DSBC – Dynamics of Complex Biomolecular Systems

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Research topics in DSBC group

Research activity in the DSBC group is mainly involved in physical organic chemistry and analytical chemistry, mostly of α-amino acids, (poly)peptides and their derivatives. We are especially interested in both (i) a physico-chemical approach of the reactivity of biomolecules and/or their precursors or derivatives, and (ii) the development of innovating separative science methodologies applying to polymers. DSBC research topics are organised according to four major directions, hereafter detailed.

1. Prebiotic chemistry, systems chemistry and the emergence of life

Topic currently granted by the Agence Nationale de la Recherche through the PeptiSystems project (ANR-14-CE33-0020, 2014–2019).

The transition towards the living state is studied through a dynamic approach based on the application of physicochemical principles. The Darwinian description of biological evolution can thus be integrated into a wider view starting from far-from-equilibrium chemical systems including replicators or autocatalytic loops (Systems chemistry). We are involved in the study of thermodynamic constraints governing these dissipative systems capable of giving rise to emergent properties. Concerning the experimental aspect, our team focuses its interest on the chemistry of amino acids with the aim of demonstrating how certain properties (e.g. homochirality) can be selected by the transformation of high-energy derivatives (α-amino acid N-carboxyanhydrides (NCAs) or 5(4H)-oxazolones for instance). Their interaction with nucleotides is susceptible of generating chemical intermediates closely related to the biochemical protein synthetic pathways and then likely to have been involved in the emergence of translation.

Keywords:

Prebiotic chemistry ; α-Amino acids ; Peptides ; α-Amino acid N-carboxyanhydrides ; 5(4H)-Oxazolones ; Peptides/nucleotides co-evolution ; Emergence of homochirality ; Origin of life ; Evolution ; Protométabolism ; Energy sources ; Dynamic kinetic stability ; Complexification

People involved:

Permanent staff: Laurent Boiteau (CNRS Associate Scientist / CR), Jean-Christophe Rossi (UM Associate Professor / MCF), Robert Pascal (CNRS emeritus Senior Scientist / DR ém.)
Temporary staff: (n/a)

2. Capillary electrokinetic separation methods

This research topic deals with the methodological development of the different modes of capillary electrophoresis (free solution, gel, micellar electrochromatography, isoelectric focusing, isotachophoresis, frontal analysis, and bidimensional) and Taylor dispersion analysis. Our research is especially aiming the development of new methodologies for the physicochemical characterization of biopolymers, polyelectrolytes, nanoparticles and microorganisms (bacteria). Among others, the following physicochemical characteristics are studied: effective charge, counter-ion condensation rate, hydrodynamic radius, molar mass, hydrophobicity (log P), isoelectric point, stoichiometry and binding constant of complexation.

Keywords:

Capillary electrophoresis ; Taylor dispersion analysis ; Physicochemical characterisation ; (bio)Polymers ; Polyelectrolytes ; Proteins ; Nanoparticles ; Effective charge ; Counter-ion condensation ; Hydrodynamic radius ; Electrophoretic mobility.

People involved:

Permanent staff: Hervé Cottet (UM Professor), Joseph Chamieh (UM Associate Professor / MCF), Laurent Leclercq (CNRS Associate Scientist / CR), Isabelle Desvignes (UM Associate Professor / MCF), Jean-Philippe Biron (CNRS Technical Engineer / IE), Philippe Gonzalez (CNRS Assistant Engineer / AI)
Temporary staff: Laura Dhellemmes (PhD Student / ANR), Sébastien Roca (PhD Student / MESR), Chutintorn ‘Nan’ Somnin (PhD Student / FR/TH grant)

3. Physicochemical study of polyelectrolyte complexes

This research topic deals with the physicochemical study of polyelectrolyte complex formation and their use for biomedical, pharmaceutical or analytical applications. One of our main objectives aims at investigating the influence of physicochemical parameters (ionic strength, pH, nature, charge density and architecture of the polyelectrolyte) on the formation of polyelectrolyte complexes (size, surface charge, stoichiometry of the complex, selectivity in molar mass, ionic strength of complex dissociation). We are also investigating the relationship between the binding constant of oppositely charged polyelectrolyte, the physicochemical characteristics of interacting (polymer) partners, and the ionic strength of the medium.

Keywords:

Polyelectrolyte complexes ; Coacervates ; Association constants ; Polyplexes ; Physical chemistry.

People involved:

Permanent staff: Laurent Leclercq (CNRS Associate Scientist / CR), Hervé Cottet (UM Professor), Joseph Chamieh (UM Associate Professor / MCF), Philippe Gonzalez (CNRS Assistant Engineer / AI)
Temporary staff: Xiaoling Leclercq (post-doc), Sébastien Roca (PhD Student / MESR), Laura Dhellemmes (PhD Student / ANR)

4. Synthetic polypeptides, biomimetic and supramolecular chemistry

This topic is dedicated to peptides and peptide polymers and their physical chemistry in water; having been recently associated with the molecular recognition approach, it extends and widens a historical interest of the group, namely the elaboration of synthetic processes with a low environmental impact in the chemistries of α-amino acids and peptides. This topic is aimed at elaborating molecules or synthetic macromolecules, and more specifically branched (DGL: dendgrigraft of (poly)lysine) or cyclic polypeptides involving natural or non natural amino acids. Through the chemical functionalization of these scaffolds and the study of their interaction with substrates of biological interest, we target applications in the fields of e.g. ion exchange, reversible sequestration of transition metal ions, organocatalysis, drug delivery, biosensors for the detection of biomarkers of diseases… Other investigations in relationship with this topic involve the study of catalytic efficiency in water (intramolecular general-acid base catalysis).

Keywords:

Peptides ; Polypeptides ; Chemistry in water ; Sustainable development ; Non-covalent interactions ; Host-guest complexes ; Biosensors ; Sequestrating agents ; Organocatalysis.