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Hyperthermophilic proteins are of great interest in both the academic and industrial world in understanding how these proteins are capable of retaining their biological activity under such harsh environmental conditions. This thesis studies a tetrabrachion stalk domain from Staphylothermus marinus, know as Right Handed Coiled Coil (RHCC). This protein is of interest due to its extreme thermostability and its affinity for heavy metals. We aim to better understand the reason for the extreme thermal stability of the protein and to take advantage of the proteins affinity for heavy metals with a view to developing a novel approach to bioremediate Hg2+, a major environmental pollutant. Our results clearly indicated that the protein is more thermostable in alkaline conditions in comparison to acidic conditions. This observation can be explained by careful inspection of the high resolution structure. Our data also clearly show that RHCC is able to bind ionic mercury compounds such as mercury nitrate and dipotassium mercury iodide.

Gaucher’s disease (GD) is an autosomal recessive lysosomal storage disorder which is caused by a mutation in the gene encoding acid β-glucocerebrosidase (GBA, EC 3.2.1.45). Deficient activity in GBA leads to a wide variety of clinical phenotypes, including visceral symptoms such as hepatospenomegaly as well as neurological symptoms. Current enzyme replacement therapy is effective in treating visceral symptoms but cannot cross the blood-brain barrier to target neurological manifestations. Another drawback to current therapy is the high cost to patients due to present protein expression strategies. Recently, protein transduction domains, such as the synthetic PTD4 domain, have been proposed as a therapeutic strategy for drug delivery to the central nervous system. In the present study, we use an economical yeast expression system, Pichia pastoris, to produce a recombinant fusion protein GBA-PTD4, and semi-preparative hydrophobic interaction chromatography and gel filtration chromatography for purification. Results show that final preparations are near homogenous, with GBA-PTD4 accounting for approximately 76% of total protein and only one major contaminant. A cell line expressing GBA without a transduction domain was also created in anticipation of further cellular uptake studies. Future research will focus on large scale enzyme expression in fermentation systems and more direct purification methods such as immunoaffinity chromatography for better protein recovery. / Graduate

Certain strains of hydrophobic bacteria are known to play critical roles in petroleum-related applications. The aim of this study was to investigate how hydrophobic bacteria in their stationary phase could adsorb onto the hexadecane-water interface and alter its mechanical properties. The two strains of bacteria used in forming the interfacial films were Acinetobacter venetianus RAG-1 (a Gram-negative bacterium) and Rhodococcus erythropolis 20S-E1-c (Gram-positive). Experiments at two different length scales (millimetre and micrometre) were conducted and the results were compared. In addition, a simple flow experiment was designed in a constricted channel and the results were related to the intrinsic mechanical properties of bacteria-adsorbed films. On the millimetre scale, using the pendant drop technique, the film interfacial tension was monitored as the surface area was made to undergo changes. Under static conditions, both types of bacteria showed no significant effect on the interfacial tension. When subjected to transient excitations, the two bacterial films exhibited qualitatively similar, yet quantitative distinct rheological properties (including film elasticities and relaxation times). Under continuous reduction of surface area, the RAG-1 system showed a “paper-like” interface, while the interface of the 20S-E1-c system was “soap film-like.” These macroscopic observations could be explained by the surface ultrastructures of the two cell strains. On the micrometre scale, using the micropipette technique, colloidal stability of the bacteria-coated oil droplets was examined through direct-contact experiments. Both types of bacteria were seen to function as effective stabilizers. In addition, the adsorbed bacteria also interacted with one another at the interface, giving rise to higher order 2-D rheological properties. A technique of directly probing the mechanical properties of the emulsion drop surfaces revealed that (a) the films behaved as purely elastic sheets, and (b) with a reduction in cell concentration in the aqueous phase, less oil was emulsified, but the elastic moduli of the adsorbed films remained unchanged. These results are in contrast to the above millimetre-scale study. Therefore the rheological properties of these bacteria-adsorbed films appear to be length scale-dependent. An oil displacement experiment was designed to investigate the flow behaviour of micron-scale emulsion drops in a constricted channel. The qualitative results can be correlated with the interfacial rheological properties and may have valuable relevance to the study of multiphase flow through constricted channels in porous rocks (e.g. in MEOR operations). / Chemical Engineering

In this study, we developed a facile method for preparing a superhydrophobic paper surface using a layer-by-layer deposition of polydiallyldimethylammonium chloride (polyDADMAC) and silica particles, followed by a fluorination surface treatment with 1H,1H,2H,2H-perfluorooctyltriethoxysilane (POTS, CF3(CF2)5CH2CH2Si(OC2H5)3). The wood fiber products prepared in this study had contact angles of water greater than 150 degree and sliding angles less than 5 degree. Besides their high water repelling property, the superhydrophobic paper products kept a high tensile strength at high relative humidity condition. The superhydrophobic paper products also showed high resistance to bacterial contamination.

