Protein denitration/modification by Escherichia coli nitrate reductase and mammalian cytochrome P-450 reductase.

The incubation of peroxynitrite (PN)-pretreated histone III-S (NH) with Escherichia coli nitrate reductase (cytochrome, NADPH/GSH-independent) and that of NADPH-treated NH (NHNADPH) with liver cytochrome P-450 reductase (NADPH-dependent) resulted in decreased 3-nitrotyrosine immunoreactivity found in Western blot analysis. Additionally, increased nitrate was noted as an end product of these reactions. These findings imply that varied enzymatic denitration/modification of NO/PN-reacted protein, either with or without a reductant, may be important in regulating related signal transduction cascade(s) and relieving oxidative stress.