Environmental analysis of sunflower production with different forms of mineral nitrogen fertilizers.

Environmental profiles of mineral nitrogen fertilizers were used to evaluate the environmental disturbances related to their use in cultivation systems in Europe. Since the production of mineral fertilizers requires a large amount of energy, the present study of bioenergy systems is relevant in order to achieve crop yields less dependent on fossil fuels and to reduce the environmental impact due to fertilization. In this study, the suitability of the LCA methodology to analyze the environmental impact of sunflower cultivation systems with different forms of mineral nitrogen fertilizers urea and ammonium nitrate was investigated. Effects on climate change were estimated by the use of Ecoinvent 2.2 database default value for soil N2O emission factor (1%) and local emission data (0.8%) of mineral nitrogen applied to soils. LCA analysis showed a higher impact on environmental categories (human health and ecosystem quality) for the system in which urea was used as a nitrogen source. Use of urea fertilizer showed a higher impact on resource consumption due to fossil fuel consumption. Use of mineral nitrogen fertilizers showed a higher environmental burden than other inputs required for sunflower cultivation systems under study. Urea and ammonium nitrate showed, respectively, a 7.8% and 4.9% reduced impact of N2O as greenhouse gas by using direct field data of soil N2O emission factor compared to the default soil emission factor of 2006 IPCC Guidelines. Use of ammonium nitrate as mineral nitrogen fertilizer in sunflower cultivation would have a lower impact on environmental categories considered. Further environmental analysis of available technologies for fertilizer production might be also evaluated in order to reduce the environmental impacts of each fertilizer.

Comparative life cycle assessment study on environmental impact of oil production from micro-algae and terrestrial oilseed crops.

In this study the LCA methodology is applied in order to satisfy two goals: i) to evaluate the hot spots in site-specific production chain of biodiesel from terrestrial and micro-algae feedstock; ii) to compare quantitatively, utilizing primary data, the impacts of the first generation in respect to the third generation bio-fuels. Results show that micro-algae are neither competitive yet with traditional oil crops nor with fossil fuel. The use of renewable technologies as photovoltaics and biogas self production might increase the competitiveness of micro-algae oil. Further investigations are however necessary to optimize their production chain and to increase the added value of co-products.

Coordination behaviour of antithyroid drugs against the Fe(I)(NO)2 group in solution: ESR and FT-NMR study.

The binding sites of some types of antithyroid drugs in the presence of the Fe(I)(NO)2 paramagnetic probe were investigated. Coordination behaviour in solution of different structured ligands was determined by means of ESR parameters and 13C FT-NMR spectra. Selective isotopic substitution with 15NO combined with computer simultation was used to elucidate overlapping ESR patterns. A correlation between chemical structure and antithyroid activity of the pharmacological bases is suggested.

Co-ordination behaviour of nucleic acid bases against the Fe(I)(NO)-2 group in solution. I. Purines: ESR study.

The binding sites of purine bases in the presence of the Fe(I)(NO)-2 group were investigated on the basis of the nuclear hyperfine structure of the electron spin resonance spectra. Selective isotopic substitution with 15-NO was used to clarify co-ordindination. Coupling constants and different types of complexes were determined by means of computer-simulated ESR spectra. Comparison was made with the binding sites of nucleotides and it was concluded that N-7, in the imidazole ring, is the preferred binding site. A structure with two base molecules bonded to the iron atom was proposed. Finally 8-azaguanine, an antitumoral agent, was studied and the special behaviour of this antimetabolite was demonstrated in the biologically-interesting pH values.

ESR parameters for cupric bleomycin in the mobilized state.

The configuration of the copper complex of the glycopeptide bleomycin, CuBlm, is presumed to be pyramidal square planar from a previous X-ray structural determination of a fragment of cupric bleomycin. This study presents evidence for a difference in the ESR parameters for cupric bleomycin in the liquid as opposed to the solid state. A decrease in Aiso for CuBlm in the liquid state can be directly surmised from the low frequency S-band spectrum for which three of the four cupric hyperfine lines are partially resolved. Computer simulated spectra infer that the absolute value of All increases about 100 MHz and the value of Al may change sign for CuBlm in the liquid state. Simulations using a rotational correlation time of about 250 psec. indicate that CuBLM may not be spherical in the liquid phase. The fastest component for anisotropic motion could dominate and account for the well resolved cupric hyperfine structure. Furthermore, it is argued from an analysis of the cupric hyperfine coupling constants that the CuBlm structure opens up at room temperature and that the cupric ion is displaced from the square plane.

