| Abstract
| - The electron paramagnetic resonance spectra of the heme domain ofinducible nitric oxidesynthase (iNOS) demonstrate a close relationship to the correspondingspectra of the neuronal isoform(nNOS). The binding of ligands to the iNOS arginine site perturbsthe environment of the high-spinferriheme in a highly ligand-specific manner. The iNOS formsfive-coordinate, high-spin complexeswith arginine analogs which are clearly related to the correspondingcomplexes of nNOS. Studies indicatethat the binding of l-arginine,Nω-hydroxy-l-arginine (NHA), andNω-methyl-l-arginine (NMA)producesvarious spectroscopic species closely corresponding to the equivalentcomplexes of nNOS, while Nω-nitro-l-arginine (NNA) binding produces a state whichappears intermediate in character between thenNOS NNA and arginine complexes. These spectroscopic studies havepermitted the determination ofligand-specific high-spin states which reveal similarities anddifferences between iNOS and nNOS.
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