Approaches to modulating the signaling pathway of nitric oxide synthase by water soluble fullerene derivatives

The field of fullerene chemistry has seen rapid growth since early 1990. Despite the insolubility of the fullerene core, water soluble fullerene derivatives can easily be prepared through a number of methods (Chapter 1). Our interest was in the preparation of compounds with similar architectures to the C₃ and D₃ carboxyfullerenes with solubilizing groups other than carboxylic acids and investigating their biological properties.; Water soluble aminofullerenes were first prepared in 2000 (Chapter 2). As amino analogues to the carboxyfullerenes, it was expected that they would possess interesting biological properties. Indeed, all of the aminofullerenes prepared to date possess the ability to inhibit nitric oxide synthase, the enzyme responsible for the production of nitric oxide (Chapter 3). The mechanism of inhibition was found to depend on the number and structure of solubilizing addends.; Monoadducts to C₆₀ were found to exhibit a greater inhibitory action against the neuronal isoform of NOS. These fullerenes apparently distort the structure of nitric oxide synthase resulting in the dissociation of reactive oxygen intermediates which act from solution to irreversibly inactivate nNOS.; The tris aminofullerenes were the most potent and mechanistically unique of the fullerenes prepared. These compounds demonstrated a high sensitivity for the neuronal and endothelial isoforms of NOS, both of which are activated by a Ca2+-dependent interaction with calmodulin. The tris aminofullerenes also interact calcineurin phosphatase, another other calmodulin regulated enzyme. Fullerene binding to calmodulin was consistent with four moles of fullerene each bound to a domain containing a Ca2+ binding site. These compounds also interacted with rabbit skeletal muscle troponin C, but not with rabbit skeletal muscle parvalbumin (both Ca2+ binding proteins), demonstrating a selectivity in inhibition.; The ability to modulate the signaling pathway of nitric oxide synthase by using water soluble fullerenes clearly warrants further investigation. Overproduction of nitric oxide is suspected in a variety of neurodegenerative diseases including both Alzheimer's and Parkinson's diseases. Compounds that control the production of NO are valuable tools allowing the mechanism of nitric oxide production to be unraveled.