Investigations of the copper centers in proteins, phenanthrolines and polynucleotides

This work encompasses three different projects in three different copper systems with the underlying inorganic themes of bio-inorganic and photochemistry. The first project involved the mechanism of removal of copper from Rhus vernicifera tree laccase, a blue copper oxidase. Specifically, the selective removal of the type 2 copper was investigated. The mechanistic insights appear to be general in that under reducing conditions, cyanide is the key factor in scavenging the copper and removing it from the enzyme. Preliminary results, thus far, suggest that this method can be applied to the removal of copper from the mercury derivative of laccase and to a related copper protein, ceruloplasmin. Next, the photophysics of sterically crowded copper(I) phenanthrolines were studied. In general, the results show that a complex with larger substituents undergoes less structural relaxation and consequently exhibits a high-energy, long-lived emission signal. Branched substituents produce the most profound effects; however; the $\beta$-branched neopentyl in the crystal structure shows that there are obvious signs of strain. These unusual properties can be attributed to the intraligand repulsions promoting Cu-N bond elongation and intra- and inter-molecular interactions inducing a unique flattening distortion in the ground state. The last and final project incorporated concepts from both bioinorganic and photochemistry. In this project the binding interactions of a copper porphyrin, Cu(TMPyP4), with DNA was probed. As a result, we have demonstrated how it is possible to characterize the sequence dependent binding interactions of Cu(TMPyP4) through the use of DNA-hairpins. This novel approach for using DNA-hairpins will be useful for other systems in establishing sequence binding selectivity which is very important because of the relevance to the areas of mutagenesis and therapeutic applications