J Biol Inorg Chem (2007) 12 (Suppl 1):S203–S206 DOI 10.1007/s00775-007-0262-6

8. METAL-BASED ENVIRONMENTAL CHEMISTRY SESSION LECTURE SL109 Vanadium detoxification: chemical and biochemical aspects Enrique J. Baran, Centro de Química Inorgánica, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina. Contact e-mail: [email protected] Environmental contamination by vanadium has dramatically increased during the last years due to the widespread use of fossil fuels, many of which liberate finely particulate V2O5 to the atmosphere during combustion. Therefore, the toxicology and detoxification of vanadium constitute areas of increasing interest. Atmospheric suspended V2O5, affects mainly the upper respiratory tract and eyes. The degree of toxicity of other vanadium compounds depends on the route of administration, oxidation state and chemical form of vanadium and it is also to some extent species-dependent. In recent years important advances for a better understanding of the metabolism of vanadium in the higher forms of life have been attained [1,2]. This knowledge allows now a safer and more rational design of new chemical detoxification procedures. In this communication the efficiency and mechanisms of action of different chelating and/or reducing-chelating agents, useful for the chemical detoxification of vanadium shall be discussed, including recent studies with the novel DMSA (meso-2,3-dimercaptosuccinic acid) and DMPS (2,3-dimercapto-1-propanesulfonic acid) ligands. On the other hand, living organisms have developed defense mechanisms to deal not only with the reactive and potentially harmful by-products arising from cellular metabolism but also to control the effects of exogenous substances that eventually invade the organism. Some peculiar aspects of these biological detoxifications processes shall also be discussed, in relation to vanadium metabolism. [1] E.J. Baran, J. Inorg. Biochem. 80, 1-10 (2000). [2] E.J. Baran, J. Braz. Chem. Soc. 14, 878-888 (2003).

ORAL PAPERS O127 Characterizing alkane-oxidation mechanisms from a number of environmentally-important metalloenzymes 1

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Rachel N. Austin , John T. Groves , Erin M. Bertrand , Sarmistha Chakrabarty3, Rahul Banerjee3, Dayi Deng2, John D. Lipscomb3, Jan B. van Beilen4, 1Bates College, Lewiston, ME, USA; 2Princeton University, Princeton, NJ, USA; 3University of Minnesota, Minneapolis, MN, USA; 4ETH Hönggerberg, Zurich, Switzerland. Contact e-mail: [email protected] Mechanistically informative chemical probes are used to characterize the activity of environmentally-important metalloenyzmes that oxidize hydrocarbons. Norcarane (bicyclo[4.1.0]heptane), and bicyclohexane are two diagnostic substrates that differ in size and rearrangement rates, facilitating a comprehensive analysis of the presence and lifetime of a radical intermediate formed during oxidation of these alkanes. Results from metalloenzyme-catalyzed oxidations of these two probes are reported. The metalloenzymes compared include cytochrome P450 (CYP) from two different bacterial strains known to oxidize alkanes, six distinct alkane monooxygenases (AlkB), soluble methane monooxygenase (sMMO) and naphthalene dioxygenase (NDO). The results -- radical lifetimes of 1 to 15 ns for AlkB and NDO, around 200 ps for sMMO, and less than 100 ps for CYP -indicate that while the oxygen-rebound mechanism appears to be the dominant mechanism used in biology to aerobically oxidize alkanes, features of the process vary with metalloenzyme structure.

O128 Inhibition effect of Tb(III) on horseradish peroxidase activity Shaofen Guo1,2, Qing Zhou2, Tianhong Lu1,3, Xiaolan Ding4, Xiaohua Huang1,2, 1College of Chemistry and Environmental Science, Nanjing Normal University, Nanjing, China; 2The Key Laboratory of Industry Biotechnology, Ministry of Education, Southern Yangtze University, Wuxi, China; 3Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, China; 4Department of Biological Science and Biotechnology, Tsinghua University, Beijing, China. Contact e-mail: [email protected] The mechanism of Tb(III), as a rare earth element inhibiting horseradish peroxidase (HRP), as an enzyme activity was investigated in plant and in the simulated physiological solution by using the combination of electron microscopic cytochemistry (EMC), cyclic voltammetry (CV), circular dichroism (CD), X-ray photoelectron spectroscopy (XPS) and fluorescence spectroscopy. It was found that Tb(III) inhibited HRP activity in plant mainly due to the interactions between Tb(III) and HRP. After horseradish leaves were pretreated with Tb(III), Tb(III) changed HRP distribution and also inhibited HRP activity in plant leaf cells, meanwhile, cell structure was destroyed. Tb(III) coordinated with oxygen in carbonyl groups in the peptide chain of HRP molecule, forming the complex of Tb(III) and HRP (Tb-HRP), changed HRP secondary and tertiary structure conformation, disturbed the microstructure of HRP heme active center and the microenvironment of fluorophore groups. The non-planarity of porphyrin cycle in heme group and exposure extent of heme active center was decreased, leading to the electron transfer of Fe(III) in porphyrin cycle of the heme group was more difficult, thus HRP activity was inhibited, this might be one of important mechanisms to explain heavy metal inhibiting peroxidase in plant cells. Acknowledgements: We thank the National Natural Science Foundation of China (20471030, 30570323) and the Foundation of State Developing and Reforming Committee (IFZ2051210). References: [1] X. Huang, S. Guo, Q. Zhou, T. Lu, X. Ding, J. Electroanal. Chem., 2007, 600, 227-235. [2] D. Pahari, A.B. Patel, D.V. Behere, J. Inorg. Biochem., 1995, 60, 245-255.

