Pharmaceuticals, personal care products and dissolved organic matter (OM) are introduced to soil via irrigation with reclaimed wastewater. This thesis examines the basic factors that influence sorption of these components in soil. Sorption of dissolved OM samples of varying composition to clay surfaces was examined. Results indicate that preferential sorption is dependent on clay type but not necessarily OM composition. Analysis of soils revealed aliphatic components, carbohydrates and amino acids are prevalent at the soil-water interface whereas aromatics are inaccessible at the soil-water interface. No clear relationship between sorption affinity of 17β-estradiol, sulfamethoxazole, carbamazepine and phenanthrene and soil OM aromaticity or aliphaticity was observed. A negative relationship between sorption and O-alkyl content may be due to these components blocking contaminant access to high affinity sorption sites. Therefore, application of reclaimed wastewater to soils with O-alkyl-rich OM may result in higher mobility of contaminants.

Apelin, the endogenous ligand to the apelin receptor, is a small peptide involved with cardiovascular regulation. Using nuclear magnetic resonance (NMR) spectroscopy, I demonstrate that at low temperature, residues R6-L9 and G13-F17 of apelin are more structured than the rest of the peptide. I also study the interactions of apelin with sodium dodecylsulphate (SDS), dodecylphosphocholine (DPC) and 1-palmitoyl-2-hydroxy-sn- glycero-3-[phospho-RAC-(1-glycerol)] (LPPG) micelles. Apelin binds to SDS micelles through residues R6-L9, with structure being induced in this region as well as the C- terminus of the peptide. The binding to micelles along with the corresponding change in structure make it likely that apelin binds to the apelin receptor following the membrane catalysis hypothesis. NMR spectroscopy was used to determine the structure of the N- terminal tail and first transmembrane segment of the apelin receptor (AR55) in DPC micelles. AR55 has two disrupted helices from D14-K25 and from A29-K57. The second helix is the membrane spanning region of AR55 and has a significant kink located at N46. Mutagenesis of the apelin receptor and functional assays indicate that G42, G45 and N46 are essential for the proper trafficking and function of AR. In the N-terminal tail, the functionally critical residues E20 and D23 form an anionic face that could take part in initial binding of apelin to AR. The structure of AR55 was also determined in SDS micelles, LPPG micelles and a 1:1 water: 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) solution. Overall, the micelle spanning region of AR55 has a consistent structure with a kink near N46. The N-terminal tail of AR55 is more variable, having similar structures in the micelle conditions but being largely helical in 50% HFIP. NMR relaxation experiments indicate that the N-terminal tail of AR55 undergoes much more motion in LPPG micelles compared to SDS and DPC micelles. Finally, I created a program named MC-HELAN that characterizes the kinks that occur in protein helices. I used MC- HELAN to analyze all non-redundant membrane protein structures as of March 2010. Membrane protein helix kinks are remarkably common and diverse. Initial attempts to predict membrane protein kinks using only the protein sequence were unsuccessful.

Solid state NMR has the ability to obtain detailed structural information at the molecular level in materials. This has led to the development of a large number of high resolution techniques, some of which utilize multiple pulse methods. The behaviour of these multiple pulse techniques has, to date, been explained using either relaxation or spin dynamics. Ultimately, an explanation based on a combination of both dynamics is required in order to properly understand the underlying mechanism of these techniques. This work presents an explanation of the experimental behaviour observed for three multiple pulse domain selection techniques: the DIVAM, Direct DIVAM, and Refocused DIVAM sequences. This is based on a combination of spin and relaxation dynamics and is accomplished using both analytical expressions and simulations obtained using a general simulation program for solid-state NMR spectroscopy (SIMPSON). / xviii, 179 leaves ; 29 cm

