Fe B Mbs are structural and functional models of native bacterial nitric oxide reductases (NORs) generated through engineering of myoglobin. These biosynthetic models replicate the heme-nonheme diiron site of NORs and allow substitutions of metal centers and heme cofactors. Here, we provide evidence for multiple NOR turnover in monoformyl-heme-containing Fe B Mb1 proteins loaded with Fe II , Co II , or Zn II metal ions at the Fe B site (Fe II /Co II /Zn II -Fe B Mb1(MF-heme)). FTIR detection of the (NNO) band of N 2 O at 2231 cm -1 provides a direct quantitative measurement of the product in solution. A maximum number of turnover is observed with Fe II -Fe B Mb1(MF-heme), but the NOR activity is retained when the Fe B site is loaded with Zn II . These data support the viability of a one-electron semireduced pathway for the reduction of NO at binuclear centers in reducing conditions.
ASJC Scopus subject areas
- Colloid and Surface Chemistry