The Desulfovibrio gigas aldehyde oxidoreductase contains molybdenum bound to a pterin cofactor and [2Fe-2S] centers. The enzyme was characterized by SDS/PAGE, gel-filtration and analytical ultracentrifugation experiments. It was crystallized at 4 degrees C, pH 7.2, using isopropanol and MgCl2 as precipitants. The crystals diffract beyond 0.3-nm (3.0-A) resolution and belong to space group P6(1)22 or its enantiomorph, with cell dimensions a = b = 14.45 nm and c = 16.32 nm. There is one subunit/asymmetric unit which gives a packing density of 2.5 x 10(-3) nm3/Da (2.5 A3/Da), consistent with the experimental crystal density, rho = 1.14 g/cm3. One dimer (approximately 2 x 100 kDa) is located on a crystallographic twofold axis.

In the last two decades (70 and 80) there took place an intensive controversy in the field of Industrial and Work Sociology. There the topic of the study object of this scientific discipline is again discussed. This controversy, however, has a relatively different sense in comparison with the one that existed in early 60ies. The more recent one followed the increasing number of possibilities of electronical equipment for data processing at the same time its price is decreasing. In this article we try to give knowledge of the main elements that take part in such debate. It is also important to present the international character of the research developed in association with this discussion. It evolves a plurality of research teams that present, compare and synthesize the results of empirical studies that are applied for a wide variety of countries.

In the last two decades (70 and 80) there took place an intensive controversy in the field of Industrial and Work Sociology. There the topic of the study object of this scientific discipline is again discussed. This controversy, however, has a relatively different sense in comparison with the one that existed in early 60ies. The more recent one followed the increasing number of possibilities of electronical equipment for data processing at the same time its price is decreasing. In this article we try to give knowledge of the main elements that take part in such debate. It is also important to present the international character of the research developed in association with this discussion. It evolves a plurality of research teams that present, compare and synthesize the results of empirical studies that are applied for a wide variety of countries.

A novel liquid-crystalline polymer, the toluene-4-sulphonyl urethane of hydroxypropylcellulose (TSUHPC), was prepared through chemical modification of hydroxypropylcellulose (HPC) of Mw = 60000 g mol−1. The resulting polymer was characterized by infrared spectroscopy, differential scanning calorimetry (DSC) and polarizing microscopy. It was found that thermotropic liquid crystal phases are formed between about 60°C and 110°C. Concentrated solutions of TSUHPC in acetone and N,N-dimethylacetamide exhibit cholesteric behaviour, at room temperature. When approaching the lyotropic mesophase to solid transition, either by cooling or by solvent evaporation, very interesting arborescent structures of a seemingly fractal nature may be observed, depending on the kinetics of the transition. A banded texture can be observed when the polymer is sheared near the transition to the isotropic phase.

The design of jobs is defined and its different implications. These aspects must be taken into consideration when applied to new automated systems, once it can occur workers in-adaptations to certain type of activity and tasks. Other concepts that emerge from this are the mental workload, stress, work accidents, shift work, or the physical environment that can reveal to become determinant in the process of job design. That means also the organizational design. In this sense, the manufacturing, organizational and individual dimensions, are the most meaningful in the mentioned process of organizational design. Are analyzed different application cases of robotized systems and their social effects, mostly those that are related to the dimensions of working conditions. Are particularly analyzed the new risk situations that occur with the use of robotic systems. One concludes on the need to take into consideration qualitative variables in the definition and design of robotic cells, jobs and production systems. This consideration influences directly in the labor productivity, in such way that the development of these methodologies of analysis can be considered as integrating the processes of technological innovation in manufacturing.

Cytochrome c peroxidase from Paracoccus denitrificans LMD 52.44 was recently identified. The enzyme contains two c-type haems: one is reducible physiologically by cytochrome c550 from the same organism or non-physiologically by ascorbate (high-potential haem) and the other by dithionite (low-potential haem). The enzymatically active form of the peroxidase is the half-reduced enzyme state, in which the high-potential haem is in the iron(II) state and the low-potential haem is in the iron(III) state. It was found that the two haems interact and that the enzyme binds calcium ions near the haem sites which are necessary to promote its activation. In the oxidized form, the high-potential haem is in a high-spin and the low-potential haem is in a low-spin state. The half-reduction of the enzyme with ascorbate-diaminodurol changes the high-potential haem (high-spin) into a low-spin state and the low-potential haem converts from a low- into a high-spin state. This high-spin conversion of the low-potential haem is induced by the presence of calcium ions. These processes of reduction and spin state change can be easily resolved in time by removing the calcium from the enzyme using EDTA, facilitating the observation of the intermediate form by NMR.

