|| Summary of main contributions
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
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.
of a pulsed immuno-labelling method for studying protein folding and
its application to the folding mechanism of reduced hen lysozyme.
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
- Demonstration that the recovery of native
protein during a renaturation process depends on the kinetic
competition (nowadays named "kinetic partitioning) between refolding and aggregation.
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
Folding vs aggregation
- 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
- Development of a flow-cytometry-based
method to quantify the endocytosis of ligands bound to membrane
receptors on a cell-by-cell basis.
With P. Métézeau at cell-sorter
- 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.
Working at the Beta-imager
||- 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.