Comparison of highly purified sheep liver and lung nadph-cytochrome P-450 reductases by the analysis of kinetic and catalytic properties

Date

1988-1

Author

İşcan, Mesude Y.
Arınç, Emel

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1. Reductase was purified to electrophoretic homogeneity from sheep liver and lung microsomes. The specific activity of both enzymes ranged from 55 to 66 μ mol cytochrome c reduced/min/mg protein. 2. Liver and lung reductases appeared to have similar kinetic and spectral properties. Km, (NADPH) and Km (cytochrome c) values were calculated to be 14.3 ± 1.23μM and 22.2 ± 2.78 μM for liver and 11.1 ±0.70 μM and 20.0 ± 2.15μM for lung reductase, respectively. Kinetic studies showed that cytoehrome c can bind the oxidized form of the enzyme as well as its reduced form and both reductases operated through a ping-pong type mechanism. 3. These reductases cannot be distinguished on the basis of monomer molecular weights (Mr 78,000) except that the liver reductase was found to be more susceptible to proteolytic attack. 4. Both reductases supported aniline 4-hydroxylation and ethylmorphine N-demethylation reactions to the same extent in the reconstituted systems. However, sheep lung reductase appeared only 36.5 and 14.8% as effective in catalyzing benzo[a]pyrene reaction as an equivalent amount of reductase from liver in the presence of liver cytochrome P-450 and 3MC-treated rat liver cytochrome P-448, respectively.

Subject Keywords

Biochemistry, Biochemistry & Molecular Biolog

URI

https://hdl.handle.net/11511/52021

Journal

International Journal of Biochemistry

DOI

https://doi.org/10.1016/0020-711x(88)90218-2

Collections

Department of Biology, Article

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Citation Formats

M. Y. İşcan and E. Arınç, “Comparison of highly purified sheep liver and lung nadph-cytochrome P-450 reductases by the analysis of kinetic and catalytic properties,” International Journal of Biochemistry, pp. 1189–1196, 1988, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/52021.