<p>This thesis contains two parts.</p><p>In the first part, general and versatile palladium-mediated <sup>11</sup>C-C bond forming reactions for use in the production of radiotracers for Positron Emission Tomography (PET) were explored. Two complimentarty approaches were investigated: the coupling of [<sup>11</sup>C]methyl iodide with a vinyl stannane and the reaction of a [<sup>11</sup>C]methylated stannane with various organohalides. The former approach resulted in an improved, fully automated method for the synthesis of the potential cell proliferation tracer 1-(2’-deoxy-2’-fluoro-β-D-arabinofuranosyl)-[<i>methyl</i>-<sup>11</sup>C]- thymine. The tracer was obtained in an isolated decay-corrected radiochemical yield of 28% at 25 min after end of radionuclide production. </p><p>In the latter approach, a [<sup>11</sup>C]methylated tricyclic stannane (5-[<sup>11</sup>C]methyl-1-aza- 5-stannabicyclo[3.3.3]undecane) was synthesised in 47% decay-corrected radiochemical yield, starting from [<sup>11</sup>C]methyl iodide. This stannane was successfully employed in palladium-mediated coupling reactions with aryl, heteroaryl and vinyl halides.</p><p>In the second part, effects of the osmolytes glycine betaine, trimethylamine <i>N</i>-oxide (TMAO) and urea on Ribonuclease A (RNase A) were investigated using Nuclear Magnetic Resonance (NMR) spectroscopy. Changes in the enzymatic activity in the presence of these osmolytes at concentrations of ≤1 M were observed by monitoring the RNase A-catalysed degradation of polyuridylic acid using <sup>31</sup>P NMR spectroscopy. The decrease in activity caused by urea was counteracted by both glycine betaine and TMAO at a molar ratio of 1:1.4 and 1:1, respectively.</p><p>To investigate if the observed activity changes were accompanied by any detectable alteration in the gross conformation of RNase A, diffusion coefficients for the enzyme in the various osmolyte solutions were measured using pulsed-field gradient NMR. A pulse sequence suitable for diffusion measurements in highly concentrated aqueous osmolyte solutions was developed and assessed. The diffusion of RNase A was measured relative to a new internal standard, 2,2,5,5,-tetramethyl-1,4-dioxane. No clear, detectable change in the relative diffusion of RNase A was observed in these media.</p>
| Identifer | oai:union.ndltd.org:UPSALLA/oai:DiVA.org:uu-5932 |
| Date | January 2005 |
| Creators | Samuelsson, Linda |
| Publisher | Uppsala University, Department of Chemistry, Uppsala : Kemiska institutionen |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Doctoral thesis, comprehensive summary, text |
| Relation | Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, 1651-6214 ; 89 |
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