Unravelling the mechanisms of a protein refolding process based on the association of detergents and co-solvents.
; ; et al
in Journal of peptide science : an official publication of the European Peptide Society (2016)
A new technique associating the detergent Sodium Dodecyl Sulphate (SDS) and an alcohol-type co-solvent has been set up, showing an unexpected efficiency to refold several types of soluble or membrane ... [more ▼]
A new technique associating the detergent Sodium Dodecyl Sulphate (SDS) and an alcohol-type co-solvent has been set up, showing an unexpected efficiency to refold several types of soluble or membrane proteins. The present contribution deepens the fundamental knowledge on the phenomena underlying this process, considering the refolding of two model peptides featuring the main protein secondary structures: alpha-helix and beta-sheet. Their refolding was monitored by fluorescence and circular dichroism, and it turns out that: (i) 100% recovery of the folded structure is observed for both peptides, (ii) the highest the SDS concentration, the more co-solvent to be added to recover the peptides' native structures, (iii) a high alcohol concentration is required to alter the SDS denaturing properties, (iv) the co-solvent performance relies on its specific lipophilic-hydrophilic balanced character, (v) the size of the micelle formed by the detergent does not enter the process critical parameters, and (vi) increasing the salt concentration up to 1 M NaCl has a beneficial impact on the process efficiency. These mechanistic aspects will help us to improve the method and extend its application. Copyright (c) 2016 European Peptide Society and John Wiley & Sons, Ltd. [less ▲]Detailed reference viewed: 27 (5 ULg)
In silico predictions of 3D structures of linear and cyclic peptides with natural and non-proteinogenic residues.
Beaufays, Jérôme ; Lins, Laurence ; Thomas, Annick et al
in Journal of Peptide Science : An Official Publication of the European Peptide Society (2012), 18(1), 17-24
We extended the use of Peplook, an in silico procedure for the prediction of three-dimensional (3D) models of linear peptides to the prediction of 3D models of cyclic peptides and thanks to the ab initio ... [more ▼]
We extended the use of Peplook, an in silico procedure for the prediction of three-dimensional (3D) models of linear peptides to the prediction of 3D models of cyclic peptides and thanks to the ab initio calculation procedure, to the calculation of peptides with non-proteinogenic amino acids. Indeed, such peptides cannot be predicted by homology or threading. We compare the calculated models with NMR and X-ray models and for the cyclic peptides, with models predicted by other in silico procedures (Pep-Fold and I-Tasser). For cyclic peptides, on a set of 38 peptides, average root mean square deviation of backbone atoms (BB-RMSD) was 3.8 and 4.1 A for Peplook and Pep-Fold, respectively. The best results are obtained with I-Tasser (2.5 A) although evaluations were biased by the fact that the resolved Protein Data Bank models could be used as template by the server. Peplook and Pep-Fold give similar results, better for short (up to 20 residues) than for longer peptides. For peptides with non-proteinogenic residues, performances of Peplook are sound with an average BB-RMSD of 3.6 A for 'non-natural peptides' and 3.4 A for peptides combining non-proteinogenic residues and cyclic structure. These results open interesting possibilities for the design of peptidic drugs. Copyright (c) 2011 European Peptide Society and John Wiley & Sons, Ltd. [less ▲]Detailed reference viewed: 41 (6 ULg)
Tilted peptides: a structural motif involved in protein membrane insertion?
Lins, Laurence ; Brasseur, Robert
in Journal of Peptide Science : An Official Publication of the European Peptide Society (2008), 14(4), 416-22
Tilted peptides are short hydrophobic protein fragments characterized by an asymmetric distribution of their hydrophobic residues when helical. They are able to interact with a hydrophobic/hydrophilic ... [more ▼]
Tilted peptides are short hydrophobic protein fragments characterized by an asymmetric distribution of their hydrophobic residues when helical. They are able to interact with a hydrophobic/hydrophilic interface (such as a lipid membrane) and to destabilize the organized system into which they insert. They were detected in viral fusion proteins and in proteins involved in different biological processes involving membrane insertion or translocation of the protein in which they are found. In this paper, we have analysed different protein domains related to membrane insertion with regard to their tilted properties. They are the N-terminal signal peptide of the filamentous haemagglutinin (FHA), a Bordetella pertussis protein secreted in high amount and the hydrophobic domain from proteins forming pores (i.e. ColIa, Bax and Bcl-2). From the predictions and the experimental approaches, we suggest that tilted peptides found in those proteins could have a more general role in the mechanism of insertion/translocation of proteins into/across membranes. For the signal sequences, they could help the protein machinery involved in protein secretion to be more active. In the case of toroidal pore formation, they could disturb the lipids, facilitating the insertion of the other more hydrophilic helices. [less ▲]Detailed reference viewed: 29 (2 ULg)