Next Section Meeting
Date: Thursday, April 12
Place: Berry Auditorium (C101)
Glaske Center for Engineering Science and Technology
Dinner: On your own (refreshments will be provided)
Time: Poster Session beginning at 7:00 P.M.
Undergraduate Poster Session (abstracts received as of April 2)
Inorganic toxic metals, polyaromatic hydrocarbons, and pathogens are common contaminants found in aquatic and terrestrial environments. Here we report an experimental study of the effect of toxic metal ions on photosensitized singlet oxygen generation for photodegradation of common polycyclic aromatic hydrocarbons derivatives (PAH derivatives) contaminants consisting of three benzenoid rings, such as Anthracene‐9,10‐dipropionic acid disodium salt (ADPA), and two benzenoid rings, such as 1,5dihydroxynapthalene (DHN) by using water soluble cationic meso‐tetra(N‐methyl‐4‐pyridyl)porphine tetrachloride (TMPyP) as a singlet oxygen photosensitizer. In addition, we investigated the effect of toxic metal ions on singlet oxygen generation for photoinactivation of E.coli bacteria by using the same TMPyP singlet oxygen photosensitizer. The photodegradation of electron‐rich ADPA and DHN by TMPyP‐generated singlet oxygen (1O2) was examined and the rates of photodegradation of ADPA and DHN were calculated to be (1.50 ± 0.26) × 10‐3 s‐1 and (6.62 ± 0.50) × 10‐4 s‐1. The presence of s‐block metals ions, such as Na+, K+, and Ca2+ showed no change of the rate of photodegradation of ADPA or DHN by TMPyP generated 1O2. However, in the presence of heavy metals such as Cd2+, Cu2+, Hg2+, Zn2+, and Pb2+, we observed a dramatic change in the photodegradation of ADPA and DHN. Interestingly, the photodegradation of electron‐rich ADPA and DHN were observed to increase rapidly in the presence of heavy metal cadmium (II) ions (Cd2+). The obtained photodegradation rate constants of ADPA and DHN in the presence of Cd2+ ions were (3.91 ± 0.20) × 10‐3 s‐1 and (7.18 ± 0.35) × 10‐4 s‐1, respectively. Strikingly, the photodegradation of ADPA was moderately reduced in the presence of zinc ions (Zn2+) and almost completely inhibited in the presence of mercury (II) ions (Hg2+) and copper (II) ions. Similarly, DHN photodegradation was significantly slowed down in the presence of Hg2+ and Cu2+ ions. Finally, we tested the photoinactivation of E.coli by singlet oxygen from TMPyP in the presence of dissolved toxic metal ions such as Cd2+, Cu2+, Hg2+, Zn2+, and Pb2+ ions. A complete inhibition of growth of E.coli was observed when E. coli solutions were irradiated with TMPyP and heavy metal ions particularly, Cd2+, Hg2+, Zn2+, and Pb2+ ions. Interestingly, toxic copper ions followed a similar trend as seen in photodegradation of DHN and ADPA. A significantly slow inhibition of E.coli’s growth was observed in the presence of copper ions (Cu2+ ions) and TMPyP. A substantial dark toxicity for mercury ions and a complete dark toxicity for zinc ions against E.coli were observed in the presence of TMPyP. This result is demonstrating the fact that dissolved toxic metal ions except copper ions in the presence of TMPyP have a strong influence on generation of 1O2 for photoinactivation of E.coli bacteria as well as killing E. coli under dark conditions.
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This study focused on estimating the presence of bacterial species within La Nana Creek in proximity to Stephen F. Austin State University. The method used for this study involved the U.S. Environmental Protection Agency (USEPA) Method 1604: Total Coliforms and Escherichia coli in Water by Membrane Filtration Using a Simultaneous Detection. A 50 mL of freshwater sample was collected from four different sites along La Nana Creek and filtrated through a membrane filter via gravity filtration and rolled over a MI agar plate to determine a total coliforms and E. coli count within the site of collection. After colony count, some colonies were selected for sequencing to prove the presence of E coli or to determine the genus of colonies. The overall presence of E. coli in the water samples was very low (less than 3.5 colony per MI agar plate on average). Based on the sequencing data, all blue colored colonies were proven to be E. coli except for site I sample I. This colony appears to be a Klebsiella pneumoniae; however, that could be a result of contamination during colony PCR since the beige colored colony was growing in a proximity to the blue colony. The prevailing family of bacteria present within samples was Enterobacteriaceae, commonly found within intestines of animals as well as in soil and water. The only other family present was Pseudomodaceae which is found in all types of environment.
La Nana Creek is one of two springs that surround Nacogdoches, TX. La Nana Creek starts southwest of Lake Naconiche, conjoining with several other bodies of water along its path, and becomes part of the Angelina River. This body of water eventually ends in the Gulf of Mexico which may contribute to the dead zone. La Nana Creek water and soil samples were studied for the determination of selected metals (Ag, Ba, Be, Bi, Cd, Co, Cr, Cs, Cu, Ga, In, Li, Mn, Mo, Ni, Pb, Rb, Sr, Tl, V, and Zn) from September 2016 through November 2017 (12 samples at each site). Sampling sites consisted of NE Stallings Drive, East College Street, Main St., and Martin Luther King Jr. Blvd. Samples were analyzed using the EPA protocol for digesting water and soil samples. Samples were acidified, digested (total recoverable), and filtered to remove residue. Results indicate that the water samples had Ba, Mn, Sr, and Zn at measurable amounts (greater than 10 ppb for majority of samples) while soil samples had these species at measurable amounts as well as Cr, Ni, Pb, Rb, and V. Soil samples have a much higher metal concentration than water samples except for Sr. Soil results tended to decrease from North to South in the creek for all metal concentrations due to soil variation while water samples tended to have similar results at all locations. All samples analyzed were found to have metal concentrations typical for creek water and soil type and well below WHO and EPA allowable values.
