Date of Award

8-12-2014

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry

First Advisor

Dr. Kathryn B. Grant

Second Advisor

Dr. Dabney Dixon

Third Advisor

Dr. Gangli Wang

Abstract

Metal ions and complexes utilized as cleavage agents have influenced many synthetic approaches of scientists to assist in the cleavage and transformation of biomolecules. These metal-based synthetic cleavage agents have potential applications in biotechnology or as molecular therapeutic agents. Herein, we have examined Ce(IV) metal ion and complexes as acidic hydrolytic agents in lipid hydrolysis reactions (Chapter 2 and 3), and a copper(II) complex that photo-oxidizes DNA upon exposure to ultraviolet light (Chapter 4). In Chapter 2 we examined the hydrolysis of sphingomyelin vesicles by Ce(NH4)2(NO3)6 (Ce(IV)) and compared the results to twelve d- and f-block metal salts, hydrolysis of mixed lipid vesicles and mixed micelles of sphingomyelin by Ce(IV), and hydrolysis of phosphatidylcholine vesicles by Ce(IV), using either MALDI-TOF mass spectrometry or colorimetric assays. In Chapter 3, we described the study of a Ce(IV) complex based on 1,3-bis[tris(hydroxymethyl)methylamino]propane as a potential acidic hydrolytic agent of phospholipids using colorimetric assays and NMR spectroscopy. The hydrolytic agent provided markedly enhance hydrolysis at lysosomal pH (~ 4.8), but suppress hydrolysis when pH was raised to near-neutral pH (~ 7.2). This was due to the pKa values of the donor atoms of the ligand, in which the metal’s electrophilicity was reduced to a greater extent at ~ pH 7.2 compared to ~ pH 4.8. Chapter 4 describes the synthesis and study of a Cu(II) complex based on a hexaazatriphenylene derivative for photo-assisted cleavage of double-helical DNA. Scavenger and chemical assays suggested the formation of DNA damaging reactive oxygen species, hydroxyl and superoxide radicals, and hydrogen peroxide, in the photocleavage reactions. Thermal denaturation and UV-vis absorption studies suggested that the Cu(II) complex binds in a non-intercalative fashion to duplex DNA.

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