for determining the 3D structure of peptides in solution.
Related Terms Ramachandran Plot X Ray Crystallography Backbone

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