Engineering nitric oxide synthase chimeras to function as NO dioxygenases.

Engineering nitric oxide synthase chimeras to function as NO dioxygenases. J Inorg Biochem. 2016 Mar 15; Authors: Wang ZQ, Haque MM, Binder K, Sharma M, Wei CC, Stuehr DJ Abstract Nitric oxide synthases (NOSs) catalyze a two-step oxidation of l-arginine to form nitric oxide (NO) and l-citrulline. NOS contains a N-terminal oxygenase domain (NOSoxy) that is the site of NO synthesis, and a C-terminal reductase domain (NOSred) that binds nicotinamide adenine dinucleotide phosphate (NADPH), flavin adenine dinucleotide (FAD), and flavin mononucleotide (FMN) and provides electrons to the NOSoxy heme during catalysis. The three NOS isoforms in mammals inducible NOS (iNOS), neuronal NOS (nNOS), and endothelial NOS (eNOS) share high structural similarity but differ in NO release rates and catalytic properties due to differences in enzyme kinetic parameters. These parameters must be balanced for NOS enzymes to release NO, rather than consume it in a competing, inherent NO dioxygenase reaction. To improve understanding, we drew on a global catalytic model and previous findings to design three NOS chimeras that may predominantly function as NO dioxygenases: iNOSoxy/nNOSred (Wild type (WT) chimera), V346I iNOSoxy/nNOSred (V346I chimera) and iNOSoxy/S1412D nNOSred (S1412D chimera). The WT and S1412D chimeras had higher NO release than the parent iNOS, while the V346I chimera exhibited much lower NO release, consistent with expectations. Measurement...
Source: Journal of Inorganic Biochemistry - Category: Biochemistry Authors: Tags: J Inorg Biochem Source Type: research