1D and 2D 1H NMR studies are reported on the oxidized and reduced [4Fe-4S] cluster of Desulfovibrio gigas ferredoxin I (Fdl). Several low-field contact shifted resonances (fast relaxing) are assigned to β-CH2 and α-CH coordinated cysteinyl residues. NOESY patterns (supported by 1D NOE experiments) resolves four pairs of geminal β-CH2 protons at low-field. The cluster ligands are assigned non-specifically to Cys8, Cys11, Cys14 and Cys50, based on the X-ray structural analysis available for the oligomeric form, FdII, that contains a single [3Fe-4S] cluster. It was indicated in this case that Cys11 is not bound to the trinuclear cluster but is tilted towards the solvent. The presence of four pairs of geminal β-CH2 protons for FdI unambiguously proves the occupancy of the fourth site of the [3Fe-4S] complex and implies the coordination of the Cys11 at the cluster. Analysis of the oxidized form of FdII, using the same methodology as described for FdI, supports the presence of three cysteinyl ligands in the [3Fe-4S] core. Further, the combined use of the X-ray coordinates enables the specific assignment of the three cysteinyl ligands of the cluster, extending a previous assignment of Cys50. In addition, very broad resonances were detected for the reduced form of FdII in the low-field region around 200 ppm and in the high field region around −80 ppm.

The design of jobs is defined and its different implications. These aspects must be taken into consideration when applied to new automated systems, once it can occur workers in-adaptations to certain type of activity and tasks. Other concepts that emerge from this are the mental workload, stress, work accidents, shift work, or the physical environment that can reveal to become determinant in the process of job design. That means also the organizational design. In this sense, the manufacturing, organizational and individual dimensions, are the most meaningful in the mentioned process of organizational design. Are analyzed different application cases of robotized systems and their social effects, mostly those that are related to the dimensions of working conditions. Are particularly analyzed the new risk situations that occur with the use of robotic systems. One concludes on the need to take into consideration qualitative variables in the definition and design of robotic cells, jobs and production systems. This consideration influences directly in the labor productivity, in such way that the development of these methodologies of analysis can be considered as integrating the processes of technological innovation in manufacturing.

On photolysis of solutions of azulene and uranyl nitrate in alcohols, a dark, amorphous precipitate is formed. Various analytical techniques show that this is a mixture of a uranium salt and an organic component, suggested to be polyazulene. The effects of various parameters on the yield of the product have been studied and it is found that oxygen facilitates the reaction. Electron spin resonance studies show that the product is paramagnetic, in agreement with the established ease of oxidation of polyazulene, and suggest that it is formed via electron transfer from azulene to excited uranyl ion, followed by successive dimerizations and deprotonations of radical cation intermediates.

A soluble [NiFe] hydrogenase has been partially purified from the obligate thermophilic sulfate-reducing bacterium Thermodesulfobacterium mobile. A 17% purification yield was obtained after four chromatographic steps and the hydrogenase presents a purity index (A398 nm/A277 nm) equal to 0.21. This protein appears to be 75% pure on SDS-gel electrophoresis showing two major bands of molecular mass around 55 and 15 kDa. This hydrogenase contains 0.6-0.7 nickel atom and 7-8 iron atoms per mole of enzyme and has a specific activity of 783 in the hydrogen uptake reaction, of 231 in the hydrogen production assay and of 84 in the deuterium-proton exchange reaction. The H2/HD ratio is lower than one in the D2-H+ exchange reaction. The enzyme is very sensitive to NO, relatively little inhibited by CO but unaffected by NO2-. The EPR spectrum of the native hydrogenase shows the presence of a [3Fe-4S] oxidized cluster and of a Ni(III) species.

A novel iron-sulfur protein was purified from the extract of Desulfovibrio desulfuricans (ATCC 27774) to homogeneity as judged by polyacrylamide gel electrophoresis. The purified protein is a monomer of 57 kDa molecular mass. It contains comparable amounts of iron and inorganic labile sulfur atoms and exhibits an optical spectrum typical of iron-sulfur proteins with maxima at 400, 305, and 280 nm. Mossbauer data of the as-isolated protein show two spectral components, a paramagnetic and a diamagnetic, of equal intensity. Detailed analysis of the paramagnetic component reveals six distinct antiferromagnetically coupled iron sites, providing direct spectroscopic evidence for the presence of a 6Fe cluster in this newly purified protein. One of the iron sites exhibits parameters (delta EQ = 2.67 +/- 0.03 mm/s and delta = 1.09 +/- 0.02 mm/s at 140 K) typical for high spin ferrous ion; the observed large isomer shift indicates an iron environment that is distinct from the tetrahedral sulfur coordination commonly observed for the iron atoms in iron-sulfur clusters and is consistent with a penta- or hexacoordination containing N and/or O ligands. The other five iron sites are most probably high spin ferric. Three of them show parameters characteristic for tetrahedral sulfur coordination. In correlation with the EPR spectrum of the as-purified protein which shows a resonance signal at g = 15.3 and a group of signals between g = 9.8 and 5.4, this 6Fe cluster is assigned to an unusual spin state of 9/2 with zero field splitting parameters D = -1.3 cm-1 and E/D = 0.062. Other EPR signals attributable to minor impurities are also observed at the g = 4.3 and 2.0 regions. The diamagnetic Mossbauer component represents a second iron cluster, which, upon reduction with dithionite, displays an intense S = 1/2 EPR signal with g values at 2.00, 1.83, and 1.31. In addition, an EPR signal of the S = 3/2 type is also observed for the dithionite-reduced protein.