Very little is known about the hydrophobic proteins of psychrophiles and their roles in cold adaptation. In light of this situation, methods were developed to analyse the hydrophobic proteome (HPP) of the model psychrophilic archaeon Methanococcoides burtonii. Central to this analysis was a novel differential solubility fractionation procedure, which resulted in a significant increase in the efficiency of resolving the HPP. Over 50% of the detected proteins were not identified in previous whole cell extract analyses, and these underwent an intensive manual annotation process producing high quality functional assignments. Utilising the functional assignments, biological context analysis of the HPP was performed, revealing novel and often unique biology. The analysis acted as a platform for differential proteomics of the organism???s response to both temperature and substrate using stable isotope labelling. The results of which revealed that low temperature growth was associated with an increase in the abundance of surface and secreted proteins, and translation apparatus. Conversely, growth at a higher temperature was associated with an increase in the abundance of general protein folding machinery and indications of an oxidative stress response, emphasising that the temperature for maximum growth rate is stressful. Through investigation of the response of M. burtonii to substrate it was found that growth on methanol was stressful, and its low energy yield resulted in an increase in the abundance of energy conserving systems. The extracellular polymeric substance (EPS) and morphology of M. burtonii was also investigated with respect to both temperature and substrate, using a number of techniques in microscopy. It was found that the EPS was comprised of proteins, sugars and RNA, and that growth at different temperatures resulted in the production of EPS that displayed significantly different properties on dehydration, thus indicating compositional variation. When cells were grown on methanol they took on highly irregular shapes and had electron transparent inclusions. The observations from the ultrastructural analysis were contemplated with respect to the proteomic findings, revealing novel avenues of research. This study has highlighted the roles of hydrophobic proteins in cold adaptation biology, and the value of comprehensive proteomics for the examination of adaptation in microorganisms

Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Bert Bras; Committee Member: David Rosen; Committee Member: Jeannette Yen

Thesis (Ph. D.)--Florida State University, 2005. / Advisor: Dr. John G. Dorsey, Florida State University, College of Arts and Sciences, Dept. of Chemistry and Biochemistry. Title and description from dissertation home page (June 15, 2005). Document formatted into pages; contains xiv, 112 pages. Includes bibliographical references.

Thesis (M. S.)--Chemical Engineering, Georgia Institute of Technology, 2008. / Committee Chair: Yulin Deng; Committee Member: Jeffery S. Hsieh; Committee Member: Sujit Banerjee; Committee Member: Zhong Lin Wang.

abstract: Durable, cost-effective, and environmentally friendly anti-icing methods are desired to reduce the icing hazard in many different industrial areas including transportation systems, power plants, power transmission, as well as offshore oil and gas production. In contrast to traditional passive anti-icing surfaces, this thesis work introduces an anti-icing coating that responds to different icing conditions by releasing an antifreeze liquid. It consists of an outer porous superhydrophobic epidermis and a wick-like underlying dermis that is infused with the antifreeze liquid. This bi-layer coating prevents accumulation of frost, freezing fog, and freezing rain, while conventional anti-icing surfaces typically work only in one of these conditions. The bi-layer coating also delays condensation on the exterior surface at least ten times longer than identical system without antifreeze. It is demonstrated that the significant delay in condensation onset is due to the integral humidity sink effect posed by the hygroscopic antifreeze liquid infused in the porous structure. This effect significantly alters the water vapor concentration field at the coating surface, which delays nucleation of drops and ice. It was demonstrated that with a proper design of the environmental chamber the size of the region of inhibited condensation and condensation frosting around an isolated pore, as well as periodically spaced pores, filled by propylene glycol can be quantitatively predicted from quasi-steady state water vapor concentration field. Theoretical analysis and experiments revealed that the inhibition of nucleation is governed by only two non-dimensional geometrical parameters: the pore size relative to the unit cell size and the ratio of the unit cell size to the thickness of the boundary layer. It is demonstrated that by switching the size of the pores from millimeters to nanometers, a dramatic depression of the nucleation onset temperature, as well as significantly greater delay in nucleation onset can be achieved. / Dissertation/Thesis / Doctoral Dissertation Mechanical Engineering 2017