NMR studies of acyl chain-protein interactions

An approach employing heteronuclear NMR is presented for monitoring the interactions between long-chain fatty acids and proteins which are involved in their synthesis and intracellular transport. Two naturally occurring fatty acids, hexadecanoic (palmitic) and cis-9-10-methylene-hexadecanoic (MHA) acids were labeled using a biosynthetic scheme with 13C acetate as a source. The biosynthetic incorporation of 13C from a two carbon source resulted in sequential pairs of 13C atoms in the product. When combined with double quantum spectroscopy, a highly efficient suppression of natural abundance background resonances results. Proton-detected two and three-dimensional experiments which correlate double quantum carbon chemical shifts with proton shifts were developed to resolve and assign chemical shifts of the selectively detected cis-9,10-methylene hexadecanoic acid (MHA) and palmitic acid in sodium dodecyl sulfate (SDS) micelles.A subset of the experiments was applied to a complex between MHA and rat adipocyte lipid binding protein (ALBP), a protein involved in intracellular fatty acid transport. With the use of double quantum spectroscopy, we were able to selectively observe and assign chemical shifts to all 13C enriched pairs of resonances in the MHA-ALBP complex. Changes in chemical shifts between micelle and protein-bound states are interpreted in terms of protein-induced conformational preferences for the bound fatty acid. Comparison with x-ray crystallographic data on similar protein-fatty acid complexes suggests that non-linear fatty acid conformations observed in the crystal structure are preserved when the complex is examined in solution.Similar double quantum experiments were successfully applied to palmitic acid covalently coupled to Escherichia coli acyl carrier protein (ACP), a protein cofactor in fatty acid synthesis. Carbon-13 chemical shifts were once again used to analyze the conformation of the acyl chain. The chain was found to have an increase in gauche character at several positions, suggesting a bent conformation in the bound state. In addition, 13C filtered cross-relaxation experiments were conducted. Cross relaxation data localized the methyl terminus of the acyl chain to a binding pocket in ACP consisting of phenylalanine-50, tyrosine-71 and isoleucine-72. These data are interpreted using the known structure of octanoyl-ACP and previous models for acyl chain binding to suggest that the thioester bond may protrude from the protein complex as the chain is lengthened in order to facilitate enzyme catalyzed reactions necessary for fatty acid synthesis

Correlation Between NDE Measurements and Physical Properties of Copper Powder Metallurgy Components

Square D, a world leader in the manufacturing of electrical components and systems, needed to insure it was using only high quality powdered metal (PM) components in one of its ’ line of circuit breakers products. Low strength powdered metal components had been detected by routine destructive testing practices which subsequently rejected entire lots of product. Although the occurrence of a failure was infrequent, Square D felt that improvements in both the design of the part and method of inspection could be implemented. As a result, the part design was improved which made all of the parts acceptable all of the time with respect to break strength level. Square D was still troubled by the fact that, even though all of the parts were now acceptable, there was still a very low percentage of parts that exhibited lower than average strength

Small lakes in big landscape : multi-scale drivers of littoral ecosystem in alpine lakes.

In low nutrient alpine lakes, the littoral zone is the most productive part of the ecosystem, and it is a biodiversity hotspot. It is not entirely clear how the scale and physical heterogeneity of surrounding catchment, its ecological composition, and larger landscape gradients work together to sustain littoral communities. A total of 113 alpine lakes from the central Pyrenees were surveyed to evaluate the functional connectivity between littoral zoobenthos and landscape physical and ecological elements at geographical, catchment and local scales, and to ascertain how they affect the formation of littoral communities. At each lake, the zoobenthic composition was assessed together with geolocation, catchment hydrodynamics, geomorphology and topography, riparian vegetation composition, the presence of trout and frogs, water pH and conductivity. Multidimensional fuzzy set models integrating benthic biota and environmental variables revealed that at geographical scale, longitude unexpectedly surpassed altitude and latitude in its effect on littoral ecosystem. This reflects a sharp transition between Atlantic and Mediterranean climates and suggests a potentially high horizontal vulnerability to climate change. Topography (controlling catchment type, snow coverage and lakes connectivity) was the most influential catchment-scale driver, followed by hydrodynamics (waterbody size, type and volume of inflow/outflow). Locally, riparian plant composition significantly related to littoral community structure, richness and diversity. These variables, directly and indirectly, create habitats for aquatic and terrestrial stages of invertebrates, and control nutrient and water cycles. Three benthic associations characterised distinct lakes. Vertebrate predation, water conductivity and pH had no major influence on littoral taxa. This work provides exhaustive information from relatively pristine sites, and unveils a strong connection between littoral ecosystem and catchment heterogeneity at scales beyond the local environment. This underpins the role of alpine lakes as sensors of local and large-scale environmental changes, which can be used in monitoring networks to evaluate further impacts