Mossbauer spectroscopy was used to study the tetraheme cytochrome c3 from Desulfovibrio baculatus (DSM 1743). Samples with different degrees of reduction were prepared using a redoxtitration technique. In the reduced cytochrome c3, all four hemes are reduced and exhibit diamagnetic Mossbauer spectra typical for low-spin ferrous hemes (S = 0). In the oxidized protein, the hemes are low-spin ferric (S = 1/2) and exhibit overlapping magnetic Mossbauer spectra. A method of differential spectroscopy was applied to deconvolute the four overlapping heme spectra and a crystal-field model was used for data analysis. Characteristic Mossbauer spectral components for each heme group are obtained. Hyperfine and crystal-field parameters for all four hemes are determined from these deconvoluted spectra.

The Desulfovibrio gigas aldehyde-oxido-reductase contains molybdenum and iron-sulfur clusters. Mossbauer spectroscopy was used to characterize the iron-sulfur clusters. Spectra of the enzyme in its oxidized, partially reduced and benzaldehyde-reacted states were recorded at different temperatures and applied magnetic fields. All the iron atoms in D. gigas aldehyde oxido-reductase are organized as [2Fe-2S] clusters. In the oxidized enzyme, the clusters are diamagnetic and exhibit a single quadrupole doublet with parameters (delta EQ = 0.62 +/- 0.02 mm/s and delta = 0.27 +/- 0.01 mm/s) typical for the [2Fe-2S]2+ state. Mossbauer spectra of the reduced clusters also show the characteristics of a [2Fe-2S]1+ cluster and can be explained by a spin-coupling model proposed for the [2Fe-2S] cluster where a high-spin ferrous ion (S = 2) is antiferromagnetically coupled to a high-spin ferric ion (S = 5/2) to form a S = 1/2 system. Two ferrous sites with different delta EQ values (3.42 mm/s and 2.93 mm/s at 85 K) are observed for the reduced enzyme, indicating the presence of two types of [2Fe-2S] clusters in the D. gigas enzyme. Taking this observation together with the re-evaluated value of iron content (3.5 +/- 0.1 Fe/molecule), it is concluded that, similar to other Mo-hydroxylases, the D. gigas aldehyde oxido-reductase also contains two spectroscopically distinguishable [2Fe-2S] clusters.

The magnetic properties of the nickel(II) site in active Desulfovibrio baculatus (DSM 1743) [NiFeSe] hydrogenase have been measured using the multifield saturation magnetization technique. The periplasmic [NiFeSe] hydrogenase was isolated from bacteria grown in excess selenium in the presence of 57Fe. Saturation magnetization data were collected at three fixed fields (1.375, 2.75, 5.5 tesla) over the temperature range from 2 to 100 K. Mossbauer and EPR spectroscopies were used to characterize the magnetic state of the two [4Fe-4S] clusters of the enzyme and to quantitate the small amounts of iron impurities present in the sample. The nickel(II) site was found to be diamagnetic (low spin, S = 0). In combination with recent results from extended x-ray absorption fine structure studies, this magnetic state indicates that the nickel(II) site of active D. baculatus [NiFeSe] hydrogenase is five-coordinate.

The effects of polyammonium macrocycles on the spectroscopic and photochemical properties of the Co(EDTA)- . I- ion-pair have been investigated. The addition of a macrocycle to aqueous solutions containing Co(EDTA)- and I- causes an increase of the absorbance in the region of the ion-pair charge-transfer band, as well as an increase of the quantum yield for the intramolecular photooxidation reduction of the ion-pair. Both these effects are mainly, if not only, due to an increase of the association constant between Co(EDTA)- and I-, caused by the positive charge of the macrocycle bound to the complex. On the contrary no change was observed on the intrinsic photoreactivity of the excited ion-pair. This last result is discussed in comparison with the effects already observed on the ligand photodissociation of MC excited states of Co(III) cyanide complexes.