O129 Bacterial enzymes and membrane pumps for arsenic: multiple and parallel evolution Le T. Phung, Simon Silver, University of Illinois at Chicago, Department of Microbiology and Immunology (M/C 790), Chicago, IL, USA. Contact e-mail: [email protected] Microbes cope with toxic inorganic arsenic in the environment by enzymatic transformations, including reduction from As(V) to As(III) by arsenate reductase and oxidation of As(III) to As(V) by arsenite oxidase. Although counter-intuitive, both processes confer resistance. In addition, microbes methylate inorganic arsenic and microbial enzymes convert organoarsenicals to inorganic arsenic. When coupled as the electron acceptor at the end of an anaerobic respiratory electron transport chain, the cells can be said to be “breathing arsenate.” Intracellular arsenate reductases are small monomeric proteins that use cysteine thiol cascades for reduction. Cell-surface arsenate reductase and arsenite oxidase are dimeric proteins with Mo-pterin cofactors and [Fe-S] cages in both subunits, and are connected for electron transport to membrane respiratory chains. Cellular membrane proteins take up arsenate and arsenite in to the cells; and different membrane proteins confer resistance by effluxing toxic arsenic out form the cells. Surprisingly, each of these proteins, enzymes and pumps, seem to have evolved more than once, as convergent evolution provided resistance against ubiquitous toxic arsenic forms. This convergent evolution is like the

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skins of animals and of tomatoes, which arose separately but function as covers somewhat similarly. References 1. Mukhopadhyay, R., Rosen, B. P., Phung, L. T., Silver, S. 2002. Microbial arsenic: from geocycles to genes. FEMS Microbiol .Rev. 26, 311-325. 2) Silver, S., Phung, L. T. 2005. Oxidation and reduction: the microbiology of inorganic arsenic. Appl. Environ. Microbiol. 71,599-608. 3) Messens, J., Silver, S. 2006. Arsenate reduction: thiol cascade chemistry with convergent evolution. J. Mol. Biol. 362,1-17.

POSTERS P418 The effect of solvent polarity on metal ion binding by Chlorella vulgaris: an FT-IR study Maha H. Al-Qunaibit, King Saud University, Riyadh, Saudi Arabia. Contact e-mail: [email protected] Algae and microorganisms are well known for their ability to bind heavy metals. The amount of metal ion biosorbed by the alga and the mode of binding are affected by pH, concentration, hardness of metal ion and polarity of solvent and other factors. In this study a series of mixed solvents with decreasing polarity (relative to water) were employed to study the biosorption of divalent Cu, Cd and Pb ions by dead dried chlorella vulgaris. The amount adsorbed by the alga was affected by the polarity of the solvent. FT-IR spectra of the metal loaded biomass showed variations in metal binding upon change in hardness of metal ion and polarity of solvent.

P419 Distribution Aspects of Trace Elements in Some North African Wild Medicinal Herbs Ramadan I. Damja, Mokhtar Omar, Al-fateh University, Tripoli, Libyan Arab Jamahiriya. Contact e-mail: [email protected] A rather broad survey of trace elements was carried out in anumber of wild medicinal herbs known to grow in North Africa wilderness and claimed by general public to be of therapeutic importance. The herbs and their plant families were positively identified by University Botany Department. Representative samples of the herbs were carefully collected from Libyan wilderness at the end of spring 2006, stored and analyzed for their contents of macro, micronutrients and toxic trace elements. The concentration pattern of the determined elements were carefully studied regarding the concenteration of different chemical elements in the herbs, plant family , environmental aspects and the claimed therapeutic values . Interestingly, different families showed different chemical interactions and concentration trends.

