An investigation of the anaerobic photoinduced binding of cis-dichlorobis(1,10 phenanthroline)rhodium (III) chloride to DNA and nucleosides

Herbert Leslie Harmon, Purdue University

Abstract

This study investigates the binding of cis-dichlorobis(1,10 phenanthroline)rhodium (III) chloride (cDCBPR) to DNA, 2$\sp\prime$ deoxyguanosine (dG) and 2$\sp\prime$ deoxyadenosine (dA) upon irradiation ($\lambda>330$ nm) under anaerobic conditions. Earlier binding studies of cDCBPR to DNA and dG under aerobic conditions indicated that the metal binds at N1 of dG. However, under these conditions the reaction was not very efficient. In this study the metal complex was found to bind at N7 of dG when irradiated with dG under anaerobic conditions, and the reaction is very efficient $(\phi>1.0)$ under these conditions. The high efficiency of this reaction is attributed to an electron transfer chain mechanism. The anaerobic binding of the metal to DNA is relatively inefficient and comparable to that observed in air. Identical products are obtained when the metal is irradiated with DNA aerobically or anaerobically, an indication that these reactions may involve the same mechanism. Sequence specificity studies of cDCBPR indicate that the metal binds preferentially to G's that are flanked by another purine and even more so to clusters of G's. The metal complex was found to only covalently bind to DNA with very little evidence for cleavage. The binding of the metal to DNA was also found to inhibit cleavage of the polynucleotide by BamH I restriction enzyme.

Degree

Ph.D.

Advisors

Morrison, Purdue University.

Subject Area

Organic chemistry|Biochemistry

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