157 research outputs found
Biosynthesis of cyclic peptide natural products in mushrooms
No full text"This work aims to describe cycloamanide biosynthesis and its capacity for cyclic peptide production, and to harness the pathway as a means to design and synthesize bioactive peptides and novel compounds."--From abstract.Thesis (Ph. D.)--Michigan State University. Biochemistry & Molecular Biology, 2017Includes bibliographical reference
Measuring the reduction potential of taurine:-ketoglutarate dioxygenase and biochemical analysis of a thermophilic ortholog
No full textABSTRACTMEASURING THE REDUCTION POTENTIAL OF TAURINE:&alpha-KETOGLUTARATE DIOXYGENASE AND BIOCHEMICAL ANALYSIS OF A THERMOPHILIC ORTHOLOGByCeleste Arlene WarrellThis thesis seeks to determine the reduction potential, more specifically, the midpoint potential, of the archetypal non-heme iron/&alpha-ketoglutarate dioxygenase, TauD, and to characterize a putative TauD ortholog from a moderately thermophilic bacterium. The accomplishment of these aims will expand our understanding of the mechanism of action of TauD and other members of this important enzyme superfamily. Two methods were employed to investigate the midpoint potential of TauD. Thin-layer cyclic voltammetry, an electrochemical method, was unsuccessful in directly generating a value for the midpoint of TauD. Instead, I used ultraviolet-visible spectroscopy to monitor titrations with the redox active dye methylene green to calculate the midpoint potential of Fe(III)/Fe(II)-TauD (Em of 207 ± 27 mV vs. the Ag/AgCl electrode). Binding of the co-substrate &alpha-ketoglutarate (0.5 mM) with and without the substrate taurine (0.5 mM) did not significantly shift this value (204 ± 46 mV and 210 ± 32 mV, respectively). Preliminary activity assays suggested that the recombinant Mycobacterium thermoresistibile TauD-like protein is not a taurine:\ue1-ketoglutarate dioxygenase. Ongoing studies by others are now examining an alternate function of this recombinant M. thermoresistibileprotein as a sulfate-degrading enzyme.Thesis (M.S.)--Michigan State University. Biochemistry and Molecular Biology, 2013Includes bibliographical references (pages 53-57
The distribution and dynamics of resistance genes in soil microbiomes
No full text"The soil microbiome harbors immense microbial biodiversity that encodes important functions of interest to public health. These include functional genes that encode resistance to antibiotics and arsenic. In the case of antibiotic resistance, transfer from environmental strains to pathogens is a public health risk, and arsenic resistance and metabolisms are important for bioremediation as they impact the fate of arsenic in the environment. While these resistance genes are well-characterized in vitro, the full scope of their environmental distribution, diversity, and interspecies transfer is unknown. A better understanding of the diversity and distribution of resistance genes would provide insights into the potential for mitigation of public health problems such as arsenic contamination and antibiotic resistance. The work in this dissertation used a combination of cultivation-dependent and -independent techniques to better understand the dynamics and distributions of antibiotic and arsenic resistance genes in the environment. The influence of a disturbance on microbial antibiotic resistance and arsenic related genes was investigated by examining soils overlaying an underground coal mine fire in Centralia, PA. Additionally, soil meta-analyses were used to determine broader distributions patterns of these genes. These data and methods not only provide insights into the distributions and dynamics of antibiotic resistance and arsenic related genes in soil microbiomes but also provide a framework for future studies of other functional genes."--Page ii.Thesis (Ph. D.)--Michigan State University. Microbiology, 2019Includes bibliographical references (pages 180-203
Investigation of nitrous oxide biosynthesis by a bacterial nitric oxide reductase (NOR) and an engineered NOR mimic using stable isotope ratio mass spectrometry
No full textWhile carbon dioxide (CO2) is the most prevalent greenhouse gas, nitrous oxide (N2O) is far more potent, with a global warming potential ~265 times greater than that of carbon dioxide over a 100-year period.1 Additionally, N2O is capable of destroying ozone, making it doubly concerning as a greenhouse gas. Approximately half of the N2O produced yearly is from anthropogenic sources. The largest contributor to anthropogenic N2O is the over-fertilization of agricultural soils, which fuels a host of microbial nitrogen cycling processes that produce N2O. One of these processes is denitrification, and N2O is known to be an obligate intermediate in this process. In denitrification, N2O is synthesized by an enzyme known as nitric oxide reductase (NOR). A thorough understanding of the enzymatic mechanisms by which N2O is produced is essential to mitigating anthropogenic N2O emissions. To this end, this thesis contains the examination of N2O produced by a bacterial cytochrome c NOR (cNOR) from Paracoccus dentrificans and a cNOR mimic, I107EFeBMb, using stable isotope ratio mass spectrometry (IRMS). The first chapter provides the reader with an introduction to the nitrogen cycle, the known NORs, and the basics of isotope theory. The studies on the native cNOR and I107EFeBMb are contained in the second and third chapters, respectively. Conclusions and future directions are presented in the final chapter.Thesis (M.S.)--Michigan State University. Biochemistry and Molecular Biology, 2018Includes bibliographical references (pages 75-82
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