The Robert R. Dewald Summer Scholarship Award

Bob DewaldDuring his 47-year tenure at Tufts, Chemistry Professor Robert Dewald taught nearly 20,000 undergraduate and graduate students. Professor Dewald's willingness to involve his students in research, mentor undergraduates in the sciences, or lend a helping hand to those seeking his counsel made a significant impact to the Tufts education of countless alumni. In Honor of his dedication several alumni initiated the Robert R. Dewald Undergraduate Summer Scholarship Award.

You can make a gift by going to the Dewald Summer Scholarship Fund website.

To make sure your gift supports the fund, select "Arts and Sciences" under the "Select a School" dropdown menu, "Other" under "Select an Area", and type Dewald Summer Scholarship Fund followed by the amount of your gift.

For more information or for other methods of making a gift to the Dewald Summer Scholarship Fund, please contact:
Kosta Alexis, University Advancement: 617-627-4978 or Kosta.Alexis@tufts.edu


Application deadline for the 2017 Dewald Summer Scholarship - Friday, March 17th

Recipients will receive a $3,500 scholarship and $500 in supply money to carry out their research. The application should include: a description of the proposed project (no more than 2 pages) outlining the novelty of the overall project, their part in it, what they will accomplish, and how their contribution may lead to publication; the name of the chemistry faculty with whom the student will be working, a current copy of his/her transcript and a current resume. Corresponding faculty must write a letter of support, differentiating one candidate from another if multiple students from the same group apply, and including how the student’s work will be monitored.

Upon award, it is the responsibility of the awardee to submit an abstract (non-scientific) of their project. Upon completion of the work conducted over the summer, it is the responsibility of the student to provide an abstract that includes accomplishments. These documents along with the student’s picture will be posted to the department’s web page.

Submit applications and abstracts to the Chemistry Office at main.chemoffice@tufts.edu

 


 
The 2016 Robert R. Dewald Summer Scholarship Awardees


Nile Abularrage - An Enrichment Strategy for Studying Phosphorylated Proteins



Proteins are regulated by many posttranslational modifications including phosphorylation and dephosphorylation, processes that add or remove a phosphate group, respectively, acting as ‘on’ and ‘off’ switches. Although it is a very important regulatory technique, it is understudied because of the relatively low abundance of phosphorylated proteins compared to their dephosphorylated counterparts in the cell which can allow phosphoproteins to go unnoticed. Secondly, phosphorylated proteins are difficult to visualize using conventional proteomics approaches due to chemical properties associated with the phosphate groups. In order to find a solution to this problem, we turn our attention toward bacterial enzymes used by Salmonella and Shigella which have evolved in nature as a mechanism to subvert mammalian immune system attacks. These enzymes do this by irreversibly inactivating phosphorylated proteins using a mechanism termed ‘phospholyase activity.’ The phospholyase activity results in a modification that renders the previously phosphorylated protein highly active toward further chemical modification. I hope to exploit this increased activity to add chemical ‘handles’ that will allow for capture and purification of only the previously phosphorylated proteins to learn more about why and when proteins are phosphorylated in cellular states.

During my summer project, I will be working to develop an enrichment strategy for studying phosphorylated proteins. I will be using the aforementioned bacterial enzymes to alter phosphorylated proteins then determine an appropriate molecule, or handle, to further aid in their purification. The end goal of my project is to use the chemical handle I design to isolate previously phosphorylated proteins from the rest of the cellular proteins to allow us to further study protein regulation by phosphorylation and dephosphorylation.


Christopher Ivimey - Reactions of Ethylamine and Other Compounds on Copper Surfaces



When molecules absorb or stick to specific surfaces some of them can undergo chemical reactions that would otherwise rarely occur. One subset of these reactions is the coupling reaction in which the surface permits the formation of a bond between two compounds. Many of these reactions are incredibly important in a wide variety of industries as they are reliable even when performed on massive scales. When carbon dioxide and ethylamine are deposited together on a copper surface the copper permits the formation of a bond between the nitrogen of the amine and the carbon of the carbon dioxide. While this carbon-nitrogen bond forming chemistry has considerable potential in the nylon industry, very little has been done to analyze the exact products of the reaction and experiment with similar compounds.

