Imaging

@article{violette_exploring_2008,

title = {Exploring helical folding of oligoureas during chain elongation by high-resolution magic-angle-spinning (HRMAS) NMR spectroscopy},

author = {Aude Violette and Nathalie Lancelot and Alexander Poschalko and Martial Piotto and Jean-Paul Briand and Jesus Raya and Karim Elbayed and Alberto Bianco and Gilles Guichard},

doi = {10.1002/chem.200701923},

issn = {0947-6539},

year  = {2008},

date = {2008-01-01},

journal = {Chemistry (Weinheim an Der Bergstrasse, Germany)},

volume = {14},

number = {13},

pages = {3874--3882},

abstract = {The development of novel folding oligomers (foldamers) for biological and biomedical applications requires both precise structural information and appropriate methods to detect folding propensity. However, the synthesis and the systematic conformational investigation of large arrays of oligomers to determine the influence of factors, such as chain length, side chains, and surrounding environment, on secondary structure can be quite tedious. Herein, we show for 2.5-helical N,N'-linked oligoureas (gamma-peptide lineage) that the whole process of foldamer characterization can be accelerated by using high-resolution magic-angle-spinning (HRMAS) NMR spectroscopy. This was achieved by monitoring a simple descriptor of conformational homogeneity (e.g., chemical shift difference between diastereotopic main chain CH2 protons) at different stages of oligourea chain growth on a solid support. HRMAS NMR experiments were conducted on two sets of oligoureas, ranging from dimer to hexamer, immobilized on DEUSS, a perdeuterated poly(oxyethylene)-based solid support swollen in solvents of low to high polarity. One evident advantage of the method is that only minute amount of material is required. In addition, the resonance of the deuterated resin is almost negligeable. On-bead NOESY spectra of high quality and with resolution comparable to that of liquid samples were obtained for longer oligomers, thus allowing detailed structural characterization.},

keywords = {I2CT, Magnetic Resonance Spectroscopy, Molecular Structure, Solvents, Team-Bianco, Urea},

pubstate = {published},

tppubtype = {article}

}

@article{furrer_evidence_2001,

title = {Evidence of secondary structure by high-resolution magic angle spinning NMR spectroscopy of a bioactive peptide bound to different solid supports},

author = {J Furrer and M Piotto and M Bourdonneau and D Limal and G Guichard and K Elbayed and J Raya and J P Briand and A Bianco},

doi = {10.1021/ja003566w},

issn = {0002-7863},

year  = {2001},

date = {2001-01-01},

journal = {Journal of the American Chemical Society},

volume = {123},

number = {18},

pages = {4130--4138},

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.},

keywords = {Amino Acid Sequence, biomolecular, Capsid, Capsid Proteins, Epitopes, I2CT, Molecular Sequence Data, Nuclear Magnetic Resonance, Peptide Fragments, Plant, Protein Structure, Resins, Secondary, Solvents, Team-Bianco},

pubstate = {published},

tppubtype = {article}

}