Date of Award

2017

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry

Abstract

Due to its ability to transport hydrophobic materials through the bloodstream, human serum albumin has become an intriguing component for drug delivery systems. The most pressing concerns with current albumin-based systems are the risk of pathogenic transfer associated with human-sourced blood proteins, the negative effect on osmotic pressure due to administration of a large dose of albumins, the potential immune response and loss of biological activity due to heavy modification of these albumins, and the need for organic solvents for preparation of these products. Key residues in the two main drug binding sites, DS1 and DS2, are conserved in bovine serum albumin (BSA), providing a cheaper, more readily available alternative to its human counterpart. In this work, multiple BSAs were conjugated onto a single eight-armed polyethylene glycol (PEG8) backbone with one of two types of "click" reactions, the thiol-maleimide or the strain-promoted azide-alkyne cycloaddition (SPAAC). Thiol-maleimide click chemistry was used to modify the lone free sulfhydryl of BSA at Cys34. For SPAAC, a lysine was modified with one of two dibenzocyclooctyne-N-hydroxysuccinimidyl esters. Each form of PEGylated BSA was characterized in terms of yields, secondary structure, speciation, and ligand binding capabilities. Additionally, the thermal stability of each was evaluated by determination of the temperatures of aggregation and denaturation. Each species was subjected to pasteurization studies to determine if PEGylation allowed for elimination of N-acetyl-L-tryptophan and caprylate, stabilizing agents which compete with potential ligands for Drug Site II.

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.

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