The RPAR peptide, a prototype C-end Rule (CendR) sequence that binds to neuropilin-1 (NRP-1), has potential therapeutic uses as internalization trigger in anticancer nanodevices. Recently, the functionalization of gold nanoparticles with CendR peptides has been proved to be a successful strategy to target the NRP-1 receptor in prostate cancer cells. In this work, we investigate the influence of two gold surface facets, (100) and (111), on the conformational preferences of RPAR using molecular dynamics simulations. Both clustering and conformational analyses revealed that the peptide backbone becomes very rigid upon adsorption onto gold, which is a very fast and favored process, the only flexibility being attributed to the side chains of the two Arg residues. Thus, the different components of RPAR tend to adopt an elongated shape, which is characterized by the pseudo-extended conformation of both the backbone and the Arg side chains. This conformation is very different from the already known bioactive conformation, indicating that RPAR is drastically affected by the substrate. Interestingly, the preferred conformations of the peptide adsorbed onto gold facets are not stabilized by salt bridges and/or specific intramolecular hydrogen bonds, which represent an important difference with respect to the conformations found in other environments (e.g. the peptide in solution and interacting with NRP-1 receptor). However, the conformational changes induced by the substrate are not detrimental for the use of gold nanoparticles as appropriate vehicles for the transport and targeted delivery of the RPAR. Thus, once their high affinity for the NRP-1 receptor induces the targeted delivery of the elongated peptide molecules from the gold nanoparticles, the lack of intramolecular interactions facilitates their evolution towards the bioactive conformation, increasing the therapeutic efficacy of the peptide.
Mazzier, D.; Grassi, L.; Moretto, A.; Aleman, C.; Formaggio, F.; Toniolo, C.; Crisma, M. Journal of peptide science Vol. 23, num. 4, p. 346-362 DOI: 10.1002/psc.2957 Data de publicació: 2017-04-01 Article en revista
We performed the solution-phase synthesis of a set of model peptides, including homo-oligomers, based on the 2-aminoadamantane-2-carboxylic acid (Adm) residue, an extremely bulky, highly lipophilic, tricyclic, achiral, Ca-tetrasubstituted a-amino acid. In particular, for the difficult peptide coupling reaction between two Adm residues, we took advantage of the Meldal's a-azidoacyl chloride approach. Most of the synthesized Adm peptides were characterized by single-crystal X-ray diffraction analyses. The results indicate a significant propensity for the Adm residue to adopt ¿-turn and ¿-turn-like conformations. Interestingly, we found that a -CO-(Adm)2-NH- sequence is folded in the crystal state into a regular, incipient ¿-helix, at variance with the behavior of all of the homo-dipeptides from Ca-tetrasubstituted a-amino acids already investigated, which tend to adopt either the ß-turn or the fully extended conformation. Our density functional theory conformational energy calculations on the terminally blocked homo-peptides (n = 2–8) fully confirmed the crystal-state data, strongly supporting the view that this rigid Ca-tetrasubstituted a-amino acid residue is largely the most effective building block for ¿-helix induction, although to a limited length (anti-cooperative effect).
The conformational preferences of the Arg-GlE-Asp sequence, where GlE is an engineered amino acid bearing a 3,4-ethylenedioxythiophene (EDOT) ring as side group, have been determined combining density functional theory calculations with a well-established conformational search strategy. Although the Arg-GlE-Asp sequence was designed to prepare a conducting polymer–peptide conjugate with excellent electrochemical and bioadhesive properties, the behavior of such hybrid material as adhesive biointerface is improvable. Results obtained in this work prove that the bioactive characteristics of the parent Arg-Gly-Asp sequence become unstable in Arg-GlE-Asp because of both the steric hindrance caused by the EDOT side group and the repulsive interactions between the oxygen atoms belonging to the backbone amide groups and the EDOT side group. Detailed analyses of the conformational preferences identified in this work have been used to re-engineer the Arg-GlE-Asp sequence for the future development of a new electroactive conjugate with improved bioadhesive properties. The preparation of this new conjugate is in progress.
