The electron paramagnetic resonance spectra of purified neuronal nitric oxide synthase indicates that the binding of ligands to the arginine site perturbs the environment of the high-spin ferriheme in a highly ligand- specific manner. Four categories of high-spin complex can be distinguished; all are five-coordinate, and all retain the axial thiolate ligand, but they differ in their ligation geometries. These spectroscopic species reveal distinct local conformations which can be stabilized individually by the binding of L-arginine, N(w)-hydroxy-L-arginine, N(w)-methyl-L-arginine, and N(w)-nitro-L-arginine. Other arginine analog inhibitors stabilize one or more of these states, revealing patterns based on the nature of substituents at the terminal amino group.
ASJC Scopus subject areas