| dc.contributor.author | Liu, Ning. | en_US |
| dc.date.accessioned | 2014-10-21T12:36:43Z | |
| dc.date.available | 2006 | |
| dc.date.issued | 2006 | en_US |
| dc.identifier.other | AAINR19589 | en_US |
| dc.identifier.uri | http://hdl.handle.net/10222/54827 | |
| dc.description | Recent advances in computational chemistry, especially the impressive development of density functional theory in the last 20 years, have greatly increased our understanding of many complicated reactions, including catalysis by enzymes and oxidative damage to DNA in biological systems. | en_US |
| dc.description | This thesis describes the application of density functional theory to the elucidation of the reaction mechanisms of several biological systems. The first part describes a study of the reaction mechanisms that lead to the formation of 5-guanidano-4-nitroimidazole and 8-nitroguanine in the peroxynitrite induced oxidation of guanine. Two competitive reaction mechanisms are investigated and it is shown that the guanine radical cation mechanism is preferred over the neutral guanine radical mechanism. The role of water, as catalyst and as a reactant, is also investigated. In the second part, density functional theory is used to study the regeneration of the active site of protein-tyrosine phosphatase. Two mechanisms have been proposed for the formation of the sulphenylamide intermediate and the subsequent reactivation of the catalytic site. Calculations suggest that two competitive mechanisms have similar overall energy barriers and that the preferred route will be determined by the availability of hydrogen peroxide or other oxidizing reagents. The last part describes the reversible isomerization of ribose-5-phosphate to ribulose-5-phosphate catalyzed by ribose-5-phosphate isomerase. The important role of the catalytic base, glutamic ion, in this process is fully addressed. The thesis concludes with some suggestions for future studies on other significant enzymes and on the redox potential of biomolecules. | en_US |
| dc.description | Thesis (Ph.D.)--Dalhousie University (Canada), 2006. | en_US |
| dc.language | eng | en_US |
| dc.publisher | Dalhousie University | en_US |
| dc.publisher | | en_US |
| dc.subject | Chemistry, Biochemistry. | en_US |
| dc.title | Computational studies on reactions of DNA oxidation and enzyme catalysis. | en_US |
| dc.type | text | en_US |
| dc.contributor.degree | Ph.D. | en_US |