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The calcium binding epidermal growth factor-like (cbEGF) 12-13 domain pair from human fibrillin-1 was the focus of studies for this dissertation. Various nuclear magnetic resonance (NMR) spectroscopy techniques were employed to analyse the calcium binding, structural and dynamic properties of this pair, and to assess the effects of a disease-causing mutation. Fibrillin-1 is a mosaic protein composed mainly of 43 cbEGF domains arranged as multiple, tandem repeats, and mutations within fibrillin-1 have been linked to Marfan syndrome (MFS). 66% of MFS-causing mutations identified thus far are localised to cbEGF domains, emphasising that the native properties of these domains are critical to the functional integrity of this protein. The cbEGF 12-13 pair is found within the longest run of cbEGFs in fibrillin-1, and many mutations that cluster in this region are associated with the severe, neonatal form of MFS. It is thought that this region may be important for fibrillin-1 assembly into 10- 12nm connective tissue microfibrils. Calcium binding studies of cbEGF 12-13 demonstrated that cbEGF 13 contains the highest affinity site thus far investigated from human fibrillin-1. Comparison with previous results showed that fibrillin-1 cbEGF calcium binding affinity can be significantly modulated by the type of domain which is linked to its N-terminus, and also highlighted the high affinity of the "neonatal" region. The NMR solution structure of cbEGF 12-13 is a near-linear, rod-like arrangement of two cbEGF domains, with both exhibiting secondary structure characteristic of this domain type. The rod-like arrangement is stabilised by calcium binding by cbEGF 13 and by hydrophobic interdomain packing interactions. This observation supports the hypothesis that all Class I EGF/cbEGF-cbEGF pairs, characterised by a single linker residue, possess this rod-like structure. The structure also exhibits additional packing interactions to those previously observed for cbEGF32- 33 from fibrillin-1, which may explain the higher calcium binding affinity of cbEGF13. A model of cbEGF 11-15, created based on structural data for cbEGF 12-13 and a model of cbEGF32-36, has highlighted a potential protein binding interface, which encompasses all known neonatal MFS mutations, as well as a flexible, unstructured loop region of cbEGF 12. Backbone dynamics data confirmed the extended structure of cbEGF 12-13. These data, combined with previous data for cbEGF32-33, highlighted a potential dynamics signature for Class I cbEGF domain pairs. Comparison of data for these pairs also suggested that, in addition to the role of calcium in stabilising rigidity on the picoto millisecond time-scale, calcium affinity may play a key role in determining the anisotropy of cbEGF pairs. Possible dynamic explanations for the variation in calcium binding affinity of cbEGF domains from human fibrillin-1 were also noted. The Gl 127S mutation located in cbEGF 13 of fibrillin-1 causes a mild variant of MFS. NMR studies of the G1127S cbEGF12-13 mutant pair showed that cbEGF12 may chaperone folding of mutant cbEGF 13, an effect most likely mediated through interdomain packing interactions. These studies have also shown that the effects of this mutation are localised to cbEGF13, suggesting that a "partial" MFS phenotype is the result of altered structural, dynamic and/or calcium binding properties of this domain.

Most cellular magnesium is bound, yet it is the concentration of free magnesium, [Mg²⁺]_free, in red blood cells that is vital in the regulation of enzyme activity and ion transport. It is unknown how changes in total blood magnesium affect the [Mg²⁺]_free within red blood cells or in tissue, because the presence of other cations, especially H⁺ and potassium, K⁺ , affects the degree to which Mg²⁺ is bound. Consequently, this Thesis presents a new ³¹P NMR spectroscopic method to measure [Mg²⁺]_free in blood, which analyses the changes in the phosphorus chemical shifts of ATP and 2,3-DPG using theoretical equations expressing the observed chemical shift as a function of pH, K⁺ and [Mg²⁺]_free, over the pH range of 5.75 to 8.5 and [Mg²⁺]_free range 0 to 5 mM. The equations were adjusted for the binding of haemoglobin to ATP and DPG, which required knowledge of the intracellular concentrations of ATP, DPG, K⁺ and Hb. These equations enabled, for the first time, the simultaneous analyses of the chemical shifts of 3P-DPG and β-ATP to measure both intracellular 04- pH and [Mg²⁺]_free in normal and sickle blood. To simulate in vivo 100% oxygenated blood, samples were prepared for analysis by equilibration with a mixture of O₂ and CO₂, adjusted to give a pCO₂ of 40 mmHg and pO₂ > 150 mmHg. Under these conditions, normal whole blood had an intracellular pH of 7.20 ± 0.02 and a [Mg²⁺]_free of 0.41 ± 0.03 mM (n = 33). Further work determined blood pH and [Mg²⁺]_free for several clinical conditions including sickle cell anaemia, pre-eclampsia, hypoxia, patients with sub-arachnoid haemorrhage and chronic fatigue syndrome. This Thesis has demonstrated the potential of this new technique to evaluate the importance of [Mg²⁺]_free in the regulation of metabolite concentration and metabolic function, and to elucidate some of the properties of magnesium transport across the erythrocyte cell membrane.

Some physicochemical properties of several series of transition metal chalcocarbonyls such as ((eta)('6)-C(,6)H(,6))Cr(CO)(,2)(CX) and Cr(CO)(,5)(CX) (X = O, S, Se) have been investigated. In particular, the infrared, ('13)C and ('17)O nuclear magnetic resonance and ultraviolet spectra have been examined. The results show that the order of (sigma)-donor and (pi)-acceptor capabilities of the ligands is CO CS. The M((pi)) (--->) CX((pi)*) ultraviolet charge-transfer bands are shown to correlate with the respective (mu)'(,MCX) and ('13)C NMR data. Also, the ('13)C NMR chemical shifts and GQVFF force constants are found to be highly correlated. The ('17)O NMR spectra of the metal chalcocarbonyl complexes display chemical shifts in the opposite direction to the corresponding ('13)C ones. No correlation is found between the ('17)O shieldings and the other spectroscopic data. Reaction of Cr(CO)(,5)(CX) (X = S, Se) with halide ions (Y('-)) afforded mixtures of {Cr(CO)(,5)Y}('-) and trans-{Cr(CO)(,4)(CX)Y}('-) while Cr(CO)(,5)(CS) reacted with cyclohexylamine to give Cr(CO)(,5)(CNC(,6)H(,11)). The similarities and differences in the physicochemical behaviour of the metal chalcocarbonyls compared to related systems are discussed in the light of the different bonding patterns.

Includes bibliographies / x, 149 leaves : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, 1986