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Pyruvate formate-lyase (acetyl-CoA:formate C-acetyltransferase, EC 2.3.1.54) from anaerobic Escherichia coli cells converts pyruvate to acetyl-CoA and formate by a unique homolytic mechanism that involves a free radical harbored in the protein structure. By EPR spectroscopy of selectively 13C-labeled enzyme, the radical (g = 2.0037) has been assigned to(More)
The first-derivative EPR spectrum of the active form of Escherichia coli pyruvate formate-lyase shows an asymmetric doublet with partially resolved hyperfine splittings (g = 2.0037). Isotope substitution studies demonstrated couplings of a carbon-centered unpaired electron to a solvent-exchangeable proton (a = 1.5 mT) and to further hydrogen nuclei (a =(More)
Pyruvate formate-lyase (formate acetyltransferase; EC 2.3.1.54) of Escherichia coli cells is post-translationally interconverted between inactive and active forms. Conversion of the inactive to the active form is catalyzed by an Fe2+-dependent activating enzyme and requires adenosylmethionine and dihydroflavodoxin. This process is shown here to introduce a(More)
The large zero-field splitting of rigid biradicals makes them important candidates for spin probes of phospholipid membranes. Here we develop an electron spin resonance line-shape model for such probes on the basis of the stochastic Liouville equation. Particular emphasis is given to the slow-diffusional regime, characteristic of bilayers in the gel phase.(More)
An extraordinary plan of official control was carried out in 2008 in Campania (Italy) with the aim to monitor polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (dl-PCBs) levels in buffalo milk and to detect the contaminated farms, most of which are located in Caserta province. For these companies has(More)
The purpose of this study was to identify firstly the extent of contamination both of the aquatic biota and of sediments and secondly any regional differences in the concentrations of these compounds. In 1996, polychlorinated biphenyls (PCBs, including their coplanar congeners) were measured in 58 eel and 50 sediment samples. Furthermore, the veterinary(More)
As a marine mammal species that inhabits shallow nearshore waters, humpback dolphins are likely exposed to a wide range of pollutants from adjacent land-based activities. Increased mortality rates of Australian humpback dolphins (Sousa sahulensis) in waters off a major urbanised centre triggered investigations into the threats to these species, including(More)