Characterization of mononuclear copper-nitrogen oxide complexes: Models of NO x binding to isolated active sites in copper proteins

Abstract

Detailed examination of the interactions of simple nitrogen oxides, NxOy n-, with metal ions has become increasingly important for understanding the role of NxOy n-species in numerous biochemically and environmentally significant processes. Metal-mediated reactions of nitrogen oxides are ubiquitous within the global nitrogen cycle, in which the various forms of nitrogen are interconverted and distributed throughout the world.1 For example, metalloenzymes containing molybdenum, iron, or copper are involved in every stage of denitrification, the dissimilatory process by which some bacteria use NO3 - and NO2 - as terminal electron acceptors to release gaseous NO, N2O, and N2 (Figure 1).2 Environmental consequences of denitrification include the depletion of sources of nitrogen necessary for plant growth and the production of the greenhouse gas and ozone destroyer N2O. Moreover, excess NO3 -, a pollutant that contributes to eutrophication of lakes and rivers, can be removed from waste water by denitrification in a useful bioremedial application.3