FT-IR analysis of membranes of Rhodobacter sphaeroides 2.4.3 grown under microaerobic and denitrifying conditions

Fourier transform infrared spectroscopic analysis of CO binding proteins in Rhodobacter sphaeroides reveals the presence of a membrane-bound nitric oxide reductase (Nor). Nor has been clearly distinguished from the cytochrome oxidases by the temperature-dependence of relaxation following photodissociation of the CO complex at cryogenic temperatures. The center frequency and band shape, 1970 cm-1 and 20-30 cm-1 width at half-peak height, are similar to those reported for resonance Raman spectra of purified Paracoccus denitrificans Nor. Additional evidence is presented to indicate this enzyme is part of dissimilatory nitric oxide metabolism and that one of the genes in the nor operon required for production of an active Nor is not required for protein assembly or heme incorporation.