Respiratory nitrate reductases

There are four different classes of nitrate reductases (234). The nitrate reductases from D. desulfuricans show a strong homology to the a-subunit of the class of periplasmic respiratory nitrate reductases, and also to some of the enzymes that are included on the class of cytoplasmic assimilatory nitrate reductases. Because of this fact, a proposal was made for a new class of monomeric NAP, which contains the minimal arrangement of metal centers to perform nitrate reduction one [4Fe-4S] cluster and a Mo bound to two MGD. 

Craske, A., and Ferguson, S. J. (1986). The respiratory nitrate reductase from Paracoccus denitrificans. Molecular characterization and kinetic properties. Eur.. Biochem. 158, 429-436. 

From an analysis of their protein sequences, dmso reductase, respiratory nitrate reductase, and formate dehydrogenase (FDH) are assigned as members of a large... 

IV.C.3. The Molybdenum Site of Respiratory Nitrate Reductase (Escherichia coli)... 

Respiratory nitrate reductase has considerable protein sequence homology with dmso reductases and formate dehydrogenases. Both preliminary crystallographic... 

Protein sequence homology suggests that sulfite oxidase and assimilatory nitrate reductase are members of the same molybdenum enzyme subfamily [31]. Consistent with this classification, the cofactors of sulfite oxidase and assimilatory nitrate reductase differ significantly from those in dmso reductase, aldehyde oxido-reductase, xanthine oxidase (see Section IV.E.), and even respiratory nitrate reductase (Section IV.D). The EXAFS of both sulfite oxidase [132-136] and assimilatory nitrate reductase [131,137,138] and x-ray studies of sulfite oxidase (chicken liver) [116] confirm that the molybdenum center is coordinated by two sulfur atoms from a single MPT ligand and by the sulfur atom of a cysteine side chain. The Movl state is bis(oxido) coordinated (Figure 14). 

Figure 13 The coordination geometry around molybdenum as suggested from EXAFS and genetic studies of respiratory nitrate reductase (E. coli) (a) oxidized form (b) reduced form [131],...

Kapralek, F., Jechova, E., and Otavova, M. (1982) Two sites of oxygen control in induced synthesis of respiratory nitrate reductase in Escherichia coli. J. Bacteriol. 149, 1142-1145. 

Nitrogenase MoFe protein NADH dehydrogenase Respiratory nitrate reductase Assimilatory nitrate reductase Sulfite oxidase Aldehyde oxidase Xanthine oxidase Xanthine dehydrogenase... 

Figure 12 A diagram of the nitrogen cycle with catalyzing enzymes and metal requirements of each step. NIT, nitrogenase AMO, ammonium mono-oxygenase HAO, hydroxylamine oxidoreductase NAR, membrane-bound respiratory nitrate reductase NAP, periplasmic respiratory nitrate reductase NR, assimila-tory nitrate reductase NIR, respiratory nitrite reductase NiR, assimilatory nitrite reductase NOR, nitric oxide reductase N2OR, nitrous oxide reductase.

Anderson, L.J., Richardson, D.J., and Butt, J.N. (2001) Catalytic protein film voltammetry from a respiratory nitrate reductase provides evidence for complex electrochemical modulation of enzyme activity. Biochemistry, 40, 11294-11307. 

DMSO) reductase and biotin-S-oxidoreduc-tase, as well as the bacterial dissimilatory (or respiratory) nitrate reductases (Hille 1996) (Table 18.8). The mononuclear molybdenum enzymes possess a pterin cofactor and may be categorized based on the structure of their molybdenum center... 

Moreno, R., Zafra, O., Cava, F., and Berenguer, J. (2003) Development of a gene expression vector for Jhermus thermophilus based on the promoter of the respiratory nitrate reductase. 

Figure 3.1 EPR spectra of Mo(v) species in E. coli respiratory nitrate reductase NarGHI. (A) X-band EPR spectra of enzyme with Mo in natural abundance prepared at pH = 6.0 and pH = 8.5. Arrows indicate some hyper-fine lines given by isotopes. (B) Q-band spectrum of Mo...

High-pH and Low-pHMo(v) Species in Respiratory Nitrate Reductases... 

Elliott, S.J., Hoke, K.R., Heffron, K., Palak, M., Rothery, R.A., Weiner, J.H., Armstrong, FA., 2004. Voltammetric studies of the catalytic mechanism of the respiratory nitrate reductase from Escherichia coli how nitrate reduction and inhibition depend on the oxidation state of the active site. Biochemistry 43, 799-807. 

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