Mutation in the Flavin Mononucleotide Domain Modulates Magnetic Circular Dichroism Spectra of the iNOS Ferric Cyano Complex in a Substrate-Specific Manner

作者：Sempombe Joseph; Galinato Mary Grace I; Elmore Bradley O; Fan Weihong; Guillemette J Guy; Lehnert Nicolai; Kirk Martin L^*; Feng Changjian

来源：Inorganic Chemistry, 2011, 50(15): 6859-6861.

DOI：10.1021/ic200952c

We have obtained low-temperature magnetic circular dichroism (MCD) spectra for ferric cyano complexes of the wild type and E546N mutant of a human inducible nitric oxide synthase (iNOS) oxygenase/flavin mononucleotide (oxyFMN) construct. The mutation at the FMN domain has previously been shown to modulate the MCD spectra of the L-arginine-bound ferric iNOS heme (Sempombe, J.; et al. J. Am. Chem. Soc. 2009, 131, 6940-6941). The addition of L-arginine to the wild-type protein causes notable changes in the CN(-)-adduct MCD spectrum, while the E546N mutant spectrum is not perturbed. Moreover, the MCD spectral perturbation observed with L-arginine is absent in the CN(-) complexes incubated with N-hydroxy-L-arginine, which is the substrate for the second step of NOS catalysis. These results indicate that interdomain FMN-heme interactions exert a long-range effect on key heme axial ligand-substrate interactions that determine substrate oxidation pathways of NOS.

• 出版日期2011-8-1