Mechanistic Importance of Redox Potentials and Conformational Flexibility in Electron-Transferring Flavoproteins

The mitochondrial matrix flavoproteins electron transfer flavoprotein (ETF) and electron transfer flavoprotein-ubiquinone oxidoreductase (ETF-QO) are responsible for linking fatty acid β-oxidation with the main mitochondrial respiratory chain. Electrons derived from flavoprotein dehydrogenases are transferred sequentially through ETF and ETF-QO to ubiquinone and then into the respiratory chain via complex III. In this study, the effects of changes in ETF-QO redox potentials on its activity and the conformational flexibility of ETF were investigated. ETF-QO contains one [4Fe-4S]2+,1+ and one flavin adenine dinucleotide (FAD). In the porcine protein, threonine 367 is hydrogen bonded to N1 and O2 of the flavin ring of the FAD. The analogous site in Rhodobacter sphaeroides ETF-QO is asparagine 338. Mutations N338T and N338A were introduced into the R. sphaeroides protein by site-directed mutagenesis to determine the impact of hydrogen bonding at this site on redox potentials and activity. FAD redox potentials were measured by potentiometric titration probed by electron paramagnetic resonance (EPR) spectroscopy. The N338T and N338A mutations lowered the midpoint potentials, which resulted in a decrease in the quinone reductase activity and negligible impact on disproportionation of ETF1e- catalyzed by ETF-QO. These observations indicate that the FAD is involved in electron transfer to ubiquinone, but not in electron transfer from ETF to ETF-QO. Therefore it is proposed that the iron-sulfur cluster is the immediate acceptor from ETF. It has been proposed that the αII domain of ETF is mobile, allowing promiscuous interactions with structurally different partners. Double electron-electron resonance (DEER) was used to measure the distance between spin labels at various sites and an enzymatically reduced FAD cofactor in Paracoccus denitrificans ETF. Two or three interspin distance distributions were observed for spin-labels in the αI (A43C) and βIII (A111C) domains, but only one is observed for a label in the βII (A210C) domain. This suggests that the αII domain adopts several stable conformations which may correspond to a closed/inactive conformation and an open/active conformation. An additional mutation, E162A, was introduced to increase the mobility of the αII domain. The E162A mutation doubled the activity compared to wild-type and caused the distance distributions to become wider. The DEER method has the potential to characterize conformational changes in ETF that occur when it interacts with various redox partners.

Ukraine, Russia and the need for more flexibility in EU foreign policy-making. CEPS Policy Brief No. 320, 25 July 2014

After the illegal annexation of Crimea and Russia’s indirect responsibility for the downing of Malaysia Airlines flight MH17 in eastern Ukraine, Steven Blockmans asks what it will take before the EU is able to confront a conflict on its borders and prove to both its own citizens and third countries that it has a meaningful role to play in foreign policy. With numerous competing national interests and some member states unwilling to pay different prices for collective action, any sector-wide EU sanctions are likely to lack serious bite. In an effort to paper over the cracks, the author makes a number of recommendations for policy-makers.

Agricultural Labour Market Flexibility in the EU and Candidate Countries. Factor Markets Working Document No. 49, June 2013

Factor markets that function well are a crucial condition for the competitiveness and growth of agriculture. Institutions and regulation may give rise to agricultural labour market heterogeneity, which could have important effects on the functioning of the labour market and other agricultural factor markets in EU member states. This paper first defines the institutional framework for the labour market, and then presents a brief literature review of previous studies of labour market institutional frameworks. Based on the literature, a survey to characterise agricultural labour markets was undertaken, which was implemented for a selection of EU27 and EU candidate countries, with responses based on expert opinion. The survey data were then used to construct indices of labour market flexibility/rigidity for the countries examined. These indices were used to make inter-country labour market comparisons and to draw inferences about the institutions and functioning of the agricultural labour market.

Taylor's sacred minstrel, or, American church music book : a new collection of psalm and hymn tunes adapted to the various metres now in use : together with anthems, sentences, chants and other pieces : for the use of choirs, congregations, singing schools, musical societies, social sacred music circles, and private devotion ... /

Mode of access: Internet.

Vehicles-in-use sub-limit maneuvers. Volume I: executive summary. Final report.

National Highway Traffic Safety Administration, Vehicle Engineering Research Division, Washington, D.C.

Vehicles-in-use sub-limit maneuvers. Volume II: multi-vehicle test validation. Final report.

National Highway Traffic Safety Administration, Vehicle Engineering Research Division, Washington, D.C.

Vehicles-in-use sub-limit maneuvers. Volume III: effects of vehicle-in-use spring sag on vehicle handling and braking. Final report.

National Highway Traffic Safety Administration, Vehicle Engineering Research Division, Washington, D.C.

Seals and other devices in use in the Government Printing Office.

Mode of access: Internet.

Existing and probable next-decade vehicle-in-use inspection standards and procedures. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

Vehicle-in-use program plan.

Mode of access: Internet.

Development of vehicles-in-use sub-limit maneuvers. Volume II: technical report. Final report.

National Highway Traffic Safety Administration, Crash Avoidance Research Division, Washington, D.C.

Development of vehicles-in-use sub-limit maneuvers. Volume I: summary report. Final report.

National Highway Traffic Safety Administration, Crash Avoidance Research Division, Washington, D.C.