P420 Fate of cancerostatic platinum compounds in biological wastewater treatment of hospital effluents Katharina Lenz, Gunda Koellensperger, Norbert Weissenbacher, Susanne Mahnik, Maria Fuerhacker, Stephan Hann, BOKUVienna, Vienna, Austria. Contact e-mail: [email protected] The presented work focuses on the fate of two cancerostatic platinum compounds (CPC), cisplatin and carboplatin, as well as of two inorganic platinum compounds, [PtCl4]2- and [PtCl6]2- in biological wastewater treatment. Laboratory experiments modelling adsorption of these compounds onto sewage sludge showed promising specific adsorption coefficients KD and KOC and Freundlich adsorption isotherms. However, the adsorption properties of the investigated

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substances were differing significantly. Adsorption decreased following the order cisplatin > [PtCl6]2- > [PtCl4]2- > carboplatin. Log KD-values were ranging from 2.5 to 4.3 , log KOC from 3.0 to 4.7. A pilot membrane bioreactor system was installed in the Vienna University Hospital and fed with wastewater from the oncologic inpatient treatment ward to investigate CPC-adsorption in a sewage treatment plant. During three monitoring periods Pt-concentrations were measured in the influent (3 - 250 μg L-1 Pt) and the effluent (2 150 μg L-1 Pt) of the treatment plant using inductively-coupled plasma mass spectrometry (ICP-MS). The monitoring periods (duration 30 days) revealed elimination efficiencies between 51% and 63% based on averaged weekly input-output budgets. The derived log KD-values and log KOC-values ranged from 2.4- 4.8 and from 2.8 5.3, respectively.

P421 Extraction of Cadmium (II) from Orthophosphoric Acid with Di(2-ethylhexyl) Phosphoric Acid Fatma Hassaine-Sadi1,2, Hafsa Bouchabou1, 1Laboratory of Electrochemistry-corrosion, Metallurgy and Inorganic Chemistry Faculty, Algiers, Algeria; 2University sciences and technology, Algiers, Algeria. Contact e-mail: [email protected] Cadmium is a heavy and highly poisonous metal. The fluxes of cadmium derive in part from zinc production (by-products in the ores of zinc), another important source of Cadmium is associated with soil after fertilizing of agricultural earths. Furthermore, cadmium is found in surface water, deriving from companies. The transportation of the cadmium from a phosphoric environment by HDEHP has been achieved. The chemical parameters have allowed to obtain variables giving the extraction efficiency optimum. Interesting performances have been realized for diluted solutions of Cd(II) (0.005M). The reactions for the extraction of Cd(II) from sulphuric acid are quite complicate because various Cd(II) species may be present. In this study, the mechanism of the Cd(II) extraction from orthophosphoric acid solutions with a kerosene solution of di(2ethylhexyl) phosphoric acid were investigated. Various compositions of Cd(II) and orthophosphoric acid, in aqueous phase were taken into account in the analysis of extractions. The determination of the distribution coefficients permitted to identify the mechanism of extraction and transfer.

P422 Crystal structure of the rubber oxygenase RoxA Maren Hoffmann1, Reinhard Braaz2, Dieter Jendrossek2, Oliver Einsle1, 1Institut für Mikrobiologie und Genetik, Göttingen, Germany; 2Institut für Mikrobiologie, Stuttgart, Germany. Contact e-mail: [email protected] Natural rubber is a hydrocarbon polymer that is one of the most important biopolymers of our time. As it does not accumulate in the environment, there has to be continuous degradation. An extracellular enzyme of Xanthomonas sp. strain 35Y was identified that was capable of polyisopropene degradation in vitro and therefore was named rubber oxygenase A [1]. We have solved the crystal structure of RoxA using multiwavelength anomalous dispersion information on the K-edge of iron and the structure was refined to 1.8 Å. RoxA represents a novel class of diheme cytochromes c and no protein with significant similarity to the overall structure of RoxA was found so far. The enzyme is monomeric and consists of one compact domain with Į-helices representing the main secondary structural motif and an unusually large portion of loops. Both heme groups are arranged in a similar way to bacterial diheme cytochrome c peroxidases suggesting that the mechanism of electron transfer might be comparable. However, peroxidase activity was not detected in the case of RoxA [1]. [1] Braaz, R., Fischer, P. and Jendrossek, D., Appl. Environ. Microbiol. 70, 7388 (2004)

