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dc.creatorSethuraman, Deepaen_US
dc.date.accessioned2012-06-07T23:08:52Z
dc.date.available2012-06-07T23:08:52Z
dc.date.created2001en_US
dc.date.issued2001
dc.identifier.urihttp://hdl.handle.net/1969.1/ETD-TAMU-2001-THESIS-S48en_US
dc.descriptionDue to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to digital@library.tamu.edu, referencing the URI of the item.en_US
dc.descriptionIncludes bibliographical references (leaves 111-120).en_US
dc.descriptionIssued also on microfiche from Lange Micrographics.en_US
dc.description.abstractThe hammerhead ribozyme is a well-characterized motif that can catalyze the cleavage of a phosphodiester bond in a substrate-RNA backbone. This cleavage activity finds potential applications in ribozyme gene therapy by targeting the mRNA that code for proteins associated with diseases. Successful applications of this strategy have been demonstrated in treatment of AIDS, cancer and Alzheimer's disease. It is therefore of interest to be able to deliver the hammerhead ribozyme as a drug for therapeutic applications. PLGA (Poly-Lactide-co-Glyolide) is an FDA approved and extensively characterized biodegradable controlled release system for drug delivery. These copolymer systems are preferred over conventional modes as they release the drug at a constant rate and are more patient compliant. This work explores the drug delivery aspects of the hammerhead ribozyme from two kinds of PLGA formulations, which have a ratio of lactide to glycolide of 65:35 and 85:15. The encapsulation has been done by a pressure quench method using supercritical CO₂, a technique not explored so far for nucleic acids. Studies done in this work reveal that the ribozyme can be encapsulated and released in its active form from a PLGA formulation, in a controlled fashion. However, it is observed that slowing down the rate of release is associated with greater degradation of RNA and a reduction in activity, particularly in a formulation with increased lactide content. These effects are attributed to the acidic pH generated in the polymer environment during degradation. The three-dimensional conformation of the hammerhead ribozyme is known to be critical for its activity. Electron Paramagnetic Resonance (EPR) spectroscopy using site-directed-spin-labeling (SDSL) of the ribozyme, with nitroxide labels covalently attached to the 5'-ends of stems I and III, has been explored as a tool for conformational analysis of the ribozyme, in view of extending the studies to probe the ribozyme for conformational changes in the polymer microenvironment. The results of these studies suggest that the distances between the 5'-ends of stems I and III are greater than 25 A[] as predicted by crystallographic studies. There is also evidence for the two-step folding mechanism predicted from fluorescence studies. It is expected that the two facets explored in the current work can contribute towards achieving an efficient drug delivery vehicle for the hammerhead ribozyme, and probing conformational changes related to its activity.en_US
dc.format.mediumelectronicen_US
dc.format.mimetypeapplication/pdfen_US
dc.language.isoen_USen_US
dc.publisherTexas A&M Universityen_US
dc.rightsThis thesis was part of a retrospective digitization project authorized by the Texas A&M University Libraries in 2008. Copyright remains vested with the author(s). It is the user's responsibility to secure permission from the copyright holder(s) for re-use of the work beyond the provision of Fair Use.en_US
dc.subjectchemistry.en_US
dc.subjectMajor chemistry.en_US
dc.titleControlled release of the hammerhead ribozyme from biodegradable PLGA encapsulationen_US
dc.typeThesisen_US
thesis.degree.disciplinechemistryen_US
thesis.degree.nameM.S.en_US
thesis.degree.levelMastersen_US
dc.type.genrethesis
dc.type.materialtexten_US
dc.format.digitalOriginreformatted digitalen_US


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