DNA is arguably the most important molecule for life on Earth. Of particular interest are the mechanisms by which DNA and RNA interact with other molecules. Dr. Lee is using the vibrational spectroscopies of Raman scattering and infrared absorption to study the microscopic interaction between DNA and various ligand molecules such as daunomycin and cisplatin, two cancer drugs in clinical use. The exact strength of the interactions between the various atoms of the DNA and ligand molecule can be determined by measuring the shift in the frequencies of the vibrational modes. This information is crucial in understanding the exact mechanism by which different drugs fight cancer as well as the biologically important processes of replication and transcription. Calorimetry is used to study the binding strengths of water to DNA.
We also study hyaluronic acid (HA), the central organizing component of cartilage. We have found that the mechanical properties of HA undergo an interesting phase transition as the water of hydration is changed. We are currently performing experiments to elucidate the nature of this phase transition. We are also working to understand if this phase transition has any relevance in disease conditions such as arthritis.
The application of high pressure (on the order of 100,000 atmospheres) causes a dramatic shrinkage of the interatomic spacings within the sample. This shrinkage causes significant changes in the many-body properties of the material. For instance, an insulator can be changed into a conductor. We are using high pressure techniques to study the vibrational properties of molecular crystals as a function of pressure. Currently we are studying nucleosides in order to obtain more information about the interactions of the nucleosides with neighboring molecular units in the nucleic acids.