Inorganic cations play decisive roles in many cellular and physiological processes and are essential components of plant nutrition. Therefore, the uptake of cations and their redistribution must be precisely controlled. Vacuolar antiporters are important elements in mediating the intracellular sequestration of these cations. CAXs (for CAtion eXchanger) are members of a multigene family and appear to predominately reside on vacuoles. Defining CAX regulation and substrate specificity have been aided by utilizing yeast as an experimental tool. Studies in plants suggest CAXs regulate apoplastic Ca2+ levels in order to optimize cell wall expansion, photosynthesis, transpiration and plant productivity. CAX studies provide the basis for making designer transporters that have been used to develop nutrient enhanced crops and plants for remediating toxic soils. In my second study, I have characterized and defined autoinhibitory domain of Arabidopsis CAX3. Several CAX transporters, including CAX1, appear to contain an approximately 40 amino acid N-terminal regulatory regions (NRR) that modulates transport through N-terminal autoinhibition. Deletion of the NRR from several CAXs (sCAX) enhances function in plant and yeast expression assays; however, to date, there are no functional assays for CAX3. In this report, we create a series of truncations in the CAX3 NRR and demonstrate activation of CAX3 in both yeast and plants by truncating a large portion of the NRR. Experiments on endomembrane-enriched vesicles isolated from yeast expressing activated CAX3 demonstrate that the gene encodes Ca2+/H+ exchange with properties distinct from CAX1. These studies demonstrate shared and unique aspects of CAX1 and CAX3 transport and regulation. My third study is to express and purify CAX proteins for X-ray crystallographic analysis. In this study, I initiated crystallization of vacuolar membrane localized CAX protein from eukaryotes. Membrane proteins continue to be challenging targets for structural biology because of their hydrophobic nature. We have demonstrated here that eukaryotic Ca2+/H+ exchanger can be successfully expressed in E. coli based expression system. Collectively, our findings suggest that CAX protein can be successfully expressed, detergent solublized and purified from E. coli with a yield sufficient for functional and structural studies.

Requirements of high performing engine oil are today necessary since the development of new machinery with modern standardsis a cutting edge technology demanding highly optimized components. One way of increasing the lubricating properties of engineoil is through the addition of antioxidants. Antioxidants included in lubricants have a number of functions, one being buffering theinorganic acids sulphuric acid and nitric acid.A novel method expected to lower the hydrogen ion concentration in acidified engine oil was evaluated in this thesis. Thecapability of four different types of cation exchangers to serve as complements for buffering additives in heavy vehicle engineswas assessed. Two cation exchangers were weak and two were strong. The analysis techniques used to evaluate what effect thecation exchangers have on engine oil were standard test method ASTM D4739, for measurements of the total base number (TBN),and inductively coupled plasma – atomic emission spectroscopy (ICP-AES). With ASTM D4739 it was found that weak cationexchangers give positive results with respect to the ability to decrease the hydrogen ion concentration in acidified engine oil.However, after begin subjected to strong cation exchangers, ASTM D4739 indicated that the hydrogen ion concentration in theacidified engine oil remains the same or increases.With additional literature studies of a variety of cation exchangers currently on the market, further optimization of the cationexchanging material could likely be achieved. In addition, the preparation method used during the evaluation of the cationexchangers should be optimized to give more reliable results.

