The College of Arts and Sciences presented "Constructing Enzyme Mimics: Designing New Water-Soluble Catalysts for Environmental, Medicinal, and Defense Applications" on February 13th, 2008. The event was part of the Dean's Seminar Series held in Disque Hall. Dr. Elizabeth Papish, an assistant professor in the Department of Chemistry, spoke. She explained the process of designing enzyme mimics in bioinorganic chemistry. Approximately two-dozen people attended the lecture.
Papish is the founder of the Papish Research Group, which strives to design new water-soluble ligands specifically for breaking down pesticides. From 2003 to 2007, the group was based at Salisbury University in Maryland until Papish came to Drexel.
During the seminar, Papish explained her research in terms that the audience could understand, even going as far as using K-Nex pieces for examples. Papish explained that a ligand is a molecule that binds metals. Focusing on inorganic synthesis (the process of inorganically binding metals), Papish described how biology inspired the process. In 1972, Ronald Breslow of Columbia University started the process of biomimetic chemistry by copying how biological systems work.
Papish works towards constructing enzymes, which serve as a catalyst to speed up a reaction. "We need reactions to take place in seconds rather than days," Papish said. However, enzymes are selective. The "Lock and Key" Model explains this selectivity. Enzymes have "pockets" for the right shape of a reactant. Papish's research focuses on the question, "Can we make a molecule that has a shape like this so we can do this?"
Reactions require a great amount of energy to happen. Utilizing enzymes requires less energy. Papish wants to look at an enzyme and copy its structure in order to mimic the efficiency of a natural reaction while making a low energy pathway. "Why reinvent the wheel?" Papish asks. "We can learn from nature." She used the Wright Brothers as an example: they watched birds to eventually build the first airplane.
After a molecule fits into the enzyme and the reaction happens, the enzyme kicks out the reaction since it no longer fits. Breslow tried to mimic this by physically bending his "key" whereas the enzyme finds its molecules alone. However, Breslow's chemical bond would become stuck instead of kicking out the reaction. This caused Breslow's reaction to only happen once instead of multiple times.
Papish and her fellow researchers tried to make a structural mimic of enzymes. This means that the mimic looks like an enzyme but does not function like it just like mimics that work like enzymes do not always look like it. She wants to be able to use her enzymes repeatedly instead of having Breslow's "stuck" reaction. She used an analogy about having a fight with a significant other to explain this. "You didn't want your boyfriend coming into your house so you put crazy glue in your lock."
The Papish Research Group works towards designing a better catalyst for reactions. They would like to break down pesticides used in agriculture that persist for long periods of time (detoxify). Eventually, this process could be applicable towards defense since it may break down chemical warfare agents. It may even develop an antidote for pesticide poisoning and for soldiers.
They would like to design a structural and functional enzyme mimic and study the mechanism. However, the compound needs to be water-soluble so the "lock and key" will get unstuck. At Drexel, they are trying to vary the size but are unsure as to which will work. The group is performing a balancing act to find ligands.
Papish closed her lecture with a question and answer period and acknowledging the work of Sean Gardner and Jessica Bongiovanni—two Drexel students. She also thanked ACS Petroleum Research Fund, Salisbury University, and Drexel University for funding her research.
