Characterization of the proximal ligand in the P420 form of inducible nitric oxide synthase.

ABSTRACT: The nitric oxide (NO) produced by inducible nitric oxide synthase (iNOS) up-regulates the expression of heme oxygenase (HO), which in turn produces carbon monoxide (CO) that down-regulates iNOS activity by reducing its expression level or by inhibiting its activity by converting it to an inactive P420 form (iNOS(P420)). Accordingly, CO has been considered as a potentially important attenuator of inflammation. Despite its importance, the nature of the proximal heme ligand of the iNOS(P420) species remains elusive. Here we show that the 221 cm(-1) mode of the photoproduct of iNOS(P420) does not exhibit any H(2)O-D(2)O solvent isotope shift such as that found in the iron-histidine stretching mode of myoglobin, indicating that the proximal ligand of iNOS(P420) is not a histidine. The nu(Fe-CO)

SUBMITTER: Sabat J 

PROVIDER: S-EPMC2882098 | biostudies-literature | 2009 Sep

REPOSITORIES: biostudies-literature