To fill this gap in knowledge I will be examining the reactions of ethylamine and other compounds on copper surfaces. I will be using the technique temperature programmed desorption as it is the ideal technique to examine the products of surface catalyzed reactions. In this technique, the surface is cooled and then exposed to the compounds of interest. The surface is so cold almost any compound that touches it adheres. After this the surface is heated in a controlled manner giving the compounds the energy to react and giving the products the energy to leave the surface. These free products are then identified with a mass spectrometer. Using this technique I will be able to examine the products of the coupling reactions of ethylamine under various conditions and better understand the system.

 


 
The 2014 Robert R. Dewald Summer Scholarship Awardee


Francis Appeadu-Mensah -Single Molecule Array Technology for Nucleic Acid Detection. (advisor: David Walt)



Nucleic acid detection is critical for a range of applications from human genetic tests to infectious disease detection. Current methods for nucleic acid detection are typically based on Polymerase Chain Reaction (PCR). The limitation of PCR is that there is an amplification step that introduces unavoidable bias and leads to inaccurate quantification of the nucleic acid target. To overcome this limitation, the Walt laboratory has developed a Single Molecule Array (SiMoA) technology for nucleic acid detection. The SiMoA technology enables the direct detection of nucleic acid target within a femtoliter well. This extremely small reaction volume enhances the local concentration of fluorescent product and thus gives rise to a stronger signal of detection. As a result the SiMoA method achieves similar sensitivity as PCR, but with an additional advantage - the direct detection of nucleic acids avoids bias and gives more accurate quantitative results. Since nucleic acids are extremely important diagnostic targets associated with disease, being able to detect them with high sensitivity and minimal bias has the potential for diagnosing diseases.

In my summer research, I performed side-by-side comparisons between these two biochemical systems- nucleic acid SiMoA (as the innovative new technology) and PCR (as the gold standard). Results of the experiments were presented to doctors working in the Children’s Department at the Korle-Bu Teaching Hospital, the premier health care facility in Ghana. The presentation proved useful since PCR is often performed to determine whether patients under the age of eighteen months have acquired a retroviral infection. It was noted that although PCR had been quite successful at detecting the Human Immunodeficiency Virus in infants, in theory, nucleic acid SiMoA would be a more pragmatic approach towards the early detection of cancer. Given the fact that the children’s cancer unit had been established just the previous year, doctors were optimistic about the relevance of the new technology in cancer detection at the hospital. With regards to the added sensitivity of nucleic acid SiMoA in detecting nucleic acids, further experiments would have to be performed to conclusively support this theory.

 


 
The 2013 Robert R. Dewald Summer Scholarship Awardees


David Bass - Use of Combinatorial Libraries in the Development of a Sortase A Inhibitor. (advisor: Joshua Kritzer)


Antibiotic resistance is increasing at a faster rate than the development of new antibiotics. For this reason we will be examining an enzyme found in gram-positive bacteria that has been identified as a potential drug target, Sortase A. This enzyme is a protease; there is precedent for inhibiting a protease with a cyclic peptide. There is currently no viable inhibitors of Sortase A available. For this reason I am synthesizing and screening combinatorial libraries this summer in an attempt to find a cyclic peptide inhibitor of Sortase A.

I will be using solid phase synthesis technique to make all of my peptides. I am also using a method known as split and pool synthesis in order to create the combinatorial libraries. In this method I will split the resin at several points of the synthesis in order to couple several different amino acids in the same position, and then pool all of the separate pieces back together. This will result in the synthesis of hundreds to thousands of unique peptides, each confined to a single bead. Next I am screening the compounds to see if they bind Sortase A directly. Once screening is completed the beads containing the “hits” can then be identified and separated under a microscope, and analyzed by mass spectrometry in order to determine the sequence of the peptide.