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P423 Fully-automatic counting system for investigating environmental and biological materials by INAA

P425 Immobilised ionic liquids for selective removal of heavy metals from waste water

Saleh Shams Ismail, Atomic Institute, Vienna, Austria. Contact e-mail: [email protected]

Daniel Kogelnig, Anja Stojanovic, Motee Lal Sharma, Regina Krachler, Bernhard K. Keppler, Institute of Inorganic Chemistry, University of Vienna, Vienna, Austria. Contact e-mail: [email protected]

A new counting system, which consists of a sample exchanger, a counting chamber, a control unit and a software package for dynamic and optimal analytical procedure has been developed. The sample exchanger is powered pneumatically and allows up to 200 samples to be loaded automatically. The counting chamber is connected with a pneumatic device which is made from six interconnected pneumatic cylinders, enabling the chamber to move between seven counting positions (1 cm steps). The control unit primarily consists of a programmable logic controller, valves, several pneumatic cylinders and three optical sensors. The software package optimises the analytical conditions by means of two input parameters: the desired upper limit of the dead time and the shortest acceptable shaping time. The analysis sequence is based on optimising the analytical conditions, in order to keep the dead time under a certain limit (i.e., 50%). This was realized by testing the dead time for short measurement (300 ms) at the shortest sampledetector distance (i.e., 3 cm) and a shaping time of 6 μs. If the dead time is higher than that limit, the system optimises the shaping time and sample detector distance, automatically. The reproducibility of investigating Cr in different environmental and biological reference materials was found to be less than 3%.

P424 Fulvic- and humic acids as potent transport vehicles of iron in rivers

The use of organic solvents for the extraction of heavy metals from aqueous solution is a commonly used technology. However, these organic phases are usually toxic and volatile and therefore not practicable. The application of solid materials like ion exchange resins or activated charcoal is also well established but their widespread use is limited due to a lack of efficiency and selectivity or due to high costs. Here we present a new method for a selective and efficient elimination of selected heavy metals from waste water with immobilised Ionic Liquids (ILs). ILs are a new class of organic salts with melting points below 100°C. Generally they are considered as non-inflammable, have a negligible vapour pressure and a good thermal and chemical stability. We have synthesised several existing as well as completely new imidazolium, ammonium and phosphonium based ILs by a simple and cost-saving route. Subsequently these ILs were copolymerised to get polymer support immobilised ILs. The performance of surface-bound-ILs for the adsorption of selected heavy metals depending on the pH has been explored. Furthermore, the recovery of heavy metals and the recycling of these newly developed ILs-based adsorbing agents will be discussed. A schematic representation of the processes involved is given in the figure below.

Franz Jirsa1,2, Regina Krachler1, Shahram Ayromlou1, 1Institute of Inorganic Chemistry, University of Vienna, Vienna, Austria; 2Dep. of Evolutionary Biology, EF Molecular Phylogenetics, University of Vienna, Vienna, Austria. Contact e-mail: [email protected] Iron has been reported to be the limiting factor for primary production in marine ecosystems. It therefore plays a major role within the marine carbon pump, which transfers 11 to 16 Pg of carbon every year to deep ocean regions, where it is stored for at least hundreds of years. Wind erosion of rocks and transportation through air current have been believed to be the major source of iron for the oceans, neglecting the transport capacity of the continental runoff in rivers. Arguing that different iron-binding colloids become sequentially destabilized in meeting progressively increasing salinities, the partitioning of iron load from the suspended and dissolved mobile fraction to storage in the sediments was measured with high accuracy in mixtures of natural river water with artificial sea water by use of a 59Fe tracer method. The results show a characteristic sequence of sedimentation and iron is removed from the water with increasing salinity. However, the transport capacities of the investigated rivers differ significantly: waters from a river draining a sphagnum peat bog, which acts as a source of fulvic- and humic acids to the river water, contain up to 20% of the original iron load when salinity meets values of natural sea water, whereas only 5% of the original iron load persists in water with a very low content of dissolved organic carbon. This points to an important natural mechanism of iron fertilisation of oceans by terrigenous fulvic- and humic-iron complexes originating from soils and beeing transported by the continental surface-runoff.

