Chemistry Commons^™

Thermodynamic Characterization Of Five Key Kinetic Parameters That Define Neuronal Nitric Oxide Synthase Catalysis, Mohammad Mahfuzul Haque, Jesus Tejero, Mekki Bayachou, Zhi-Qiang Wang, Mohammed Fadlalla, Dennis J. Stuehr

Chemistry Faculty Publications

NO synthase (NOS) enzymes convert L-arginine to NO in two sequential reactions whose rates (kcat1 and kcat2) are both limited by the rate of ferric heme reduction (kr). An enzyme ferric heme –NO complex forms as an immediate product complex and then undergoes either dissociation (at a rate that we denote as kd) to release NO in a productive manner, or reduction (kr) to form a ferrous heme –NO complex that must react with O2 (at a rate that we denote as kox) in a NO dioxygenase reaction that regenerates the ferric enzyme. The interplay of these five kinetic parameters …