Gold complexes of purine and pyrimidine nucleosides.

the reactions of chloroauric acid (HAuCl4) with inosine=ino, guanosine=guo, triacetylinosine=trino, triacetylguanosine=trguo, and cytidine=cyd were studied. Complexes of AU(III) and AU(I) with these nucleosides have been isolated from the reactions at different pH values in aqueous and in methanolic solutions. The Au(I) complexes were obtained by reducing Au(III) with 1-ascorbic acid in aqueous solutions. All the isolated complexes were characterized by elemental analyses, conductivity measurements, IR, 1H nmr, and esr spectra. The Au(III) complexes correspond to the general formulae [Au(nucl)2Cl2]Cl, Au(nucl)Cl3, and Au(nucl-H+Cl2, while the Au(I)complexes are of the au(nucl)2Cl type, where nucl represents the above nucleosides. In the complex with the composition (AucydCl2]2 that was isolated from aqueous solutions, the Au atom is believed to be in the (II) oxidation state. Possible structures for all the isolated complexes based on the experimental data are proposed and discussed.

The effect of binding divalent metal ions on the conformation of human angiotensin-II in solution as probed by nuclear and electron paramagnetic resonance investigations.

The interaction between human angiotensin-II and Mn(II) ions in water solution has been delineated by nmr and esr experiments. A pH-dependent binding interaction with the imidazole moiety of His 6 has been shown, ratifying the suggestion that His 6 is involved in intramolecular structuring within the peptide molecule.

NMR investigation of the copper(II)-carnosine complex in water solution.

The predominant species in water solution of excess carnosine and Cu2+ ions was characterized by measuring 13C and 1H spin-lattice and spin-spin relaxation rates. Four peptide molecules were calculated to be coordinated to the metal through the imidazole nitrogen. Evaluation of ion-proton distances demonstrated that metal complexation does not involve severe changes in conformation of the peptide.

Structural, motional, and kinetic features of the Cu(II)-(L-His)2 complex in aqueous solution.

A careful analysis by 1H and 13C FT-NMR on the Cu(II) (L-histidine)2 complex was carried out which allows delineation of structure and dynamics in solution. A mixture of complexes was shown such that 24% of the Cu(II) (L-histidine)2 complex contains both histidines bound in the histaminelike way, while the remaining 76% contains one L-His molecule bound in the histaminelike way and the other L-His molecule bound in the glycinelike way. The motional correlation time and relevant features of the exchange process were also delineated.

EPR characterization of mono(thiosemicarbazones) copper(II) complexes. Note II.

Copper(II) complexes with thiosemicarbazones have been shown to be more active in cell destruction, in the inhibition of DNA synthesis than the uncomplexed ligand. Several derivatives of thiosemicarbazones and their iron and copper complexes have been studied for their cytotoxicity and inhibiting activity against DNA synthesis. In the present work complexes formed in H2O-DMSO solution between copper(II) and the acetophenone thiosemicarbazone (ATSC) and the o-aminobenzaldehyde thiosemicarbazone (o-NH2TSC) have been studied. EPR studies have been performed at different pH values and metal-to-ligand ratios. The spectra have been recorded at both room (298 K) and low temperatures (120 K). A possible relationship between structure and activity is attempted on the basis of the EPR data.

An electron spin resonance study and antimicrobial activity of copper(II)-phenanthroline complexes.

The antimicrobial activities of some copper(II) binary complexes with unsubstituted and different substituted phenanthroline ligands were investigated. A considerable increase in the biocidal activity of the ligands on being coordinated with the copper(II) ions was observed in terms of their minimum inhibitory concentration (MIC) values. EPR measurements were performed at room and low temperature with the aim of gaining an insight into the structure/activity relationship of these complexes. Subtle differences in the chemical arrangement result in appreciable differences in the antimicrobial activity. Copper(II) complexes with 2,9-dimethyl derivative phenanthrolines were observed to be more active against Staphylococcus aureus and Escherichia coli.

EPR and O2.- scavenger activity: Cu(II)-peptide complexes as superoxide dismutase models.

