CECILIA TOMMOS, Ph.D.
Research Assistant Professor of Biochemistry and Biophysics
Docent of Biochemistry, Stockholm University, Sweden
905 Stellar-Chance Laboratories
Ph.D. Stockholm University, Sweden (1997)
DESCRIPTION OF RESEARCH INTERESTS:
Dr. Tommos's research includes the following projects: Using model proteins and electrochemical methods to study amino-acid radical chemistry; using double-mutant cycles and high-pressure spectroscopy to study the energetics of protein cation-π interactions; exploring "forced folding" as a method for structural characterization of marginally stable proteins.
Electrochemical studies of model radical proteins.
Essentially nothing is known about the thermodynamic properties of amino-acid redox cofactors. This reflects the simple fact that the characteristically reactive and thermodynamically hot radical state is highly challenging to study in the natural systems. The "redox inert" design of the α3W model protein was specifically made to facilitate electrochemical studies at high positive potentials and, using this system, we aim to systematically characterize the thermodynamic properties of amino-acid radicals as a function of the protein environment.
Studies of cation-π interactions.
Cation-π interactions, involving the close alignment of a cationic and aromatic side-chain pair, are commonly found in proteins. However, data concerning the energetic contributions of these non-covalent interactions to the overall protein stability are quite equivocal. Again using the α3W system, we measure the strength of cation-π interactions by double-mutant cycles. We are also exploring the use of high-pressure spectroscopy to probe the strength of this type of interaction.
Protein forced folding.
Structural genomics studies have revealed that a surprising large fraction of the proteins from various genomes, including that of humans, are unfolded and/or aggregated under in vitro conditions. This is a serious deficiency considering the general desire to homology model proteins of unknown structure i.e. the database required may not be obtainable using standard crystallographic or NMR-based approaches. To relieve this apparent bottleneck, we showed that the unfolded state of a heavily mutated and unstable version of the α3W protein could be force folded into a well-defined structure by using a unique confined space approach based on reverse micelle technology. We are now in the process of exploring the potential of this confined-space approach to force fold naturally unfolded proteins. This project is conducted in collaboration with Professor Wand.