Novel Research on Metalloproteins

Molly L. Croteau
Chemistry PhD Candidate ’15 | Dartmouth College

The graduate and undergraduate students in the Wilcox lab at Dartmouth College are using isothermal titration calorimetry (ITC) and differential scanning calorimetry (DSC) to conduct research and learn about thermodynamics. The syringes that Molly Croteau received with her 2012 Hamilton Product Grant will facilitate sample loading to these instruments for two years. Molly has generously shared her story as an example of the amazing things being done with the support from Hamilton Company and the Syringe Product Grant program.

Here at Dartmouth College, the Wilcox lab prides itself on studying the interactions between metals and proteins. Proteins are the tiny machinery of the cells within our bodies which work to keep us alive. Many metals, such as zinc, iron, and copper, are essential to living organisms, and they help plants, animals, bacteria, and fungi to carry out these everyday functions. Some metals play a stabilizing role and provide structure to proteins, while others play a catalytic role and help perform the necessary chemical reactions. Recognizing how these metals and proteins interact with one another can provide insight into an overall mechanism and a general understanding of the fundamental science behind some of these metalloproteins.

The two main techniques we use to determine these interactions are isothermal titration calorimetry (ITC) and differential scanning calorimetry (DSC). ITC measures the heat of a binding event, or when a metal and protein come together, and DSC measures the heat of an unfolding event, or when the protein is cooked to a high temperature and aggregation occurs (like the cooking of an egg turns the protein in the translucent egg whites to an opaque white color). Both of these techniques look at how the metal is interacting with the protein in the case of attaching to the protein (ITC) or keeping the protein together (DSC). Like most scientific instruments, the ITC and DSC require a syringe to load the sample.

The Wilcox lab was awarded a generous grant from Hamilton in 2013 which provided us with enough loading syringes for both the ITC and DSC to last two years. Our lab has an average of five graduate students and six undergraduate students using the ITC and DSC on a daily basis; performing experiments 24 hours a day. We also provide instrument time and training to various undergraduate physical and biophysical chemistry teaching labs during the academic year. On top of our own use, our instruments are sought after from many collaborators from Dartmouth and other institutions such as Bates College in Maine, the University of Queensland in Australia, and Université de Montréal in Canada. Since the awarding of the Hamilton syringe grant in 2013, we have used the syringes to publish numerous papers about metal-protein research including: : cobalt, cadmium, and zinc binding to organophosphate-degrading enzymes, zinc-stabilization of the insulin hexamer, and zinc binding to form the insulin hexamer. Research soon to be published that has been conducted since 2013 includes copper binding to proteins such as azurin and human antioxidant homologue 1 (HAH1), zinc and lead binding to metallothionein, and mercury interactions with merylase B. In just two short years, the syringes from Hamilton have provided a means to conduct all this novel research, and we thank Hamilton for supporting our science!