Professor Rizk receives teaching award

Assistant Professor Shahir Rizk was hired in 2015 to help with our expanding biochemistry chemistry. His sharp research skills and natural charisma quickly attracted a team of student researchers that seems to work non-stop. But if there was any doubt that his teaching abilities were are as sharp as his research skills, they've been put to rest because last week it was announced that Rizk was awarded a Trustee's Teaching award for, what else, excellence in teaching. While Shahir is well-known in the department for teaching junior-senior level biochemistry lecture and laboratory, he also teaches students in their first semester (freshman general chemistry discussion) and their last semester (chemistry senior seminar). Congratulations, Rizk!

2018 IU South Bend Undergraduate Research Conference

Last Friday, students from all over the campus gathered at Weikamp in the morning and early afternoon to present research and creative works from the past year. As usual, our department was well-represented; this year our students contributed two talks and three posters. Pictured above-left is biochemistry major Maggie Fink with her mother on her right arm, while pictured above-right we have fellow biochemistry major Michele Costantino. Further down we see biology major Keon Jones shown with Associate Vice Chancellor (former organic chemistry professor) Doug McMillen. Keon presented his poster earlier this month at MoLSMAP in Missouri (click here for abstract). Jones and Costantino tied for the best poster presentation from the crowd of science and non-science posters.

And finally we find chemistry majors David Aupperle and Abigail Praklet - who both gave talks - pictured with biochemistry professor Shahir Rizk (who moderated the science session). They also traveled out of state in early April to present their work, but they went to NCUR in Oklahoma (click here for abstracts). Praklet's efforts won her the award for best talk in the science session which was an excellent way to cap her summer-fall-spring research adventure with Muna.

But all of our student researchers - whether they presented at the conference or not - deserve acknowledgement for their research efforts and have gained a valuable experience that other students may have yet to claim.  If you are interested in research, please don't hesitate to ask about it. You can get the student point of view from fellow classmates - or visit one of your favorite professors to see what is happening outside of class.

Self Assembly of Novel Proteins Using Maltose Binding Protein and Engineered fABs
Maggie Fink, Professor Shahir Rizk

Many proteins undergo a large conformational change upon binding to a ligand. This conformational shift can expose protein surfaces previously shielded in the unbound state. A class of proteins that exhibits this conformational change is the bacterial periplasmic binding proteins. Each member of this family of proteins binds to a specific ligand, resulting in a shift from an open (unbound) to a closed (bound) conformation. Maltose binding protein undergoes this conformational change in response to maltose binding and transitions from an open to a closed form. To characterize the thermodynamics of these transitions and lock MBP into specific conformations, synthetic antibodies were designed to bind to MBP and screened in different maltose conditions to target both open and closed conformations. Three of these antibodies were isolated, one of which was found to bind to the open form of MBP endosterically (7O) and the other two, D1 and A1, bind to the closed form allosterically and peristerically. The aim of my project has been to construct a novel protein fusion where MBP and one of antibodies identified in the previous research are fused together. In this way the engineering proteins will potentially self-assemble into a nanostructure in the presence or absence of maltose, depending on the specificity of the antibody to the conformation of MBP. Once each of the three fusion proteins have been successfully cloned, expressed and purified, testing will be carried out to determine if a higher order complex can form in response to ligand addition or removal as a trigger.

The Effects of Metal Cofactors on Adenosine Deaminase Activity
Michele Costantino, Maggie Fink, Sandy Ho, Professor Shahir Rizk

Adenosine deaminase (ADA) is a zinc-dependent enzyme that converts adenosine to inosine as part of the purine degradation pathway. In humans, mutations in ADA are associated with severe combined immunodeficiency (SCID), an often fatal syndrome, due to accumulation of adenosine. This leads to B- and T-cell death, compromising the ability of the patient to fight infections. Previous work has shown that enzymatic activity depends on zinc concentration; however, at greater than 1:1 ratio, Zn can act as a negative allosteric effector of ADA activity. Other divalent cations — such as Co²⁺, Cu2+, Mn2+, and Cd²⁺ — can act as competitive or non-competitive inhibitors of the purified human enzyme. Additional studies indicate that Hg²⁺ inhibits crude ADA extracts from zebrafish at high concentrations. To characterize human ADA, kinetic studies with purified enzyme were conducted using direct colorimetric assays. Under optimal conditions, the rate of reaction was used to determine the K_M and k_cat of the uninhibited enzyme. The K_M and k_cat values were also obtained in the presence of coformycin, a known competitive inhibitor. The activity of ADA was measured in the presence of various divalent cations and Hg²⁺ was found to have the most profound negative effect on ADA activity. The inhibition of ADA by Hg2+ was found to be concentration dependent. This is the first study where the effect of Hg²⁺ on purified human enzyme was determined.

Students give research talks in Oklahoma

From April 4 to April 7, chemistry majors David Aupperle and Abigail Praklet attended the National Conference for Undergraduate Research (NCUR) at the University of Oklahoma in Oklahoma City. Both students gave oral presentations describing their research with analytical professor Grace Muna. The fact that each of their efforts spanned more than one semester or summer of work is a testament to their dedication and love of chemistry. Aupperle and Praklet had a wonderful time at the conference (travel was supported by a SMART travel grant) and we are proud to have them represent our department and university. The titles of their talks and abstracts are given below.
 

