Studies on lipid involvement in the mechanism of energy coupling

The interactions of derivatives of lipoic acid and unsaturated fatty acids with the mitochondrial energy coupling system was investigated. Derivatives of dihydrolipoic acid, oleoyl-S-lipoate and oleoyl phosphate were observed to stimulate ATP synthesis in a number of ATPase preparations derived from bovine heart and other mitochondria. This synthesis was sensitive to various inhibitors of oxidative phosphorylation such as oligomycin, efrapeptin, triorganotin halides and uncoupling agents. A derivative of dihydrolipoic acid also stimulated an energy-linked transhydrogenase reaction in bovine heart SMP. This reaction has features in common with both ATP and respiration-driven transhydrogenase. All these reactions were observed at a low frequency. The reasons for this were investigated as were the precise natures of the compounds stimulating ATP synthesis. No clear answers were obtained to either question, although suggestions were made. The role of ubiquinone in energy coupling was also investigated, using solvent extraction studies and a low molecular weight homologue of ubiquinone, ubiquinone 3. These studies suggest that ubiquinone may have a role in energy coupling reactions other than that expected from its well-know role as a respiratory chain redox carrier, possibly in the control of various ATPase-linked reactions, e.g. ATP synthesis, ATP—Pi exchange, ATP-driven transhydrogenase. The results presented here describing 'dihydrolipoate' driven ATP synthesis (tables 3.1-3.19 & fig.3.2) and oleoyl phosphate driven ATP synthesis and ATP-Pi exchange ( tables 5.3-5.10 & figs.5.1-5.7 ) were most of those obtained showing these reactions over a two year period and represent 'v 1% of the total number of attempts to demonstrate them (see pp 88-89,212-213). The remaining results presented in this thesis are usually representative of 2-6 experiments performed in duplicate

Deliverable, Low-Cost Student Response Systems

This paper describes three deliverable, low-cost student response systems - software tools for providing Instructors with immediate feedback on students. Each of these tools has been and Is being developed at the United States Military Academy for similar purposes. First, the software can be used as a lesson structuring tool. Instructors can tailor their presentations to classes based on the results of their students\u27 lesson preparation the night before. This results in classes that are specifically targeted at those subjects the students had difficulty with. As a result, the instructors can better utilize their class period and the students will find the classroom Instruction more valuable. Second, we have used the software during class to validate that the students understand a particular learning objective before moving on to the next learning objective or to tabulate the class\u27 opinion on a student submission anonymously. Due to the automatic, real-time grading of results, the student response system allows greater control over class presentations by providing relevant feedback to the instructor and the student in real-time. Finally, the student response system can be incorporated into courses taught using hypermedia. As before, the system provides critical feedback to the student and Instructor alike and allows for the tailoring of study sessions and course material respectively

Comparison And Validation Of Modelling Methods For Non-Homogenous Walls Incorporating Vacuum Insulation Panels

As of 2012, space heating accounted for 62% of Canada’s secondary residential energy use, the most significant category by a large margin. New strategies and policies to reduce overall energy consumption, with a focus on reducing space heating energy. Voluntary performances standards have been developed for new homes including R-2000, LEED Canada for Homes and Passive House. These standards add a series of performance criteria, in addition to conventional building code, in an effort to reduce a home’s energy consumption and include a limit on energy and water consumption, and prescribe minimum levels of insulation, ventilation, etc. Generally, extensive modelling, proof of concept and/or builder training are required to obtain the energy efficiency designation. A common method of maintaining a home within the constrained energy budget is to increase the overall air tightness and insulation in the dwelling above conventional construction standards through additional sealing and insulation. The typical industry practice for increasing the insulation value involves simply adding more insulation. However, this practice is not always possible or favorable. For example, adding thickness to the walls will either increase the dwelling’s footprint or reduce the usefulfloor space within the home. As a consequence, many studies are being performed on vacuum insulated panels (VIPs), which offer a high thermal resistance per unit thickness when compared to conventional materials. VIPs consist of a metallic enclosure and a vacuum maintained inside, effectively eliminating the conduction through the center of panel, however a thermal bridge will occur along the edges. There are concerns about whether the fragility and the non-homogenous nature of the panels will cause problems within residential dwellings, as well as how to model VIPs within building assemblies effectively. Currently, there is no method of efficiently modelling the non-homogenous nature of the panels in building applications to meet requirements prescribed in performance standards, hinders the widespread adoption of VIPs. This paper compares two methods of modelling the steady-state heat transfer across a composite, non-homogenous wall assembly containing VIPs validated against measured experimental data. Method 1 is the typical practice used by industry experts and involves creating a thermal model for each unique 2D profile within the wall assembly independently. The effective thermal conductivity (U-value) for the assembly was calculated using weighted averages method based on proportional coverage area of each profile and involves multiplying the U-value by the ratio of profile height to the overall height of the wall. In method 2, a single profile was created based on the wall composition, coverage area, and layout of non-homogenous sections to represent the entire assembly then modelled in THERM. The results of both methods were compared to an empirically calculated thermal resistance based on measured heat flux across five points in a representative assembly under steady-state conditions in a guarded hot box. The feasibility of using either modelling method to find the thermal resistance of wall assemblies incorporating VIPs and if a single representative profile can accurately determine thermal resistance to avoid modelling all profiles included within the wall was examined

