No description available.

No description available.

Every aerobic organism expresses cytochrome c oxidase to catalyze reduction of molecular oxygen to water, and takes advantage of this energy releasing reaction to produce an electrochemical gradient used in cellular energy production. The protein SCO (Synthesis of cytochrome c oxidase) is a required assembly factor for the oxidase, conserved across many species. SCO is implicated in the assembly of one of two copper centres (ie., CuA) of cytochrome oxidase. The exact mechanism of SCO’s participation in CuA assembly is not known. SCO has been proposed to bind and deliver copper, or alternatively to act in reductive preparation of the CuA site within the oxidase. In this body of work, the strength and stability of Cu(II) binding to Bacillus subtilis SCO is explored via electronic absorption and fluorescence spectroscopies and by calorimetric methods. An equilibrium dissociation constant (Kd) of 3.5x10-12 M was determined as an upper limit for the BsSCO-Cu(II) interaction, via differential scanning calorimetry. In the first reported case for a SCO homolog, dissociation kinetics of Cu(II) from BsSCO were characterized, and found to be dependent on both ionic strength and the presence of free Cu(II) in solution. Further differential scanning calorimetry experiments performed at high ionic strength support a two-step model of BsSCO and Cu(II) binding. The implications of this model for the BsSCO-Cu(II) interaction are presented in relation to the mechanism of interaction between SCO and the CuA site of cytochrome c oxidase. / Thesis (Master, Biochemistry) -- Queen's University, 2007-09-21 16:00:23.621

No description available.

The in vitro rate and cationic composition of the fluid secreted by the Malpighian tubules of the African migratory locust, Locusta migratoria migratoroides L, was investigated in this study. The concentrations of the elements Na, K, P, S, CI, Mg and Ca within Locusta Malpighian tubule type 1 cells, and the surrounding basement membrane, were quantified. Inhibitors and stimulators of fluid production were used to perturb the normal secretory state of the tubule cells. The rate of fluid secretion under control conditions was between 1.82 and 1.33. nl min(^-1) The fluid [K(^+)] was approximately 126mM, and [Na(^+)] 51 mM. The basement membrane was characterised by high [Na] and [CI] whilst a gradient of [K](_i) was observed. [K](_i) rose from approximately 193 mmol Kg(^-1) d.w. at the basal infoldings to 481 mmol Kg(^-1) d.w. at the apical microvillar border. The central cytoplasmic [K](_i) was 348 mmol Kg(^-1) d.w., estimated as 116mM. [Na](_i) and [Cl](_i) were generally lower, being 57mM and 29mM respectively in the central cytoplasm. Only K assumed a concentration gradient. Intracellular mass dense concretions were observed. Three types were present, the first rich in P and Ca, the second, rich in S, Na and K, and the third, rich in Mg, K and Na. The fluid production inhibitors furosemide (1mM) and bafilomycin A(_1) (1µM) raised the [N(^+)] in the secreted fluid, and altered [K](_i), [Na](_i) and [CI](_i). Furosemide lowered [K](_i) but increased [Na](_i) and [Cl](_i). Bafilomycin lowered [K(^+)] in the secreted fluid, though [K](_i) increased. Both inhibitors abolished the [K](_i) gradient. Replacing K(^+) with Rb(^+) in the bathing saline slowed fluid secretion and lowered [K](_i) and [Cl](_i), though a gradient of [K](_i) was retained. Rb adopted an intracellular gradient which mirrored that of K. Rate of secretion data suggests Rb enters the cell basolaterally primarily via the Na(^+)-K(^+)-ATPase. The fluid secretion stimulator cAMP (1mM) lowered [K](_i), and raised [Na](_i) and [Cl](_i), but corpora cardiaca extract left these elements' concentrations largely unchanged. Stimulation with both corpora cardiaca extract and cAMP maintained the [K](_i) gradient. These stimulators changed the content and number of mass dense concretions present, in manner which suggested that these structures were important in ion transport. These findings support the current model of ionic transport in these cells, including the basolateral presence of an Na(^+)-K(^+)-2Cr cotransporter, and an apical proton-pumping V-type ATPase / K(^+)/nH(^+) antiport complex.

Mathematical models are often used to describe and, in some cases predict, excitable cellular behaviour that is based on observed experimental results. With the increase of computational power, it is now possible to solve such models in a relatively short time. This, along with an increasing knowledge of cellular and subcellular processes, has led to the development of a large number of complex cellular models, capable of describing a broad range of excitable cell behaviour. But the use of complex models can also lead to problems. Most models can accurately reproduce results associated with the data on which the models are based. However, results from complicated models, with large numbers of variables and parameters, are less reliable if the model is not placed under the same physiological conditions as defined by the model author. In order to test a model??s suitability and robustness over a range of physiological conditions, one needs to fit model parameters against experimental data observed under those conditions. By using the modelling standard and repository offered by CellML, model users can easily select and adapt a large number of models to set up their own applications to fit model parameters against user-supplied experimental data. However, currently there is a lack of software that can utilise CellML model for parameter fitting. In this thesis, a Java-based utility has been developed, capable of performing least square parameter optimisation for a wide range of CellML models. Using the developed software, a number of parameter fits and identifiability analyses were performed on a selected group of CellML models. It was found that most of the models were ill-formed, with larger numbers of parameters worsening model identifiability. In some cases, the usage of multiple datasets and different objective functions can improve model identifiability. Finally, the developed software was used to perform parameter optimisation against two sets of action potentials from a sinoatrial node experiment, in the absence and presence of E9031, a specific ion channel blocker.

x, 131 leaves : photos., graphs, tables ; 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, Dept. of Physical and Inorganic Chemistry, 1979

vi, 164 leaves : ill. ; 26 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, Dept. of Physical and Inorganic Chemistry, 1977

Mathematical models are often used to describe and, in some cases predict, excitable cellular behaviour that is based on observed experimental results. With the increase of computational power, it is now possible to solve such models in a relatively short time. This, along with an increasing knowledge of cellular and subcellular processes, has led to the development of a large number of complex cellular models, capable of describing a broad range of excitable cell behaviour. But the use of complex models can also lead to problems. Most models can accurately reproduce results associated with the data on which the models are based. However, results from complicated models, with large numbers of variables and parameters, are less reliable if the model is not placed under the same physiological conditions as defined by the model author. In order to test a model??s suitability and robustness over a range of physiological conditions, one needs to fit model parameters against experimental data observed under those conditions. By using the modelling standard and repository offered by CellML, model users can easily select and adapt a large number of models to set up their own applications to fit model parameters against user-supplied experimental data. However, currently there is a lack of software that can utilise CellML model for parameter fitting. In this thesis, a Java-based utility has been developed, capable of performing least square parameter optimisation for a wide range of CellML models. Using the developed software, a number of parameter fits and identifiability analyses were performed on a selected group of CellML models. It was found that most of the models were ill-formed, with larger numbers of parameters worsening model identifiability. In some cases, the usage of multiple datasets and different objective functions can improve model identifiability. Finally, the developed software was used to perform parameter optimisation against two sets of action potentials from a sinoatrial node experiment, in the absence and presence of E9031, a specific ion channel blocker.

Thesis (Ph.D.) -- University of Adelaide, Dept. of Physical and Inorganic Chemistry, 1979.