Ferrocyanide, Nitrite, and pH Dependence of ccNiR Catalyzed Reduction of Nitrite to Nitric Oxide
Mentor 1
A. Andrew Pacheco
Location
Union Wisconsin Room
Start Date
28-4-2017 1:30 PM
End Date
28-4-2017 4:00 PM
Description
Cytochrome c Nitrite Reductase (ccNiR, or NrfA) is a periplasmic, enzyme that catalyzes the six-electron reduction of nitrite to ammonia (ammonification). Under physiological conditions ccNiR catalyzes the process without release of intermediates. However, in vitro we have found it possible to trap intermediates, or to release partially reduced nitrogen species such as nitric oxide. Such experiments provide valuable insights regarding ccNiR-catalyzed ammonification of nitrite.
When the weak reductant ferrocyanide is used as the electron source, ccNiR catalyzes the one-electron reduction of nitrite to nitric oxide. Via the manipulation of individual reagents, within an anaerobic atmosphere, it has been determined that reaction rate has hyperbolic dependence on nitrite and ferrocyanide concentrations, and linear dependence on ccNiR concentration. Kinetic studies also show that the rate of NO production is pH-dependent, and that an amino acid, needs to be protonated for the enzyme to be active.
Ferrocyanide, Nitrite, and pH Dependence of ccNiR Catalyzed Reduction of Nitrite to Nitric Oxide
Union Wisconsin Room
Cytochrome c Nitrite Reductase (ccNiR, or NrfA) is a periplasmic, enzyme that catalyzes the six-electron reduction of nitrite to ammonia (ammonification). Under physiological conditions ccNiR catalyzes the process without release of intermediates. However, in vitro we have found it possible to trap intermediates, or to release partially reduced nitrogen species such as nitric oxide. Such experiments provide valuable insights regarding ccNiR-catalyzed ammonification of nitrite.
When the weak reductant ferrocyanide is used as the electron source, ccNiR catalyzes the one-electron reduction of nitrite to nitric oxide. Via the manipulation of individual reagents, within an anaerobic atmosphere, it has been determined that reaction rate has hyperbolic dependence on nitrite and ferrocyanide concentrations, and linear dependence on ccNiR concentration. Kinetic studies also show that the rate of NO production is pH-dependent, and that an amino acid, needs to be protonated for the enzyme to be active.