Correlation Between NDE Measurements and Physical Properties of Copper Powder Metallurgy Components

Square D, a world leader in the manufacturing of electrical components and systems, needed to insure it was using only high quality powdered metal (PM) components in one of its ’ line of circuit breakers products. Low strength powdered metal components had been detected by routine destructive testing practices which subsequently rejected entire lots of product. Although the occurrence of a failure was infrequent, Square D felt that improvements in both the design of the part and method of inspection could be implemented. As a result, the part design was improved which made all of the parts acceptable all of the time with respect to break strength level. Square D was still troubled by the fact that, even though all of the parts were now acceptable, there was still a very low percentage of parts that exhibited lower than average strength.</p

Čínská zahraniční pomoc a investice ve Střední Asii: Důsledky pro vztahy mezi Čínou a Ruskem v geopolitické perspektivě

This thesis examines China's foreign aid, trade and government-sponsored investment activities in Central Asia from 2001 to 2014, asking and answering the question if any implications on Sino-Russian relations occurred as a result. As China continued to experience sustained economic growth, its development disbursements internationally began to expand as well. This work attempts to analyze the size and scope of these disbursements from China into Central Asia to see if it has impacted Sino-Russian relations utilizing the theoretical framework of geoeconomics put forth by Edward Luttwak and refined by Blackwill & Harris. Understanding the trajectory of Chinese and Russian foreign aid, trade and investment structures historically and contemporarily allows for a clear understanding of both nations' approach as neither actor is a member of the OECD and as such does not adhere to rigid definitions of what constitutes as foreign aid or other. The Central Asian Republics of Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan and Uzbekistan comprise a geostrategic region, with each individual state endowed with tremendous resource potential that remain in global demand. As China's domestic demand of energy surpasses its supply, it will seek new outlets to further its national interests. The potential...Tato práce se zabývá zkoumáním zahraničních investičních aktivit v Číně, obchodu a vládou sponzorovaných investičních aktivit ve střední Asii od roku 2001 do roku 2014, a pokouší se nalézt odpověď na otázku, zda v důsledku toho nastaly nějaké důsledky pro čínsko-ruské vztahy. Vzhledem k tomu, že Čína pokračovala v trvalém hospodářském růstu, její výdaje na rozvojové projekty se na mezinárodní úrovni začaly zvyšovat. Tato práce se pokouší analyzovat velikost a rozsah finančních toků z Číny do Střední Asie, aby zjistila, zda ovlivnila čínsko-ruské vztahy s využitím teoretického rámce geoekonomie, který předložil Edward Luttwak a zpřesnil Blackwill & Harris. Pro pochopení čínské a ruské zahraniční pomoci, je třeba věnovat se jejich obchodním a investičním strukturám jak v historii, tak i v současnosti, protože ani jeden z nich není členem OECD a jako takový se neřídí přísnými definicemi toho, co přesně představuje zahraniční pomoc. Středoasijské republiky Kazachstánu, Kyrgyzstánu, Tádžikistánu, Turkmenistánu a Uzbekistánu tvoří geo-strategický region, kde každý jednotlivý stát disponuje obrovským zdrojovým potenciálem, o nějž jeví zájem celý svět. Vzhledem k tomu, že domácí poptávka Číny po energii překračuje její produkční schopnosti, vyžadují její národní zájmy přístup k novým zdrojům. Potenciální...Department of Political ScienceKatedra politologieFaculty of Social SciencesFakulta sociálních vě

