S-nitrosothiols undergo homolytic decomposition in aqueous solution to release NO and are also able to transfer the NO+ group to other thiolates to generate Snitrosothiols, which may undergo more facile homolysis. These reactions are probably of some significance in intracellular processes, while the use of S-nitrosothiols as sources of NO is well known, although the possibility of transnitrosation has not always been considered. However, it is possible that some of the biochemistry of Snitrosothiols takes place in cell walls and that their lipophilicity is an important factor in controlling reactivity. Fo/ these reasons, a major part of this thesis has been concerned with the study of the kinetics of decomposition S-nitroso-Nacetylpenicillarnine (SNAP) in a number of non-aqueous solvents, including Noctanol, which is often used to model the lipophilicity of cell membranes. Octanolwater partition coefficients have been measured for SNAP and GSNO (Snitrosoglutathione) and shown to be 0.36 and -1.87 respectively. The reactions of the linear tetrapyrroles biliverdin and bilirubin with some reactive nitrogen oxide species has also been studied. Bilirubin was once regarded as a waste product from the break down of the haem group that is catalysed by the enzyme haem oxygenase. However it now appears that bilirubin acts as a major antioxidant, undergoing oxidation to biliverdin. It has been shown in this thesis that bilirubin also reacts with reactive nitrogen species that cause nitrosative stress. This suggests that bilirubin is a major factor in combating cellular stress in general.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:487754 |
| Date | January 2007 |
| Creators | Aga, Rubina Gul |
| Publisher | King's College London (University of London) |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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