The terminal respiratory chain of the methylotrophic bacterium Methylophilus methylotrophus

AbstractCytochrome oxidase o has been isolated from the obligately aerobic, methylotrophic bacterium Methylophilus methylotrophus in the form of a cytochrome cL-o complex. The latter is comprised of cytochrome cL (Mr 21 000) and cytochrome o (Mr 29 000) in a 1–2:1 ratio, possibly in association with one or more minor polypeptides; the complex exhibits a high ascorbate-TMPD oxidase activity which is inhibited non-competitively by cyanide (Ki ≈ 2 μM). In contrast, the oxidation of methanol by whole cells is inhibited uncompetitively by cyanide (Ki≈4 μM), thus indicating the involvement in methanol oxidation of cytochrome oxidase aa3 rather than o

Clusterin is an extracellular chaperone that specifically interacts with slowly aggregating proteins on their off-folding pathway

Clusterin is an extracellular mammalian chaperone protein which inhibits stress-induced precipitation of many different proteins. The conformational state(s) of proteins that interact with clusterin and the stage(s) along the folding and off-folding (precipitation-bound) pathways where this interaction occurs were previously unknown. We investigated this by examining the interactions of clusterin with different structural forms of α-lactalbumin, γ-crystallin and lysozyme. When assessed by ELISA and native gel electrophoresis, clusterin did not bind to various stable, intermediately folded states of α-lactalbumin nor to the native form of this protein, but did bind to and inhibit the slow precipitation of reduced α-lactalbumin. Reduction-induced changes in the conformation of α-lactalbumin, in the absence and presence of clusterin, were monitored by real-time 1H NMR spectroscopy. In the absence of clusterin, an intermediately folded form of α-lactalbumin, with some secondary structure but lacking tertiary structure, aggregated and precipitated. In the presence of clusterin, this form of α-lactalbumin was stabilised in a non-aggregated state, possibly via transient interactions with clusterin prior to complexation. Additional experiments demonstrated that clusterin potently inhibited the slow precipitation, but did not inhibit the rapid precipitation, of lysozyme and γ-crystallin induced by different stresses. These results suggest that clusterin interacts with and stabilises slowly aggregating proteins but is unable to stabilise rapidly aggregating proteins. Collectively, our results suggest that during its chaperone action, clusterin preferentially recognises partly folded protein intermediates that are slowly aggregating whilst venturing along their irreversible off-folding pathway towards a precipitated protein

Structure of the TPR Domain of AIP: Lack of Client Protein Interaction with the C-Terminal alpha-7 Helix of the TPR Domain of AIP Is Sufficient for Pituitary Adenoma Predisposition

PMCID: PMC3534021This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

The Interaction of αB-Crystallin with Mature α-Synuclein Amyloid Fibrils Inhibits Their Elongation

αB-Crystallin is a small heat-shock protein (sHsp) that is colocalized with α-synuclein (αSyn) in Lewy bodies—the pathological hallmarks of Parkinson's disease—and is an inhibitor of αSyn amyloid fibril formation in an ATP-independent manner in vitro. We have investigated the mechanism underlying the inhibitory action of sHsps, and here we establish, by means of a variety of biophysical techniques including immunogold labeling and nuclear magnetic resonance spectroscopy, that αB-crystallin interacts with αSyn, binding along the length of mature amyloid fibrils. By measurement of seeded fibril elongation kinetics, both in solution and on a surface using a quartz crystal microbalance, this binding is shown to strongly inhibit further growth of the fibrils. The binding is also demonstrated to shift the monomer-fibril equilibrium in favor of dissociation. We believe that this mechanism, by which a sHsp interacts with mature amyloid fibrils, could represent an additional and potentially generic means by which at least some chaperones protect against amyloid aggregation and limit the onset of misfolding diseases