Related Experiment Video
Updated: Jul 22, 2026
14:55
Atomic Scale Structural Studies of Macromolecular Assemblies by Solid-state Nuclear Magnetic Resonance Spectroscopy
Published on: September 17, 2017
Structure distribution in an elastin-mimetic peptide (VPGVG)3 investigated by solid-state NMR
Journal of the American Chemical Society
|April 1, 2004
Summary
Solid-state NMR reveals elastin peptides adopt two distinct structures: a compact form with a hydrogen bond and an extended, distorted beta-strand. This bimodal distribution explains the structural basis of elastin
Area of Science:
- Biophysics
- Structural Biology
- Materials Science
Background:
- Elastin, an extracellular matrix protein, provides elasticity to tissues.
- Understanding elastin's structure is crucial for elucidating the molecular mechanism of tissue elasticity.
- Previous studies lack detailed structural insights into elastin's conformational dynamics.
Purpose of the Study:
- To determine inter-residue distances and torsion angles in an elastin-mimetic peptide, (VPGVG)3, using solid-state NMR.
- To elucidate the structural basis of elastin's elasticity by analyzing peptide conformation.
- To correlate peptide structure with the mechanical properties of elastin.
Main Methods:
- Solid-state NMR spectroscopy, including 13C-15N and 13C-1H rotational-echo double-resonance (REDOR) experiments.
- Measurement of C-H and C-N distances between specific residues (V6 carbonyl and V9 amide).
- Determination of (phi, psi) torsion angles of the central pentameric unit using dipolar correlation NMR.
Main Results:
- A bimodal distribution of intramolecular distances was observed: one-third of molecules showed short distances (3.3-4.3 Å), while the rest had longer distances (~7 Å).
- Torsion angle measurements indicated predominantly extended conformations for proline (P7) and glycine (G8) residues (~150°).
- Two distinct structures were identified: a minor compact form with a V6-V9 hydrogen bond (potentially a type II beta-turn or a novel turn) and a major extended, distorted beta-strand form.
Conclusions:
- The (VPGVG)3 peptide exhibits a bimodal structural distribution, with both compact and extended conformations coexisting.
- This conformational heterogeneity, particularly around proline and glycine residues, provides insight into the molecular mechanism of elastin elasticity.
- The findings are consistent with the structural properties of native elastin, suggesting this peptide model is relevant for understanding elastin function.
More Related Videos
Related Concept Videos
01:07Nuclear Magnetic Resonance (NMR): Overview
Nuclear magnetic resonance (NMR) is a phenomenon exhibited by certain nuclei that can absorb characteristic radio frequency radiation under certain conditions. NMR has been extensively applied in molecular spectroscopy and medical diagnostic imaging. In both these applications, the molecule or subject under study is placed in a magnetic field and irradiated with radio frequency energy.
NMR spectroscopy generates a spectrum where the characteristic absorption frequencies of the sample are...
NMR spectroscopy generates a spectrum where the characteristic absorption frequencies of the sample are...
01:13¹H NMR: Complex Splitting
A proton M that is coupled to a proton X results in doublet signals for M. However, NMR-active nuclei can be simultaneously coupled to more than one nonequivalent nucleus. When M is coupled to a second proton A, such as in styrene oxide, each peak in the doublet is split into another doublet.
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied first.
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied first.
00:52¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
At room temperature, the chair conformer of cyclohexane undergoes rapid ring flipping between two equivalent chair conformers at a rate of approximately 105 times per second. These two chair conformers are in equilibrium. The rapid ring flipping results in the interconversion of the axial proton to an equatorial proton and an equatorial to the axial proton. Such interconversions are too rapid and cannot be detected on the NMR timescale. Hence, the NMR spectrometer cannot distinguish between the...
01:12Two-Dimensional (2D) NMR: Overview
The 1D NMR spectrum of large and complex molecules like natural products has complicated splitting patterns and overlapping signals, which can be easily interpreted using 2-dimensional (2D) NMR. Unlike 1D NMR, 2D NMR has two frequency axes that provide the coupling information between the nucleus A and nucleus B in a molecule. The process from which 2D spectra are obtained has four steps.
The first step is the preparation period, during which nucleus A is excited with a radiofrequency pulse.
The first step is the preparation period, during which nucleus A is excited with a radiofrequency pulse.
01:08NMR Spectroscopy: Spin–Spin Coupling
The spin state of an NMR-active nucleus can have a slight effect on its immediate electronic environment. This effect propagates through the intervening bonds and affects the electronic environments of NMR-active nuclei up to three bonds away; occasionally, even farther. This phenomenon is called spin–spin coupling or J-coupling. Coupling interactions are mutual and result in small changes in the absorption frequencies of both nuclei involved. While nuclei of the same element are involved in...
01:15¹H NMR of Conformationally Flexible Molecules: Variable-Temperature NMR
The axial and equatorial protons in cyclohexane can be distinguished by performing a variable-temperature NMR experiment. In this process, except for one proton, the remaining eleven protons are replaced by deuterium. The deuterium substitution avoids the possible peak splitting caused by the spin-spin coupling between the adjacent protons. The remaining proton flips between the axial and equatorial positions.