Zur selektiven Entfernung von Schwermetallen aus industriellen Abwässern und Prozesslösungen der metallverarbeitenden Industrie werden synthetische metallkomplexierende funktionelle Polymere – mit Iminodiessigsäure (IDE) als aktive Spezies – seit Jahren erfolgreich zur Eliminierung störender Kationen eingesetzt. Ständig steigende Anforderungen an die Qualität der aufzubereitenden Wässer verlangen nach leistungsfähigen Selektivaustauschern, die den Erhalt der Eigenschaften von Prozesslösungen (z. B. pH-Wert, Salzgehalt) ermöglichen. Ziel der Untersuchungen war es, die strukturellen Matrixeinflüsse auf Beladung, Kapazität, Selektivität und Kinetik durch Variation der Matrix und der experimentellen Bedingungen näher zu untersuchen. Auf Basis einer monodispersen Erstsubstitution eines Styren-Divinylbenzen-Copolymerisates wurde durch gezielten Einbau funktioneller Gruppen – Synthese mit differenziertem Substitutionsgrad (TK/N 1-2) – versucht, systematisch den Einfluss des Substitutionsgrades der Matrix auf die Eigenschaften der Ionenaustauscher zu analysieren. Methodisch geordnet wurden zunächst die Versuche nach dem Batch- und anschließend nach dem Säulenverfahren durchgeführt und parallel dazu die Matrix charakterisiert. Das Verhalten der funktionellen Ankergruppen in Abhängigkeit vom pH-Wert der Lösung (pH-Bereich 2 - 5) wurde untersucht, der optimale Anreicherungs-pH-Wert, die maximale Beladung (Kapazität) und Selektivität der unterschiedlich substituierten Proben für die Schwermetall-Ionen Cu, Zn, Ni, Cd, Pb und Co ermittelt. Den statischen Versuchen folgten dynamische Untersuchungen im Säulenverfahren. Ziel war die Ermittlung des Durchbruchverhaltens und der Durchbruchkapazität bei optimalem pH-Wert in Abhängigkeit vom Substitutionsgrad gegenüber den Einzelmetallionen (Cu, Ni, Zn) und ausgewählten Paaren (Cu/Ni, Cu/Zn, Ni/Zn). Alle Ionenaustauscher wurden ausschließlich in der Ca-Form eingesetzt. / Selective ion exchange offers a good solution for cleaning many waste streams. The aim of this study was to develop selective ion exchange materials for effective and economical applications in waste water treatment. The investigation of chelate resins is based on iminodiacetate with different secondary substitution (degree of substitution TK/N 1 - 2, from aminoacetic acid to iminodiacetate as functional group). As comparison the weak acid resin Lewatit TP 207 was used. The research focused on the application of selective ion exchange resins for waste effluents to ascertain the feasibility of a selective ion exchange process employing chelating cation exchangers for heavy metal removal. The metals of interest were copper (Cu), zinc (Zn), nickel (Ni), cobalt (Co), lead (Pb) and cadmium (Cd) and the resins appointed in the Ca-form. The batch operation was conducted to determine the equilibrium data and the operating resin capacity, one of the most important properties. The main equilibrium parameter affecting the ion exchange was the pH value (array 2-5). The best accumulation pH value was obtained using pH 5 for all metals. The only exception was lead with pH 3. After determining the viability of the different resins with batch systems, this study has focused on the column mode experiments. They were generated for the selected resins in the continuous ion exchange process which are essentially reserved for industrial applications. A practical application of the breakthrough curves is the determination of the breakthrough time which helps to find the best operating conditions.

В магистерской диссертации представлена методология пошагового синтеза композиционного сорбента на основе катионообменника и гидроксида титана (IV). Показаны результаты сорбции меди (II) и других тяжелых металлов синтезированным композиционным сорбентом. Для математического моделирования результатов сорбции были использованы изотермы Ленгмюра, Фрейндлиха и Темкина. Установлено, что модель Ленгмюра наиболее точно описывает сорбционный процесс. Определены константы модели Ленгмюра и площадь удельной поверхности композиционного сорбента. Гранулы композиционного сорбента изучены с помощью методов сканирующей электронной микроскопии (СЭМ) и энергодисперсионного микроанализа (ЭДМА). Вычислены коэффициенты распределения меди (II) в гранулах композиционного сорбента и степень сорбции меди (II) из водных растворов CuSO4 различной концентрации. / The methodology of stepwise synthesis of the composite sorbent based on cation exchanger and tin(IV) hydroxide was demonstrated. The sorption results of copper(II) and other heavy metals onto the composite sorbent are presented. Langmuir, Freundlich and Temkin adsorption isotherms were used in mathematical modeling of the sorption data. The Langmuir model most accurately describes the sorption process. The constants of the Langmuir model and the specific surface area of the composite sorbent were defined. Granules of the composite sorbent were studied by scanning electron microscopy (SEM) and energy-dispersive X-ray microanalysis (EDXMA). The distribution coefficients of copper(II) in the composite sorbent and the sorption degree from CuSO4 aqueous solutions of various concentrations were computed.