Evidence of Secondary Structure by High-Resolution Magic Angle Spinning NMR Spectroscopy of a Bioactive Peptide Bound to Different Solid Supports

Abstract

The structure of the 19-amino acid peptide epitope, corresponding to the 141-159 sequence of capsid viral protein VP1 of foot-and-mouth disease virus (FMDV), bound to three different resins, namely, polystyrene-MBHA, PEGA, and POEPOP, has been determined by high-resolution magic angle spinning (HRMAS) NMR spectroscopy. A combination of homonuclear and heteronuclear bidimensional experiments was used for the complete peptide resonance assignment and the qualitative characterization of the peptide folding. The influence of the chemicophysical nature of the different polymers on the secondary structure of the covalently attached FMDV peptide was studied in detail. In the case of polystyrene-MBHA and polyacrylamide-PEGA resins, the analysis of the 2D spectra was hampered by missing signals and extensive overlaps, and only a propensity toward a peptide secondary structure could be derived from the assigned NOE correlations. When the FMDV peptide was linked to the polyoxyethylene-based POEPOP resin, it was found to adopt in dimethylformamide a helical conformation encompassing the C-terminal domain from residues 152 to 159. This conformation is very close to that of the free peptide previously analyzed in 2,2,2-trifluoroethanol. Our study clearly demonstrates that a regular helical structure can be adopted by a resin-bound bioactive peptide. Moreover, a change in the folding was observed when the same peptide-POEPOP conjugate was swollen in aqueous solution, displaying the same conformational features as the free peptide in water. The possibility of studying solid-supported ordered secondary structures by the HRMAS NMR technique in a wide range of solvents can be extended either to other biologically relevant peptides and proteins or to new synthetic oligomers.

Liposomal vaccines with conformation-specific amyloid peptide antigens define immune response and efficacy in APP transgenic mice

“…To gain additional insight into the molecular structure of the polypeptide chains, MAS NMR experiments were performed (28)(29)(30). The spectral region of the peptide backbone and aromatic side chains were monitored for ACI-01 and ACI-24 when reconstituted into liposomes [supporting information (SI) Fig.…”

Comparative Investigation of the Cleavage Step in the Synthesis of Model Peptide Resins: Implications for N.ALPHA.-9-Fluorenylmethyloxycarbonyl-Solid Phase Peptide Synthesis

“…These efforts have ranged from optimizing the coupling reaction itself (through the use of efficient acylating reagents, microwave irradiation and variations in temperature) [2][3][4][5] to broadening our knowledge of the complex peptide-resin solvation process. [6][7][8][9] Predictably, methods such as nuclear magnetic resonance 10,11) and Fourier transform infrared spectroscopy 12,13) have also been tested in attempts to further improve SPPS. In our case, [14][15][16][17] we pioneered the application of the electron paramagnetic resonance (EPR) technique, which is based on the use of a previously developed amino acid-type marker.…”

Dynamic and magnetic susceptibility effects on the MAS NMR linewidth of a tetrapeptide bound to different resins

“…A complete characterization of the FMDV peptide was achieved on POEPOP resin whereas only a partial assignment was possible on Wang resin. 12 Therefore, for the POEPOP-bound peptide, relaxation becomes the dominant cause of line broadening since anisotropic magnetic susceptibility effects are almost non existent. A T 1 ( 1 H) value of 600 ms was measured for the methyl group of the Met residue, leading to a theoretical linewidth of 0.5 Hz, whereas the experimental linewidth is about 3 Hz.…”