Category: M. Amblard

Quantitative MALDI-MS Binding Assays: An Alternative to Radiolabeling

ChemMedChem, 2016, Volume: 11, Issue: 23, Pages: 2582-2587, DOI: 10.1002/cmdc.201600447

M. Rossato,  G. Miralles, C. M’Kadmi, M. Maingot, M. Amblard, B. Mouillac, D. Gagne, J. Martinez, G. Subra, C. Enjalbal, S. Cantel, 

Abstract

Radiolabeling of ligands is still the gold std. in the study of high-affinity receptor-ligand interactions. In an effort toward safer and simpler alternatives to the use of radioisotopes, we developed a quant. and highly sensitive matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) method that relies on the use of chem. tagged ligands designed to be specifically detectable when present as traces in complex biol. mixts. such as cellular lysates. This innovative technol. allows easy, sensitive detection and accurate quantification of analytes at the sub-nanomolar level. After statistical validation, we were able to perform pharmacol. evaluations of G protein-coupled receptor (V1A-R)-ligand interactions. Both satn. and competitive binding assays were successfully processed.

A new way to silicone-based peptide polymers

Angewandte Chemie, 2015, Volume: 54, Issue: 12, Pages: 3778-3782,  DOI: 10.1002/anie.201411065

S. Jebors, J. Ciccione, S. Al-Halifa, B. Nottelet, C. Enjalbal, C. M’Kadmi,  M. Amblard, A. Mehdi, J. Martinez, G. Subra

Abstract

We describe a new class of silicone-contg. peptide polymers obtained by a straightforward polymn. in water using tailored chlorodimethylsilyl peptide blocks as monomeric units.  This general strategy is applicable to any type of peptide sequences, yielding linear or branched polymer chains composed of well-defined peptide sequences.

Turning Peptide Sequences into Ribbon Foldamers by a Straightforward Multicyclization Reaction

Angewandte Chemie, International Edition, 2015, Volume: 54, Issue: 47, Pages: 13966-13970, DOI: 10.1002/anie.201506955

V. Martin, B. Legrand, L. L. Vezenkov, M. Berthet, G. Subra, M. Calmes, J-L. Bantignies, J. Martinez, M. Amblard

Abstract

The conformational control of mol. scaffolds allows the display of functional groups in defined spatial arrangement.  This is of considerable interest for developing fundamental and applied systems in both the fields of biol. and material sciences.  Peptides afford a large diversity of functional groups, and peptide synthetic routes are very attractive and accessible.  However, most short peptides do not possess well-defined secondary structures.  Herein, we developed a simple strategy for converting peptide sequences into structured γ-lactam-contg. oligomers while keeping the amino acids side chain diversity.  We showed the propensity of these mols. to adopt ribbon-like secondary structures.  The periodic distribution of the functional groups on both sides of the ribbon plane is encoded by the initial peptide sequence.

Unprecedented Chain-Length-Dependent Conformational Conversion Between 11/9 and 18/16 Helix in α/β-Hybrid Peptides

Angewandte Chemie, 2014, Volume: 53, Issue: 48, Pages: 13131-13135, DOI: 10.1002/anie.201407329

B. Legrand, C. Andre, L. Moulat, E. Wenger, C. Didierjean, E. Aubert, M. Averlant-Petit, J. Martinez, M. Calmes, M. Amblard

Abstract

α,β-Hybrid oligomers of varying lengths with alternating proteogenic α-amino acid and the rigid β2,3,3-trisubstituted bicyclic amino acid ABOC residues were studied using both x-ray crystal and NMR soln. structures.  While only an 11/9 helix was obtained in the solid state regardless of the length of the oligomers, conformational polymorphism as a chain-length-dependent phenomenon was obsd. in soln.  Consistent with DFT calcns., short oligomers adopted an 11/9 helix, whereas an 18/16 helix was favored for longer oligomers in soln.  A rapid interconversion between the 11/9 helix and the 18/16 helix occurred for oligomers of intermediate length.

