The purification and properties of a cd-cytochrome nitrite reductase from Paracoccus halodenitrificans

Abstract

Paracoccus halodenitrificans, grown anaerobically in the presence of nitrite, contained membrane and cytoplasmic nitrite reductases. When assayed in the presence of phenazine methosulfate and ascorbate, the membrane-bound enzyme produced nitrous oxide whereas the cytoplasmic enzyme produced nitric oxide. When both enzymes were assayed in the presence of methyl viologen and dithionite, the cytoplasmic enzyme produced ammonia. Following solubilization, the membrane-bound enzyme behaved like the cytoplasmic enzyme, producing nitric oxide in the presence of phenazine methosulfate and ascorbate, and ammonia when assayed in the presence of methyl viologen and dithionite. The cytoplasmic and membrane-bound enzymes were purified to essentially the same specific activity. Only a single nitrite-reductase activity was detected on electrophoretic gels and the electrophoretic behavior of both enzymes suggested they were identical. The spectral properties of both enzymes suggested they were cd-type cytochromes. These data suggest that the products of nitrite reduction by the cd-cytochrome nitrite reductase are determined by the location of the enzyme and the redox potential of the electron donor.

Formation of the N-N bond from nitric oxide by a membrane-bound cytochrome bc complex of nitrate-respiring (denitrifying) Pseudomonas stutzeri

“…The (23). The NO-reducing activity from this bacterium was shown to be distinct from that of a membrane-bound cytochrome cdl (23,30). The activity of the preparation with ascorbate-PMS was 0.087 U/mg of protein.…”

Localization of the cytochrome cd1 and copper nitrite reductases in denitrifying bacteria

“…3B), colloidal-gold particles were present in the periplasmic space. Membrane-associated dNirs have been reported as both loosely (7,20,26) and tightly (15) bound. Thus, the association of dNirs with membranes may influence the results of cell fractionation studies.…”

“…dNir has been identified in the cytoplasm (15,26) and on the cytoplasmic membrane (15,22,26), where it is either tightly (15) or loosely (20,26) bound. It has been found in the periplasm after spheroplast formation (2,6,24), although some activity remains associated with the spheroplast membranes (2), and as a soluble periplasmic protein (Mingawa and Zumft, 1988 [cited in reference 10]).…”

Modelling heme d1

“…Indeed, Paracoccus halodenitrificans cdl will catalyze both dissimilarity and assimilatory nitrite reduction [25]. This suggests the versatility of biological porphyrindiones and emphasizes the need for further studies of this novel macrocycle.…”