Pro region C-terminus:protease active site interactions are critical in catalyzing the folding of alpha-lytic protease

alpha-Lytic protease is encoded with a large (166 amino acid) N-terminal pro region that is required transiently both in vivo and in vitro for the correct folding of the protease domain [Silen, J. L. , and Agard, D. A. (1989) Nature 341, 462-464; Baker, D., et al. (1992) Nature 356, 263-265]. The pro region also acts as a potent inhibitor of the mature enzyme [Baker, D., et al. (1992) Proteins: Struct.,Funct., Genet. 12, 339-344]. This inhibition is mediated through direct steric occlusion of the active site by the C-terminal residues of the pro region [Sohl, J. L., et al. (1997) Biochemistry 36, 3894-3904]. Through mutagenesis and structure-function analyses we have begun to investigate the mechanism by which the pro region acts as a single turnover catalyst to facilitate folding of the mature protease. Of central interest has been mapping the interface between the pro region and the protease and identifying interactions critical for stabilizing the rate-limiting folding transition state. Progressive C-terminal deletions of the pro region were found to have drastic effects on the rate at which the pro region folds the protease but surprisingly little effect on inhibition of protease activity. The observed kinetic data strongly support a model in which the detailed interactions between the pro region C-terminus and the protease are remarkably similar to those of known substrate/inhibitor complexes. Further, mutation of two protease residues near the active site have significant effects on stabilization of the folding transition state (kcat) or in binding to the folding intermediate (KM). Our results suggest a model for the alpha-lytic protease pro region-mediated folding reaction that may be generally applicable to other pro region-dependent folding reactions.     

Pyrometric temperature and size measurements of chalcopyrite particles during flash oxidation in a laminar flow reactor

A fast two-color pyrometer has been constructed and applied to simultaneous temperature and size measurements of individual chalcopyrite particles (CuFeS₂) during flash oxidation in a laminar flow reactor. The influence of different oxygen concentrations (0, 10, 20, 50, and 75 vol pct), gas temperatures (1073 and 1273 K), particle size fractions (53 to 74 μm and 74 to 150 μm), and reaction times (up to 0.17 seconds) on chalcopyrite particle temperature and size distributions was studied. The particle reaction rates were characterized by the sulfur mass in the solid reaction product. Particle temperatures ranged from the ambient gas temperature up to 2700 K. A strong correlation between the oxygen concentration and the median particle temperature was observed.     

Тhe Еffectiveness of Metal and Metalloid Sorption from Mining Influenced Waters by Natural and Modified Peat

This study investigated the sorption behaviour of natural (N peat) and HCl-acid-modified peat (HCl peat) for contaminants in water collected at a mine site in northern Finland. Batch sorption experiments were conducted at room temperature and at 5 °C. Characterization of the sorbents by FTIR and XPS revealed no substantial change in the peat’s functional groups due to the acid treatment. Generally, the N peat was a more efficient sorbent for the mine water, although the HCl peat exhibited better nickel uptake capacity (21 mg Ni/g) than the N peat (16 mg Ni/g) from synthetic water. This is attributed to the lower equilibrium pH in samples treated with the HCl peat as well as the water’s different chemical composition. At room temperature, the N peat removed As(V) (80%) and Ni (85%) at low dosage (1–2 g/L), whereas the HCl peat presented good removal of As(V) (80%) at low dosage (1 g/L) but did not achieve satisfactory removal of Ni, even at a higher dosage (4 g/L). The performance of both sorbents was significantly affected by contact time. Ni removal by N peat increased substantially with contact time whereas removals achieved by HCl peat increased slightly up to 60 min, but decreased significantly at 24 h. Unlike with HCl peat, the N peat was less efficient in the experiments conducted at 5 °C. Overall, for both sorbents, As(V) and Ni were the most efficiently removed contaminants from the mine water. HCl peat had slightly better settling properties, however, both products settled poorly, thus rendering the studied mixing and settling system unsuitable for the proposed application. Nevertheless, both peat products, and especially the N peat, exhibited high contaminant removal potential and could represent a cost-effective and sustainable option for mine water treatment.     

Exposure to environmental tobacco smoke at work, at home, and during leisure time: a cross-sectional population sample

Environmental tobacco smoke (ETS) is among the most common environmental health risks, with a striking and immediate biological response and increased disease risk. Exposure studies have looked mostly at worksite or home exposures, whereas total exposure levels at the population level are rarely reported. This study examined ETS exposure at work, at home, and during leisure time in a cross-sectional population sample of working-age adults. Our aim was to monitor changes in ETS exposure from 1992 to 2002. More detailed information on duration of exposure, distribution of exposure sites, and patterns of exposure was obtained in 2002. Data were based on Finland's national population chronic disease risk-factor surveys (conducted every 5 years). Total sample size varied from 8,000 to 13,500. The survey includes a self-administered questionnaire about ETS exposure at different sites. The proportion of nonsmoking persons exposed to ETS declined throughout the study period among both men and women. In 2002, 5.9% of male and 3.6% of female nonsmokers were exposed to ETS 1 hour or more per day, whereas 5.8% of men and 1.7% women were exposed less than 1 hour daily. Worksite exposure was more common among younger age groups of both sexes, but nonsmoking women in older age groups received more exposure at home than at worksites. Policy developments on ETS should aim to protect the whole population from ETS in all environments given that health risks from ETS often persist at home and in leisure environments. Total exposure levels should be studied to assess the health impacts of ETS.     