P426 Determintation and Elimination of organotin compounds from surface and communal waters Maximillian Popp1, Lisa Fischer1, Gunda Koellensperger1, Gerhard Stingeder1, Daniel Kogelnig2, Markus Galanski2, Regina Krachler2, Bernhard Keppler2, Stephan Hann1, 1University of Natural Resources and Applied Life Sciences – BOKU Vienna, Vienna, Austria; 2University of Vienna, Institute of Inorganic Chemistry, Vienna, Austria. Contact e-mail: [email protected] With the Introduction of the new EU Water Framework Directive (2000/60/EC) high Environmental Quality Standards (EQS) for priority substances in surface water were set. Organotin compounds such as the Mono, Di- , Tri- and Tetrabutyltin (MBT, DBT, TBT and TeBT) belong to this important class of environmental pollutants. These organo-metallic compounds have a high toxicological potential and accumulate mainly in sediments and throughout the food a chain in the aquatic environment. Due to their ability to form cations they may be transported into the water phase. Therefore suitable methods for the elimination of these hazardous compounds from surface and municipal water have to be developed. Ionic liquids with their high sorption potential for cations and charged compounds were tested as media for the elimination of organotin compounds.

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Total tin was determined using inductively coupled plasma sectorfield- mass spectrometry (ICP-SFMS). Speciation of organotin compounds was performed using gas chromatography with mass spectrometric determination. Several ionic liquids were investigated with respect to their potential to remove organotin compounds from surface and municipal water. Acknowledgement: Financial support from the Austrian Federal Ministry of Agriculture, Forestry, Environment and Water Management (Project Title: “Elimination of priority substances from waste water”) is gratefully acknowledged.

P427 Mechanisms of arsenic toxicity: A thermodynamic and spectroscopic investigation of arsenite and monomethylarsenite binding to small thiols and the DNA binding domain of the glucocorticoid receptor Anne M. Spuches1, Gretchen Gehrke1,2, Benjamin Bostick2, Dean E. Wilcox1, 1Department of Chemistry, Dartmouth College, Hanover, NH, USA; 2Department of Earth Sciences, Dartmouth College, Hanover, NH, USA. Contact e-mail: [email protected] The toxicity of arsenic is believed to originate from the affinity of As3+ species for cysteine (Cys) thiols in key target proteins, including enzymes that have catalytically essential Cys residues. In spite of these known biological As-thiol interactions, the solution chemistry of As and simple thiol ligands is not well understood. Consequently, a study was undertaken to quantify the binding reactions of biologically-relevant As species with a set of simple monothiol and dithiol ligands, as well as a Zn-binding transcription factor protein. The arsenic species investigated were arsenite (As(OH)3) and monomethylarsenite (As(CH3)(OH)2), and the thiols in this study included the monothiol glutathione (GSH) and the dithiols dithiothreitol (DTT), dimercaptosuccinic acid (DMSA), and dihydrolipoic acid (DHLA). The protein investigated was the DNA binding domain of the glucocorticoid receptor (GR-DBD). The interactions were quantified by isothermal titration calorimetry (ITC) and a full thermodynamic survey of As binding to the thiols and GR-DBD was obtained. Spectroscopic measurements, including circular dichroism, Raman and EXAFS, have provided structural information on these complexes. From these studies we have been able to compare As interactions with mono- and dithiols, quantify differences between arsenite and monomethylarsenite binding to thiols, and determine the bonding differences in a series of vicinal dithiols that form 5-, 6- and 7-membered rings with As3+. We have been able to use this information to explain the binding of arsenite and monomethylarsenite to GR-DBD and develop new insight about arsenic toxicity in the cell. The data presented has many important biological implications for arsenic toxicity.

P428 Extraction of heavy metals with hydrophobic ionic liquids Anja Stojanovic, Daniel Kogelnig, Motee Lal Sharma, Regina Krachler, Bernhard K. Keppler, Institute of Inorganic Chemistry, University of Vienna, Vienna, Austria. Contact e-mail: [email protected] Ionic liquids (ILs) have been the focus of intense investigation for the last couple of years. They show unique properties including negligible vapour pressure, a large liquidus range, thermal stability, special catalytic performance and extraordinary behaviour in extraction processes. Their possible application in liquid-liquid extraction for the elimination of heavy metals from aqueous solutions has gained growing attention. Here we present hydrophobic ammonium and phosphonium based ILs with anions bearing functionalized groups. They were easily synthesised via a common preparation route. A typical task specific IL is shown in the figure below.

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The efficiency and selectivity of these hydrophobic ILs as extracting media for Pb, Cd and Ni from wastewater effluents have been investigated. Their performance for liquid-liquid extraction depending on different parameters (pH, ionic strength, matrix) as well as their leaching into the aqueous phase will be discussed. Furthermore, experiments for the back-extraction and recovery of metals were carried out. First results for metal ion stripping and a successful reuse of evaluated ILs will be presented.