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Heitz Group Research Projects

Microheterogeneous Media...
A wide variety of polar molecules, such as proteins, enzymes, dyes, etc, can be hosted in the water pool of reverse micelles. Further, it is well known that a molecule's local microenvironment has a significant impact on it's physicochemical properties, which can change significantly depending on the amount of water present in the water pool. In the case of proteins, For example, the ability of an enzyme to retain functionality depends strongly on the surrounding environment. Entrapment may substantially alter the capability of the enzyme to function properly, if at all. Thus, solvation of these species within the water pool is highly dependent on the amount of water that is present.

Proteins...
Protein binding to polymer surfaces is not well understood. Specifically, we are interested in the lysozyme sorption/desorption process. A distribution of protein binding is observed ranging from proteins that are irreversibly bound to a polymer to those that appear to bind reversibly with no mal effects upon desorption.

We are using a two-pronged approach to this system. First, we wish to use the tryptophan (trp) residues as an intrinisic fluorescence signal source. However, since lysozyme contains six trp residues, each in its own microenvironment within the protein, the contributions to the total signal from each trp is not clear. To deal with this problem, we seek to mutate the trp residues such that we have only one remaining residue. We are working this project collaboratively with Prof. Rey Sia in the Biology Department as part of the Merck AAAS Grant Project. Second, we are attempting to covalently attach an extrinsic fluorophore to the protein via the disulfide bridges. The labeling chemistry of acrylodan to free thiols has been documented. But again there are difficulties in this approach since lysozyme has four disulfide bridges. Upon examination of lysozyme's crystal structure it appears that accessibility of the bridges will aid in limited labeling.

Ionic Liquids...

Supercritical Fluids...
Another interest of our group lies in the area of supercritical fluid technology. Supercritical fluids have gained much attention in the past few decades. We are focusing on determining the behavior of the unique solute/solvent interactions that occur when one is near to the critical point. Armed with a molecular-level understanding of the physicochemical properties of a fluid, we can begin to probe the effects of supercritical fluids on chemical reactions.