Nitric oxide (NO) traffic in endothelial NO synthase. Evidence for a new NO bind

2019-07-09 09:57:34

new NO site oxide heme

责任者: Slama-Schwok, Anny;Negrerie, Michel;Berka, Vladimir;Lambry, Jean-Christophe;Tsai, Ah-Lim;Vos, Marten H.;Martin, Jean-Louis 单位: Laboratory for Biosciences, CNRS Unite Mixte de Rech. 7645, Ecole Polytechnique, 91128 Palaiseau, France 来源出处: Journal of Biological Chemistry,2002,277(9):7581-7586 摘要: Nitric oxide (NO) traffic within the reduced ferrous-nitrosyl complex of endothelial nitric-oxide synthase (eNOS) has been studied by ultrafast time-resolved absorption spectroscopy. In the presence of tetrahydrobiopterin, the rate of NO rebinding to the heme upon photodissociation depends on the NO concentration. The time scale of this process, picoseconds to nanoseconds, precludes a diffusion from the solution toward the protein medium, and altogether the data point at a new NO binding site within the protein. Comparison of the kinetics of pterin-bound and -depleted eNOS points out that the existence of this new site depends on the presence of tetrahydrobiopterin. The new non-heme site may act as a doorstep to the heme pocket and control NO escape from eNOS. 关键词: Biochemistry;Nitrogen oxides;Enzymes;Photodissociation;Absorption spectroscopy;Binding sites