Heating and microwave assisted SPPS of C-terminal acid peptides on trityl resin: the truth behind the yield

Amino Acids, 2013, Volume: 45, Issue: 6, Pages: 1395-1403, DOI: 10.1007/s00726-013-1604-z

C. Echalier, S. Al-Halifa, A. Kreiter, C. Enjalbal, P. Sanchez, L. Ronga, K. Puget, P. Verdie, M. Amblard, J. Martinez, G. Subra

Abstract

Despite correct purity of crude peptides prepd. on trityl resin by Fmoc/tBu microwave assisted solid phase peptide synthesis (Fmoc = 9-fluorenyl-methoxycarbonyl), surprisingly, lower yields than those expected were obtained while prepg. C-terminal acid peptides.  This could be explained by cyclization/cleavage through diketopiperazine formation during the second amino acid deprotection and third amino acid coupling.  However, we provide here evidence that this is not the case and that this yield loss was due to high temp. promoted hydrolysis of the 2-chloro-trityl ester, yielding premature cleavage of the C-terminal acid peptides.

Mixed Oligoureas Based on Constrained Bicyclic and Acyclic β-Amino Acids Derivatives: On the Significance of the Subunit Configuration for Folding

Source: Chemistry – A European Journal, 2013, Volume: 19, Issue: 50, Pages: 16963-16971,  DOI: 10.1002/chem.201302829

C. Andre, B. Legrand, L. Moulat, E. Wenger, C. Didierjean, E. Aubert, M. Averlant-Petit, J. Martinez, M. Amblard, M. Calmes

Abstract

The combination of a nonfunctionalized constrained bicyclo[2.2.2]octane motif along with urea linkages gave a highly rigid 2.512/14 helical system both in soln. and the solid state.  The authors aimed at developing stable and functionalized systems as promising materials for biol. applications in studying the impact of this constrained motif and its configuration on homo and heterochiral mixed-oligourea helix formation.  Di-, tetra-, hexa-, and octa-oligoureas alternating the highly constrained bicyclic motif of (R) or (S) configuration with acyclic (S)-β3-amino acid derivs. were constructed.  CD, NMR expts., and the x-ray crystal structure of the octamer unequivocally proved that the alternating heterochiral R/S sequences form a stable left-handed 2.5-helix in contrast to the mixed (S/S)-oligoureas, which did not adopt any defined secondary structure.  The (-)-synclinal conformation around the Cα[n.63743]Cβ bond of the acyclic residues, although sterically less favorable than the (+)-synclinal conformation, was imposed by the (R)-bicyclic amino carbamoyl (BAC) residue.  This highlighted the strong ability of the BAC residue to drive helical folding in heterochiral compds.  The role of the stereochem. of the BAC unit was assessed and a model was proposed to explain the misfolding of the S/S sequences.

Dipeptide mimic oligomer transporter mediates intracellular delivery of Cathepsin D inhibitors: a potential target for cancer therapy

J Control Release. 2013 Oct 28;171(2):251-7. doi: 10.1016/j.jconrel.2013.07.017. Epub 2013 Jul 27.

Maynadier M, Vezenkov LL, Amblard M, Martin V, Gandreuil C, Vaillant O, Gary-Bobo M, Basile I, Hernandez JF, Garcia M, Martinez J.

Abstract

Implication of the intracellular proteolytic activity of Cathepsin D (CathD), a lysosomal aspartyl-protease overexpressed in numerous solid tumors, has been evidenced on tumor growth. Its intracellular inhibition by potent inhibitors such as pepstatin constitutes a relevant but challenging molecular target. Indeed the potential of pepstatin as a therapeutic molecule is hampered by its too low intracellular penetration. We addressed this limitation by designing and developing a bioconjugate combining a pepstatin derivative with a new vector of cell penetration (CPNP) specifically targeting the endolysosomal compartment. We showed that this pepstatin conjugate (JMV4463) exhibited high anti-proliferative effect on tumor cell cultures via intracellular CathD inhibition and altered cell cycle associated with apoptotic events in vitro. When tested in mice xenografted with breast cancer cells, JMV4463 delayed tumor emergence and growth.

Helical oligomers of thiazole-based γ-amino acids: synthesis and structural studies

Angew Chem Int Ed Engl. 2013 Jun 3;52(23):6006-10. doi: 10.1002/anie.201302106

Mathieu L, Legrand B, Deng C, Vezenkov L, Wenger E, Didierjean C, Amblard M, Averlant-Petit MC, Masurier N, Lisowski V, Martinez J, Maillard LT

Abstract

9-Helix: 4-Amino(methyl)-1,3-thiazole-5-carboxylic acids (ATCs) were synthesized as new γ-amino acid building blocks. The structures of various ATC oligomers were analyzed in solution by CD and NMR spectroscopy and in the solid state by X-ray crystallography. The ATC sequences adopted a well-defined 9-helix structure in the solid state and in aprotic and protic organic solvents as well as in aqueous solution.