Domain                   Summary of main contributions
Enzymology - First optical and chemical identification of enzyme-bound intermediates in the catalytic cycle of bacterial tryptophane synthase (TSase).

- Functional and structural properties of omega- complemented beta-galactosidase

 X ray structure of Tryp. Synthase
Immunochemistry - Design and application of ELISA-based methods for measuring the affinity and rates of association and dissociation of a monoclonal antibody and its cognate antigenic protein in solution.

- Design of a pulsed immuno-labelling method for studying protein folding and its application to the folding mechanism of reduced hen lysozyme.
         Lysozyme epitopes
Lysozyme epitopes (yellow-red and
 green-blue) monitored kinetically
Mechanisms of protein folding - First demonstration of the existence of autonomously folding regions (currently named "domains") in large proteins.

- First identication and characterization of a sequence of intermediate steps in the folding of the beta-subunit of tryptophane synthase, thus
demonstrating that protein folding does not obey a simple "two state model".

- First identification and characterization of an early folding intermediate, named the "pre-molten globule", resulting from the very rapid hydrophobic collapse of the polypeptide chain.

- Demonstration that the refolding of an unfolded protein can proceed through alternate pathways.

- Characterization by fast kinetics methods of the secondary structure of early intermediates formed within the first 4 milliseconds of the folding process.

- Demonstration that the recovery of native protein during a renaturation process depends on  the kinetic competition (nowadays named "kinetic partitioning) between refolding and aggregation.
 Far UV CD kinetics
Kinetics of lysozyme folding as seen by far UV circular dichroism
Mechanisms of protein aggregation - Demonstration that the aggregates formed during protein renaturation result from native-like, yet illegitimate, specific interactions between folding intermediates. Rather than involving distinct regions of a unique polypetide chain as in productive folding, they take place between distinct polypeptide chains, thus leading to insoluble multimers.      Aggregates
           Folding vs aggregation
Cell biology - Development of a procedure for the isolation of a unique species of mouse chromoses, and its applications to the mouse chromosomes X, Y and 21. This procedure is based on the extraction o the chromosomes from mouse strains bearing multiple Robertsonian translocations, followed by flow-cytometry sorting of the desired chromosomes.

- Development of a flow-cytometry-based method to quantify the endocytosis of ligands bound to membrane receptors on a cell-by-cell basis.
 at cell-sorter
With P. Métézeau at cell-sorter
Technical developments
- Analytical ultracentrifugation: Development of a method for measuring the molecular weight of unfolded polypeptide chains in the presence of concentrated guanidinium-chloride.

- Radioactivity imaging: Development in collaboration with Nobel laureate Georges Charpak of the Beta-Imager, an ultra-sensitive, very low background, radioactivity scanner for low energy radiation emitters (C14, H3, ...) specifically designed for biological research.

- Fast kinetics monitoring of circular dichroism: Development, in collaboration with two french industrial companies (Bio-Logic and Jobin-Yvon), of a flow/stopped-flow rapid mixing device coupled to a spectrodichrograph. Among many other applications, this apparatus enabled us to monitor the kinetics of formation of protein secondary structures from as soon as 4 milliseconds after the initiation of the folding process.

- Infrared spectroscopy: Development of a procedure to record the infrared spectrum of proteins using an ATR (Attenuated Total Reflectance) attachment, which greatly simplifies and improves protein infrared spectroscopy.

- flow-cytometry: First implementation in France of a fluorescence-activated cell-sorter; design of a "vacuum concentrator" that enables in situ hybridization on samples directly sorted on a filter.

The Beta-imager
     Working at the Beta-imager

FTIR Sprectra of 3 proteins   
Industrial applications - production of therapeutic proteins: several industrial processes used to reactivate insoluble proteins produced by genetically engineered cells are based on renaturation protocols developed in our laboratory.

- development of an anti-aging cosmetic product: invention of the use of liposomes to combat cell aging and development, in collaboration with Parfums Christian Dior, of the anti-aging cream CAPTURE for skin treatment.