Characterizing Mold Problem Buildings – Concentrations And Flora Of Viable Fungi

The purpose of this study was to characterize mold problem buildings by determining concentrations and flora of viable fungi. The composition and concentrations of fungal flora in mold problem (n = 9) and reference buildings (n = 9) were determined by means of four different sampling methods: six-stage impactor (Andersen sampler), sedimentation plate, surface and house dust samples. Samples were taken in the fall and in the winter, and the concentrations and flora in mold problem buildings were compared with those of matched reference buildings. The differences between mold problem and reference buildings were most clearly seen with the impactor samples. The total concentrations of airborne fungi were higher in moldy buildings. In addition, the concentrations of the genera Aspergillus and Oidiodendron in the fall and the concentrations of Aspergillus and Penicillium in the winter were higher in mold problem than in reference buildings. In the winter, certain fungal genera (Stachybotrys, Acremonium, Oedocephalum and Botryosporium) were detected only in the problem buildings in impactor samples. These results indicate that there may be an unusual composition of fungal flora in mold problem buildings. The results of the sedimentation plate samples showed a trend similar to that of impactor samples in the winter. In addition, the results of surface samples supported the data on the fungal flora in the winter-time air samples. The house dust samples did not reveal any differences between mold problem and matched reference buildings.     

Emissions trading and investment decisions in the power sector—a case study in Finland

Organizations, which consider investment in or divestment of power production licences/capacity within the European Community, are exposed to the impacts of the European Union Emission allowance Trading Scheme (EU ETS). In this paper, the consequences of the EU ETS on investment decisions are explored in a country-specific setting in Finland. First, we review the general mechanisms through which the EU ETS influences size, timing and cashflows of an investment. Next, we discuss the projected changes in Finnish power producers’ investment environment and examine the financial impacts due to the EU ETS on a case investment decision, a hypothetical condensing power plant (250 MW_e). The standard discounted cash flow (DCF) analysis is extended to take into account the value of two real options: the option to wait and the option to alter operating scale. In a quantitative investment appraisal, the impact of emissions trading not only depends on the expected level of allowance prices, but also on their volatility and correlation with electricity and fuel prices. The case study shows that the uncertainty regarding the allocation of emission allowances is critical in a quantitative investment appraisal of fossil fuel-fired power plants.     

Comparison of direct and alternating current vacuum ultraviolet lamps in atmospheric pressure photoionization

A direct current induced vacuum ultraviolet (dc-VUV) krypton discharge lamp and an alternating current, radio frequency (rf) induced VUV lamp that are essentially similar to lamps in commercial atmospheric pressure photoionization (APPI) ion sources were compared. The emission distributions along the diameter of the lamp exit window were measured, and they showed that the beam of the rf lamp is much wider than that of the dc lamp. Thus, the rf lamp has larger efficient ionization area, and it also emits more photons than the dc lamp. The ionization efficiencies of the lamps were compared using identical spray geometries with both lamps in microchip APPI mass spectrometry (μAPPI-MS) and desorption atmospheric pressure photoionization-mass spectrometry (DAPPI-MS). A comprehensive view on the ionization was gained by studying six different μAPPI solvent compositions, five DAPPI spray solvents, and completely solvent-free DAPPI. The observed reactant ions for each solvent composition were very similar with both lamps except for toluene, which showed a higher amount of solvent originating oxidation products with the rf lamp than with the dc lamp in μAPPI. Moreover, the same analyte ions were detected with both lamps, and thus, the ionization mechanisms with both lamps are similar. The rf lamp showed a higher ionization efficiency than the dc lamp in all experiments. The difference between the lamp ionization efficiencies was greatest when high ionization energy (IE) solvent compositions (IEs above 10 eV), i.e., hexane, methanol, and methanol/water, (1:1 v:v) were used. The higher ionization efficiency of the rf lamp is likely due to the larger area of high intensity light emission, and the resulting larger efficient ionization area and higher amount of photons emitted. These result in higher solvent reactant ion production, which in turn enables more efficient analyte ion production.     

Comparison of mold concentrations quantified by MSQPCR in indoor and outdoor air sampled simultaneously

Mold specific quantitative PCR (MSQPCR) was used to measure the concentrations of the 36 mold species in indoor and outdoor air samples that were taken simultaneously for 48 h in and around 17 homes in Cincinnati, Ohio. The total spore concentrations of 353 per m(3) of indoor air and 827 per m(3) of outdoor air samples were significantly different (por=0.5). These results suggest that interpretation of the meaning of short-term (<48 h) mold measurements in indoor and outdoor air samples must be made with caution.