Several copper(II) complexes with aminoacids and peptides are known to show superoxide dismutase (SOD)-like activity. EPR spectroscopy has proved to be a useful tool for studying the complex equilibria of the copper(II) ion and various ligands of biological importance in solution. In the present work, a variety of copper(II) complexes with di-, tri- and tetra-peptides containing only glycine residues (GG, GGG and GGGG) and others containing a histidyl residue in different positions (HGG, GHG, GGH and GGHG) have been investigated. EPR parameters obtained by extensive use of computer simulation of spectra lead to reliable spin Hamiltonian EPR parameters at both room temperature and in frozen solution. The molecular orbital coefficients computed from the anisotropic EPR data and the d-d electronic energies are used to characterize different arrangements of the complexes. Estimation of the scavenger activity of the complexes due to the particular environment created by the ligands around copper is discussed in the frame of the structure-activity relationship.

Interaction between low-affinity cupric ion and human methemoglobin.

Human hemoglobin has been shown to contain a high- as well as a low-affinity binding site for cupric ion on each of its constitutent beta chains. The copper that is bound to the low-affinity site has been implicated in the selective oxidation of the beta hemes. In the present work a low-affinity binding site for cupric ion has been located within 10 A of the heme iron in human hemoglobin. It is suggested that the proximal histidine is involved in the binding of copper at this site and that it participates in the oxidation of heme iron and reduction of cupric ion.

EPR spin trapping of a radical intermediate in the urate oxidase reaction.

Urate oxidase, or uricase (EC 1.7.3.3), is a peroxisomal enzyme that catalyses the oxidation of uric acid to allantoin. The chemical mechanism of the urate oxidase reaction has not been clearly established, but the involvement of radical intermediates was hypothesised. In this study EPR spectroscopy by spin trapping of radical intermediates has been used in order to demonstrate the eventual presence of radical transient urate species. The oxidation reaction of uric acid by several uricases (Porcine Liver, Bacillus Fastidiosus, Candida Utilitis) was performed in the presence of 5-diethoxyphosphoryl-5-methyl-pyrroline-N-oxide (DEPMPO) as spin trap. DEPMPO was added to reaction mixture and a radical adduct was observed in all cases. Therefore, for the first time, the presence of a radical intermediate in the uricase reaction was experimentally proved.

The cis/trans isomerization of Cu(II)-bis-(glycinato) complex in solution: a computer aided multifrequency EPR and DFT/PCM calculation study.

In this paper the Cu(II)-bis-(glycinato) complex has been analysed in solution by applying a combined approach of multifrequency EPR and DFT/PCM calculations. The accuracy in the determination of magnetic parameters has been reached by the use of a unique simulation program (COSMOS) for the whole range of temperatures analysed and by the error analysis. A change in magnetic parameters was envisaged in the 243-253 K range of temperature, and was interpreted in terms of stabilization, near the freezing point of the solution, of one of the isomers of the complex. A DFT/PCM computational model was crucial in assigning, on the basis of the experimental superhyperfine interaction value, the isomer to the trans form.

Evidence that divalent cations bind to diphtheria toxin: an ESR approach.

We have used electron spin resonance (ESR) techniques to study the binding of divalent cations to diphtheria toxin (DT). Addition of DT to Mn(II) solution at a stoichiometry of 2:1 (DT:Mn) induces a 79% loss in the intensity of the ESR spectrum of Mn(II) suggesting a strong binding of Mn(II) to DT. Inclusion of Ca(II) at a ratio of 1:2:1 (Ca:DT:Mn) in the reaction mixture restores the intensity of the Mn(II) signal to 64%. This indicates that Ca(II) and Mn(II) share same binding site(s) in DT. The results presented in this communication suggest that DT is a Ca(II) binding protein.

Diphtheria toxin induces leakage of acidic liposomes.

Diphtheria toxin (DT) induces the leakage of dipalmitoylphosphatidic acid (DPPA) membranes but not neutral dipalmitoylphosphatidylcholine (DPPC) membranes. Cholesterol incorporated into liposomes enhances the membrane leakage induced by DT in acidic DPPA membranes but not in neutral DPPC membranes. Membrane leakage was determined by assaying the release of TEMPOcholine, a cationic spin probe from the multilamellar vesicles by using electron spin resonance methods. The effect of DT on membrane leakage is noticeable at 3 micrograms/ml concentrations, and reaches a plateau of about 20% leakage at 20 micrograms/ml. This saturation phenomenon led to the postulation that DT binds to the first shell of DPPA membranes and induces the leakage of TEMPOcholine limited to this layer of DPPA multimellar vesicles.