Spectrophotometric activity microassay for pure and recombinant cytochrome P450-type nitric oxide reductase.
Nitric oxide reductase (NOR) of the P450 oxidoreductase family accepts electrons directly from its cofactor, NADH, to reduce two nitric oxide (NO) molecules to one nitrous oxide molecule and water. The enzyme plays a key role in the removal of radical NO produced during respiratory metabolism, and applications in bioremediation and biocatalysis have been identified. However, a rapid, accurate, and sensitive enzyme assay has not yet been developed for this enzyme family. In this study, we optimized reaction conditions for the development of a spectrophotometric NOR activity microassay using NOC-5 for the provision of NO in solution. We also demonstrate that the assay is suitable for the quantification and characterization of P450-type NOR. The K(m) and k(cat) kinetic constants obtained by this assay were comparable to the values determined by gas chromatography, but with improved convenience and cost efficiency, effectively by miniaturization. To our knowledge, this is the first study to present the quantification of NOR activity in a kinetic microassay format.
Emerging Health Technologies, Council for Science and Industrial Research in Pretoria, Brummeria, Pretoria 0091, South Africa. Electronic address: seikegarny1@gmail.com.
Seike
S
Garny
Department of Biochemistry, University of Pretoria, Pretoria, South Africa.
Jan
J
Verschoor
Emerging Health Technologies, Council for Science and Industrial Research in Pretoria, Brummeria, Pretoria 0091, South Africa.
Neil
N
Gardiner
Emerging Health Technologies, Council for Science and Industrial Research in Pretoria, Brummeria, Pretoria 0091, South Africa.
Justin
J
Jordaan
D001236:Aspergillus oryzae / Q000201:enzymology; D057075:Enzyme Assays / Q000379:methods*; D007700:Kinetics; D009243:NAD / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism*; D015203:Reproducibility of Results; D013053:Spectrophotometry
D011994:Recombinant Proteins; D009243:NAD; D009569:Nitric Oxide; D010088:Oxidoreductases; C034747:nitric-oxide reductase
Enzyme assay; NADH; Nitric oxide reductase