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Research project (§ 26 & § 27)
Duration : 2017-10-01 - 2020-09-30

Eels are an endangered species of which the migration behaviour is only little understood. In this research project, analysis of eel otoliths and eel soft tissues by means of (LA)-ICP-SFMS and (LA)-MC ICP-MS for elemental (Li, Ba, Mg, B, Fe, Zn, Sr, Ca, Mn, Zr, Pb, U, S) and 87Sr/86Sr isotope analysis. Eel of different provenance will be provided. A special focus is set on glass-eel, representing the juvenile status of the fish. Since the samples are extremely challenging, existing analytical protocols will be further developed and optimized for the respective research question. The to be developed database will be compared with water data in order to reconstruct migration and provenance of the investigated fish samples.
Research project (§ 26 & § 27)
Duration : 2018-01-01 - 2020-12-31

Chlorite dismutases (Clds) are able to efficiently decompose chlorite (ClO2-) into harmless chloride (Cl-) and dioxygen (O2) with chlorite being the sole source of dioxygen. Thereby, a covalent oxygen-oxygen bond is formed, a unique biochemical reaction that in addition is only catalyzed by the water-splitting manganese complex of photosystem II of oxygenic phototrophic organisms. The mechanism of cleavage of chlorite is still under heavy debate. Computational studies suggest homolytic cleavage, thereby producing chlorine monoxide (ClO●) and Compound II [Por…Fe(IV)=O] followed by a rebound step and release of chloride and dioxygen, whereas biochemical studies on pentameric (clade 1) Clds suggest heterolytic cleavage of chlorite thereby forming Compound I [Por+●…Fe(IV)=O] and hypochlorite (HOCl/-OCl). However, there is no experimental proof for the generation of Compound I nor is it known why these oxidoreductases have their pH optimum around pH 5 and are inactivated at alkaline pH. In order to elucidate structure-function relationships in Cld and understand the molecular basis of chlorite degradation, we have selected the dimeric Cld from Cyanothece sp. PCC7425 (CCld) as model enzyme for several reasons. CCld can easily be produced in E. coli, allows the generation of crystals of optimum size at all relevant pH values to be probed by both X-ray and neutron crystallography and for the first time showed distinct spectral features of typical heme b Compound II, which was formed immediately after mixing the ferric enzyme with chlorite. Moreover, CCld exhibits further enzymatic features that contradict the proposed heterolytic but favour the homolytic cleavage mechanism of chlorite. Thus it is the aim of this project to fully clarify the molecular mechanism of chlorite cleavage and O2 formation by using a broad set of biochemical and biophysical methods: (i) the recombinant production and purification of the wild-type protein and selected single mutants; (ii) characterization of these iron-proteins by various spectroscopic (resonance Raman, UV-vis) and electrochemical techniques, (iii) analysis of all individual reaction steps of enzyme cycle by multi-mixing stopped-flow spectroscopy and freeze-quench electron paramagnetic resonance (EPR) spectroscopy; and (iv) elucidation of X-ray and neutron crystal structures in the pH range 5-10. The work will be performed in close cooperation with internationally well-known scientists from Austria (X-ray crystallography: Kristina Djinovic-Carugo), Italy (RR spectroscopy: Giulietta Smulevich), Belgium (EPR spectroscopy: Sabine Van Doorslaer) and USA (neutron crystallography: Leighton Coates). Understanding structure-function relationships of Cld will provide the basis for its application in chemical engineering and bioremediation.
Research project (§ 26 & § 27)
Duration : 2018-01-01 - 2021-12-31

Das Austrian Biorefinery Center Tulln ist geplant als ein international führendes Zentrum in der angewandten Grundlagenforschung, basierend auf der internationalen Spitzenposition der beteiligten Institute in der Forschung und auf der Konzentration von Kompetenzen und Industrie-Kooperationen am Standort Tulln. Das BOKU ABC-T bündelt Grundlagen- und angewandte Forschung auf dem Gebiet der Bioraffinerie, der Chemie nachwachsender Rohstoffe, neuer Biomaterialien und Analytik von Bioraffinerieströmen am Technopol Tulln. In der vierjährigen ersten Projektphase werden in zehn Modulen mit zehn Formenpartnern grundlagenwissenschaftliche Forschungsfragen bearbeitet, wobei die praktische Relevanz immer durch die jeweilige Firmenkooperation sichergestellt ist.

Supervised Theses and Dissertations