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All living organisms contain enzymes which carry out biological reactions which produce substances with a specific three dimensional shape. Enantiomers are two molecules that are mirror images of each other just as hands are mirror images of each other. It is well known in the pharmaceutical world that one of the enantiomers (one of the mirror‐image molecules) has a positive biological effect while the other can be harmful or have no effect. Currently, any potential pharmaceutical that could exist as enantiomers must have each enantiomer tested for biological activity prior to FDA approval. In our laboratory, we have focused on one particular reaction in which enzymes in vegetables catalyze a reaction of benzofuranyl methyl ketone (BMK) to benzofuranylethanol (BMA). BMA can have two different three dimensional arrangements, so mirror image molecules are possible. The two enantiomers are designated S‐BMA and R‐BMA. Several vegetables have been utilized to determine which can catalyze this reaction, as well as to determine whether the various vegetables produce both enantiomers or only a single enantiomer. Several vegetables (carrot, parsnip, and celery) produce only one of the enantiomers, the S‐isomer. However, potatoes and radishes produce a mixture of the R‐ and S‐isomer, with the potato producing nearly equal amounts of both. Previous work in the laboratory has shown that the S‐BMA produced from carrots has antimicrobial properties, inhibiting the growth of bacteria as well as yeast. Initial studies indicate the mixture of S‐ and R‐BMA from potatoes has less potent antimicrobial activity than the pure S‐BMA produced by carrots. Studies are underway to more fully assess the antimicrobial property of the mixture of the R‐and S‐isomer and compare to the antimicrobial property of the pure S‐isomer produced by carrots.
A method to efficiently produce sulfonamide derivatives from a variety of substituted benzaldehydes is reported. This method is a modification of a method reported by Helmuth Gilow (J. Chem. Educ., 1979, 56 (6), 419‐420), which was unsuccessful in our hands. Sulfanilamide can be condensed with a number of substituted benzaldehydes in good yields by refluxing in 1‐propanol for an hour. Reduction of the resulting imines with sodium borohydride worked well for most of the imines. We are currently investigating “one‐pot” procedures to accomplish both steps without isolation of the imine intermediate. The substituted sulfonamides will be tested for antimicrobial activity. If all of the parts of the experiment can be optimized, this would be a nice interdisciplinary organic chemistry/microbiology project for our chemistry and biology students, which could illustrate the drug discovery process, as well as structure activity relationships of drugs.
Examining Strategies for Improving Catalytic Activity of Enzymes Encapsulated in Virus‐Like Particles
Christy Hjorth*1, Andrea Irias1, Jessica Bird1, Dustin Patterson1, Trevor Douglas2
1 Department of Chemistry & Biochemistry, The University of Texas at Tyler
2 Department of Chemistry, Indiana University
Encapsulation of enzymes into protein cage structures holds promise for developing catalytic nanomaterials and better understanding of enzyme function in cellular environments. This research presented evaluates the encapsulation of enzymes inside protein cage virus‐like particles (VLPs) derived from bacteriophage P22 comparing a rapid in vivo encapsulation strategy with a temporally controlled expression strategy to improve the overall activity of enzymes encapsulated inside the P22 VLP. Results from the rapid in vivo encapsulation strategy showed greatly reduced kinetic activity in comparison with the temporally controlled strategy, suggesting that maturation of an enzyme before encapsulation is necessary.
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Protein cages are ubiquitous in nature and present useful nanomaterials for applications ranging from drug delivery to the construction of nanoelectronics. Among protein cages, virus‐like particles (VLPs), which are derived from the protein shell of viruses but lack pathogenic components, are particularly intriguing for constructing nanomaterials due to their stability and well‐studied molecular assembly and structures. The VLP derived from the HK97 bacteriophage self assembles from a single coat protein to form a 55 nm particle which will not enter mammalian cells. This characteristic makes the HK97 VLP a potentially ideal platform for targeted drug delivery. The research presented will discuss the design and molecular modification of the HK97 VLP toward producing a drug delivery "smart bomb".
Encapsulation of Elastase inside the P22 Virus‐like Particle
Department of Chemistry & Biochemistry
The University of Texas at Tyler
Elastase is a protein that is secreted by the pathogen Pseudomonas aeruginosa that is responsible for tissue damage and infection by the pathogen in the human host. Elastase has been implicated in activation of the EGFR signaling pathway and there is an interest in understanding its involvement and mechanism of EGFR activation. The results presented here are for the encapsulation and characterization of Pseudomonas aeruginosa elastase enzyme in the P22 virus‐like particle (VLP). By encapsulating the elastase enzyme inside the VLP biocontainer, preventing direct contact of the enzyme with the cell surface, but allowing free exchange of soluble substrates into the VLP through 2 nm pores in the protein wall, we seek to examine the mechanism for the activation of the EGFR pathway. In addition, the elastase‐VLP holds potential for the development of a vaccine providing protection against Pseudomonas aeruginosa.