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Circular Dichroism (CD) and electron paramagnetic resonance (EPR) were used to investigate the metal-binding sites of five different four-helix bundles, which have slight differences in the population of their side chains. Of the four-helix bundles, three have central dinuclear metal binding sites; two of these three also have outer dinuclear metal binding sites. The other two peptides have two identical, non-central, dinuclear metal binding sites. The CD spectra showed changes in the secondary structure of the peptides, and X-band EPR spectra of these peptides revealed the unique four peak signal of Cu(II). These findings improve our understanding of the metal binding environments of these peptides.
ContributorsCanarie, Elizabeth Rose (Author) / Allen, James (Thesis director) / Wolf, George (Committee member) / School of Mathematical and Statistical Sciences (Contributor) / School of Molecular Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
Dielectrophoresis is a separations strategy that has the potential to separate small amounts of different proteins from each other. The forces at play in the channel used for dielectrophoresis are electroosmotic flow (EOF), electrophoresis (EP), and dielectrophoresis (DEP). EOF is the force exerted on liquid from an applied potential (1). EP is the force exerted on charged particles in a uniform electric field (2). DEP is the force exerted on particles (charged and uncharged) in a non-uniform electric field (3). This experiment was focused on the testing of a new microfluidic device to see if it could improve the focusing of proteins in dielectrophoresis. It was predicted that the addition of a salt bridge would improve focusing by preventing the ions created by the electrolysis of water around the electrodes from interacting with the proteins and causing aggregation, among other problems. Control trials using the old device showed that electrolysis was likely occurring and was the causal agent for poor outcomes. After applying the electric potential for some time a pH front traveled through the channel causing aggregation of proteins and the current in the channel decreased rapidly, even while the voltage was held constant. The resistance in the channels of the control trials also slightly decreased over time, until the pH shift occurred, at which time it increased rapidly. Experimental trials with a new device that included salt bridges eliminated this pH front and had a roughly linear increase of current in the channel with the voltage applied. This device can now be used in future research with protein dielectrophoresis, including in the potential differentiation of different proteins. References: 1) Electroosmosis. Oxford Dictionary of Biochemistry and Molecular Biology. 2. Oxford University Press: Oxford, England. 2006. 2) Electrophoresis. Oxford Dictionary of Biochemistry and Molecular Biology. 2. Oxford University Press: Oxford, England. 2006. 3) Dielectrophoresis. Oxford Dictionary of Biochemistry and Molecular Biology. 2. Oxford University Press: Oxford, England. 2006.
ContributorsHayes, Katelyn Donna (Author) / Hayes, Mark (Thesis director) / Borges, Chad (Committee member) / School of Life Sciences (Contributor) / Department of Psychology (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05