Chinese Foreign Aid and Investment in Central Asia: Implications on Sino-Russian Relations from a Geopolitical Perspective

This thesis examines China's foreign aid, trade and government-sponsored investment activities in Central Asia from 2001 to 2014, asking and answering the question if any implications on Sino-Russian relations occurred as a result. As China continued to experience sustained economic growth, its development disbursements internationally began to expand as well. This work attempts to analyze the size and scope of these disbursements from China into Central Asia to see if it has impacted Sino-Russian relations utilizing the theoretical framework of geoeconomics put forth by Edward Luttwak and refined by Blackwill & Harris. Understanding the trajectory of Chinese and Russian foreign aid, trade and investment structures historically and contemporarily allows for a clear understanding of both nations' approach as neither actor is a member of the OECD and as such does not adhere to rigid definitions of what constitutes as foreign aid or other. The Central Asian Republics of Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan and Uzbekistan comprise a geostrategic region, with each individual state endowed with tremendous resource potential that remain in global demand. As China's domestic demand of energy surpasses its supply, it will seek new outlets to further its national interests. The potential..

Chinese Foreign Aid and Investment in Central Asia: Implications on Sino-Russian Relations from a Geopolitical Perspective

This thesis examines China's foreign aid, trade and government-sponsored investment activities in Central Asia from 2001 to 2014, asking and answering the question if any implications on Sino-Russian relations occurred as a result. As China continued to experience sustained economic growth, its development disbursements internationally began to expand as well. This work attempts to analyze the size and scope of these disbursements from China into Central Asia to see if it has impacted Sino-Russian relations utilizing the theoretical framework of geoeconomics put forth by Edward Luttwak and refined by Blackwill & Harris. Understanding the trajectory of Chinese and Russian foreign aid, trade and investment structures historically and contemporarily allows for a clear understanding of both nations' approach as neither actor is a member of the OECD and as such does not adhere to rigid definitions of what constitutes as foreign aid or other. The Central Asian Republics of Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan and Uzbekistan comprise a geostrategic region, with each individual state endowed with tremendous resource potential that remain in global demand. As China's domestic demand of energy surpasses its supply, it will seek new outlets to further its national interests. The potential..

MODIFICATION AND INCORPORATION OF C(sp3)-RICH FRAGMENTS WITH PHOTOREDOX CATALYSIS

Chemical synthesis is central to numerous fields of scientific inquiry, providing the fundamental building blocks and tools for research in not only chemistry, but biology, physics, and medicine, among others. Consequently, the discovery and development of new synthetically useful reactions can have an outsized impact on numerous fields. Photoredox catalysis has transformed the field of organic synthesis over the last 15 years by enabling a plethora of new transformations that occur under mild photoirradiation conditions. Through the ability of excited-state photocatalysts to perform electron, atom, or energy transfer with simple organic molecules and transition metal catalysts, highly reactive open-shell intermediates can be generated and subsequently used in a broad range of reactions. Notably, the unique properties of radicals allow for their use in transformations similar to those observed in two-electron reactions or as participants in fundamental steps and reactions that have no analog in closed-shell reactivity. The work described herein employs radical intermediates as key components of reactions that would be challenging or impossible to accomplish with traditional closed-shell reactivity. Chapter 2 discusses a contrathermodynamic epimerization reaction able to generate thermodynamically less-stable cis-configured cyclic diols from their more stable trans counterparts using iterative HAT to interconvert between stereoisomers and a simple boronic acid additive to transiently invert the thermodynamic properties of the two isomers. In Chapter 3, a novel photoredox/nickel cocatalyzed annulation reaction sequence is described that uses two sequential radical couplings in the same reaction vessel to construct highly pharmaceutically-relevant semisaturated fused heterocyclic systems. Chapter 4 describes efforts towards the direct trifluoromethylation of aromatic N–H bonds using a merger of photoredox and copper catalysis to promote an otherwise highly-challenging reductive elimination step