Photochemical modification of proteins and tissue surface using 1,8-naphthalimides : DNA enzyme cofactors.

Our lab has long had an interest in the potential biomedical applications of naphthalimide photochemistry, including especially the use for the bonding and modification of fresh tissue. Photochemical tissue bonding represents a possible tool for the repair of tissues such as cornea, skin grafts, tendons and heart valves. Accordingly, this dissertation reports extensive mechanistic and structure-activity (SAR) studies that were performed using 4-substituted naphthalimide derivatives as sensitizers and soluble proteins or fresh tissues as substrates. The initial studies were focused on the crosslinking and modification of soluble proteins as models for tissue surfaces, and used RNAse A and lysozyme. More recent studies have been aimed at extending these studies to the modification of fresh tissue surfaces. Bovine pericardium tissue, pig skin and bovine knee meniscal tissue were used as substrates in these experiments. It was demonstrated that compounds containing dopamine, histidine, hydrazide and tyramine showed the most promising incorporation in both protein and tissue models, and similar trends were observed in both the protein models and the tissue experiments. Mechanistic studies suggested multiple photochemical mechanisms, and SAR studies identified promising naphthalimides. In a second research project small organic compounds were synthesized and studied as cofactors for the discovery of DNA enzymes. The goal was to isolate DNA enzymes that catalyzed the cleavage of a ribonucleotide phosphoester substrate assisted by the synthetic cofactor. Another goal was to develop a broader understanding of how these cofactors function by potential candidates with different structural characteristics and then identifying which characteristics enhance the catalytic activity of the DNA enzymes. Concentration, and the time of interaction of the cofactors with the DNA enzyme during the in vitro selection process, played an important role in the catalytic activity of the species.