Peptides homing tumor vasculature are considered promising molecular imaging agents for cancer detection at an early stage. In addition to their high binding affinity, improved tissue penetrating ability, and low immunogenicity, they can deliver targeted anticancer drugs, thus expanding therapeutic treatments. Among those, CREKA, a linear peptide that specifically binds to clotted-plasma proteins in tumor vessels, has been recently employed to design bioactive systems able to target different cancer types. Within this context, this paper explores the biorecognition event between CR(NMe)EKA, an engineered CREKA-analog bearing a noncoded amino acid (N-methyl-Glu) that is responsible for its enhanced activity, and clotted-plasma proteins (fibrin and fibrinogen) by nanomechanical detection. Specifically, the tumor-homing peptide was covalently attached via epoxysilane chemistry onto silicon microcantilever chips that acted as sensors during dynamic mode experiments. Before that, each step of the functionalization process was followed by contact angle measurements, interferometry, X-ray photoelectron spectroscopy, and atomic force microscopy, thus revealing the applied protocol as a suitable strategy. The fibrin(ogen)-binding induced by CR(NMe)EKA was detected by the resonance frequency shift of the cantilevers, and a detection limit of 100¿ng/mL was achieved for both proteins. Even though further development is required, this work reflects the promising application of emerging technologies capable of assisting in the comprehension of biological interactions and their implications in the biotechnological field.
This is the peer reviewed version of the following article: “Puiggalí, A., Del Valle, L.J., Aleman, C. and Pérez, M. (2017) Weighing biointeractions between fibrin (ogen) and clot-binding peptides using microcantilever sensors. Journal of peptide science, (23) 2: 162–171.” which has been published in final form at [doi: 10.1002/psc.2938]. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving."
Maione, S.; Fabregat, G.; del Valle, LJ.; Ballano, G.; Cativiela, C.; Aleman, C. Journal of peptide science Vol. 20, num. 7, p. 537-546 DOI: 10.1002/psc.2660 Data de publicació: 2014-07-01 Article en revista
The roughness and thickness of films formed by hybrid conjugates prepared by coupling poly(3,4-ethylenedioxythiophene) and synthetic amino acids bearing a 3,4-ethylenedioxythiophene group in the side chain have been significantly increased using a new synthetic approach. This procedure also provoked a more effective incorporation of the amino acid at the end of the polymer chains, as has been reflected by the electronic and electrochemical properties. Although the surface polarity of all these materials is similar to that of formamide, the hydrophilicity of the conjugates is higher than that of the conducting polymer. The surface energy of all the investigated systems is dominated by the dispersive component, even though the role played by the polar contribution is more important for the conjugates than for the conducting polymer. On the other hand, all the prepared materials behave as bioactive matrices. The electrochemical response of the conjugates coated with cells reflects the electro-compatibility of these two-component substrates. Thus, the ability to exchange charge reversibly of all conjugates increases considerably when they are coated with cellular monolayers, which has attributed to favorable interactions at the interface formed by the conjugate surface and the cellular monolayer. Copyright (c) 2014 European Peptide Society and John Wiley & Sons, Ltd.
This special issue originates from the Symposium C entitled
‘Peptide-based materials: from nanostructures to applications’,
held during the 2010 Spring Conference of the European
Materials Research Society (Strasbourg, June 5–11,
Septic shock is a leading cause of mortality in intensive
care patients, and no specific drugs are as yet available
for its treatment. Therefore, new leads ar
e required in order to increase the numbe
r of active molecules that may develop into
efficacious and safe LPS-neutralizing mol
ecules during pre-clinical stages. We used pe
ptides, derived from the binding regions
of known LPS-binding proteins, as scaffolds
to introduce modifications at the amino aci
d level. Structure–activity relationship
studies have shown that these modifications generate highly acti
ve peptides. Thus, from a bioactive peptide with an initial 16
amino acid residues, a tetrapeptide sequence was determined. A
fter inserting this sequence in a Cys cyclic peptide, it showed
the same biological activity as the parent peptide. This sequenc
e could provide the basis for the design of small molecules with