Electrochemical Detection of Estrogenic Compounds Using Palladium Nanoparticle Modified Electrodes

David Aupperle, Professor Grace Muna  

Chemical pollution in water is one of the major environmental problems in today’s world. Polluted water poses a threat to the aquatic organisms and human health. The pollutants such as estrogenic phenolic compounds (EPCs) need to be monitored constantly to control their impact on the environment and the ecosystem. These EPCs can be found in fresh water from waste treatment facility effluents as well as agricultural runoffs. Although the concentrations these compounds are typically low in the ng/L range, they have been found to feminize male fish and disrupt human endocrine function. Electrochemical detection provides an alternative to other analytical methods because it has attractive attributes such as high sensitivity, less expensive instrumentation, ease of sample preparation and field deployable. This work utilized the unique properties of electrodes modified with metal nanoparticles. The nanoparticles circumvent the electrode fouling seen on bare electrodes during the electro-oxidation of phenolic compounds. In the present work, glassy carbon and gold electrodes were modified with palladium nanoparticles to catalyze the electro-oxidation of EPCs. The modified electrodes exhibited good catalytic properties, good response precision and stability. For example, 50 consecutive measurements for 100 mcM estriol solution using palladium modified gold electrode gave a %RSD of 5.3%, indicating good reproducibility and response stability exhibited by the modified electrode. Future directions will be to couple the modified electrode to flow injection analysis and high-performance liquid chromatography. Results from the analytical performance of palladium modified glassy carbon and gold electrodes towards the catalytic oxidation of EPCs will be presented.

Developing a Sensitive Stripping Voltammetric Method to Detect Lead in Water and Soil

Abigail Praklet, Keon Jones, Joseph Williamson, Professor Grace Muna 

Lead is one of the most toxic heavy metal in the environment. Its presence is due to human activities notably, lead in gasoline, lead-based paint, lead-containing pesticides, lead in ammunition and sinkers, and incinerator ash or water from lead pipes. Lead poisoning can cause a number of adverse human health effects, but it is particularly detrimental to the neurological development of growing children. Therefore, frequent testing and precise monitoring of Pb in soil and water is important to assess and control lead contamination. We hereby report on developing a stripping voltammetric method using glassy carbon electrodes modified with bismuth nanoparticles (GC-BiNPs) to detect lead in drinking water and soil. Voltammetric stripping measurements have historically utilized mercury in the forms of hanging mercury drop and mercury film electrode to measure heavy metal ions. This is mainly because clean surfaces can be easily be regenerated with a new mercury drop. However, because of mercury toxicity and risks associated with its disposal its use as an electrode material for stripping measurements is severely restricted. We’re utilizing the unique properties of bismuth such as its ability to form alloys with different metals, to develop a sensitive method to detect lead. Preliminary results show that using GC-BiNPs we can detect low levels of lead down to one part per billion in water. The research findings on the stripping voltammetric method development will be presented.

Student presents research poster in Missouri

Biology major, Keon Jones, travelled to Missouri a couple weeks ago to attend the two-day (March 23 & 24) MoLSAMP (Missouri Louis Stokes Alliance for Minority Participation) Undergraduate Research Symposium. His poster describes research done last summer with chemistry student Abigail Praklet under the guidance of Professor Grace Muna. Harnessing the power of electrochemistry to develop methods to analyze the components and concentrations of solutions is standard practice and led to the development of pH meters long ago. But Jones' project takes a relatively new twist by incorporating nanoparticles of bismuth into the electrodes of the detection unit to increase sensitivity to lead. Jones' poster and presentation were well received at the symposium and we are proud to have him represent both the biology and chemistry departments, as well as the entire campus. Jones plans to continue researching this summer, but this time under an REU at another university studying molecular biology as his attention turns toward life after IU South Bend using his upcoming biology major. The abstract for his poster is given below.

A Sensitive Electrochemical Method to Determine Lead in Water and Soil
Keon Jones, Abigail Praklet, Professor Grace Muna

Lead is one of the most toxic heavy metal in the environment. Its presence is due to human activities such as the use of leaded gasoline before it was banned and lead in paint in older homes. Lead poisoning can cause a number of adverse human health effects but it’s particularly detrimental to the neurological development of growing children. Therefore, frequent testing and precise monitoring of Pb in the soil and water is important to assess and control lead contamination. We hereby report on developing a sensitive electrochemical method by using glassy carbon electrodes modified with bismuth nanoparticles (GC-BiNPs) to detect lead in drinking water and soil. Preliminary results show that with GC-BiNPs can detect low levels of lead down to 1 parts per billion in water. The developed method will be employed to detect lead in drinking water and soil. Preliminary results on the electrochemical method development will be presented.

Adjunct professors honored for 10 years of service

 

Adjunct professors George Nazaroff and Rita Harnish were honored this afternoon for 10 years of service to the university as instructors in our department. Nazaroff teaches the introduction  to chemistry lecture course for health science majors (CHEM-C 101), while Harnish typically teaches the accompanying laboratory class (CHEM-C 121). Adjunct faculty are vital to the operation of our department as they teach approximately half of our classes at the freshman level.  We are extremely grateful to all of our adjunct faculty for their excellent instruction of our students. Special thanks to Nazaroff and Harnish for laboring 10 years with us - and we hope that they will continue to teach at IU for many years to come.