Stacey Berkowitz - Chemical Analysis of Martian Meteorite Samples. (advisor: Sam Kounaves)


In 2008, the Wet Chemistry Lab aboard the Phoenix Mars Lander travelled to Mars and successfully performed the first wet chemical analysis of Martian soil. This analysis revealed the presence of approximately 1% perchlorate (ClO4-) in the martian soil. Even though ClO4- is stable under Mars conditions, the processes that produce it also produce highly oxidizing intermediary oxychlorines such as ClO- and ClO2-. These oxychlorines may be responsible for the destruction of organics on Mars' surface. In order to better understand the distribution of ClO4- on Mars I will be performing follow-up analyses of several Martian meteorites to determine whether the perchlorate is present only at the Phoenix Landing Site in the Northern plains or in similar concentrations throughout the surface of Mars.

For this project, I will be performing ion chromatographic and isotopic analyses of several martian meteorites that have been recovered in Antarctica and Morocco in order to better understand the distribution of the ClO4- and the chemical composition of the martian soil. Ion chromatography is an analytical technique that separates ions based on their charges. Isotopic ratio mass spectrometry is another analytical technique that measures the ratio of isotopes present in a sample. Both these techniques will be used to analyze the meteorite samples to determine the quantity of perchlorate and other oxychlorines that may be present. This project is critical in understanding the presence of martian organics and the geochemical evolution of Mars.

 
 


 
The 2012 Robert R. Dewald Summer Scholarship Awardees

Eriene-Heidi Sidhom - Ganglioside GM1 Tethered Analogues of Anti-Dietetic Drugs and Other Therapeutics.
(advisor: Krishna Kumar)


Sidhom

Over the summer, I synthesized molecular constructs to target G-protein coupled receptors (GPCRs). These receptors are implicated in a wide range of diseases such as diabetes, pain management, inflammation, and calcium homeostasis. In general, GPCRs induce signaling, upon binding to an agonist. This leads to increased levels of secondary messengers, such as cyclic AMP leading to downstream effects within a cell such as regulating the expression of certain genes. The goal of the project is to make endogenous agonists and antagonists of GPCRs more effective through increasing their 'effective molarity' on cellular surfaces and aim to modulate GPCR activation using membrane anchors.

In particular, I worked on the synthesis of lipid-protein constructs concentrate these targets to lipid rafts where GPCRs have been also shown to co-localize. The organic synthesis and characterization of these constructs have been carried out and will be tested in cell studies in the coming months. Earlier studies of similar lipid-protein constructs have been previously carried out in the lab with promising results and have moved towards animal studies; we anticipate publications within the coming year. In the coming year, as part my Senior Thesis, I will continue to study the trafficking pathway of particular lipids through the cell to potentially target intracellular GPCRs.


Jordan Sisel - Application of Cyclopropenium Cation Promoted Glycosylation to the Construction of alpha-G1CNAc.(advisor: Clay Bennett)


Sisel

Over the summer, I studied novel methods to synthesize the T antigen glycopeptide. The T antigen is used to raise antibodies against cancer cells, and has been shown to be exceptionally useful in cancer vaccine research. The supply of these carbohydrate molecules is limited, however, due to difficulties involved with their chemical synthesis. In particular, both the yields and selectivity of most processes used to chemically synthesize the T antigen are low. To address this issue we chose to examine the use of a new chemical glycosylation method developed in our lab, based on cyclopropenium cation activation, to synthesize this important molecule.

Our initial studies on model reactions were promising, and led to a publication I coauthored (J. M. Nogueira, et al., Eur. J. Org. Chem., 2012, 4927-4930). The method outlined in this publication was not able to directly provide the target product, the T antigen. However, observations made during this time led to the discovery of a new method for glycosidic bond formation. This method is based on thioglycoside activation along with the use of diphenylsulfoxide, trifluoromethanesulfonic anhydride, and iodide. This new method appears to be a more powerful and selective glycosylation method. Specifically, it works with a number of substrates, which the cyclopropenium cation method does not. We anticipate the publication of another manuscript based on this method will be submitted soon. Once submitted, I will return to the study of the difficult synthesis of the T antigen as part of my undergraduate research.