Translational diffusion of cyclic peptides measured using pulsed-field gradient NMR

Area of Science:

• Biochemistry
• Structural Biology
• Drug Discovery

Background:

• Cyclic peptides are valuable scaffolds for drug discovery and design.
• Structural characterization of cyclic peptides is crucial for their development.
• Noninvasive methods are needed for efficient characterization.

Purpose of the Study:

• To explore pulse-field gradient (PFG) NMR experiments for characterizing cyclic peptide diffusion properties.
• To measure diffusion coefficients and hydrodynamic radii of various cyclic peptides.
• To assess the utility of PFG NMR in understanding cyclic peptide behavior in solution.

Main Methods:

• Diffusion coefficient measurements using PFG NMR experiments.
• Utilized internal standards (dioxane, acetonitrile, DSS) for hydrodynamic radius evaluation.
• Applied in silico predictions for comparison with experimental data.
• Investigated self-association of the cyclic peptide kB2.

Main Results:

• Experimentally determined hydrodynamic radii correlate with molecular weight and in silico predictions.
• Demonstrated the utility of 2,2-dimethyl-2-silapentane-5-sulfonic acid (DSS) as an internal standard.
• Showed that the cyclic peptide kB2 forms concentration-dependent oligomers.
• Confirmed the broad applicability of diffusion measurements in cyclic peptide structural biology.

Conclusions:

• PFG NMR is a powerful, noninvasive tool for characterizing cyclic peptide diffusion and molecular shape.
• Diffusion measurements provide insights into molecular weight, size, and self-association behavior.
• This approach facilitates structural biology studies and aids in the drug discovery of cyclic peptides.