Interaction of Steroid Substrates with Cytochrome P-450C21-Proteoliposomes

  • Shigeki Takemori
  • Shiro Kominami


Interaction of steroid substrates with P-450C21 incorporated into the single bilayer phosphatidylcholine liposomes was studied in the equilibrium state by measuring substrate-induced spectral change. The apparent dissociation constant of the P-450C21-substrate complex increased with PC concentration in the system, showing the substrate to be partitioned between the aqueous and lipid phases. Using a stopped flow method, the binding kinetics of the substrates to P-450c21 in the liposomes and their dissociation were analyzed at a rapid equilibrium of partitioning. Based on these kinetic analysis, the substrate binding site of P-450C21 was concluded to face the lipid phase of the liposome membranes.


Lipid Phase Substrate Binding Site Liposome Membrane Dissociation Rate Constant Rapid Equilibrium 
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  1. 1.
    Takemori, S., and Kominami, S. (1984)Trends Biochem. Sci. 9, 393–396CrossRefGoogle Scholar
  2. 2.
    Arrowsmith, M., Hadgraft, J., and Kellaway, I.W. (1983) Biochim. Biophys Acta, 750, 149–156Google Scholar
  3. 3.
    Kominami, S., Ochi, H., Kobayashi, Y., and Takemori, S. (1980) J. Biol. Chem. 255, 3386–3394Google Scholar
  4. 4.
    Parry, G., Palmer, D.N., and Williams, D.J. (1976) FEBS Lett. 67, 123–129CrossRefGoogle Scholar
  5. 5.
    Kominami, S., Itoh, Y., and Takemori, S. (1986) J. Biol. Chem. 261, 2077–2083Google Scholar
  6. 6.
    Almgren, M. (1980) J. Am. Chem. Soc. 102, 7882–7887CrossRefGoogle Scholar
  7. 7.
    Backes, W.L., and Canady, W.J. (1981) J. Biol. Chem. 256, 7213–7227Google Scholar
  8. 8.
    Griffin, B.W., and Peterson, J.A. (1972) Biochemistry 11, 4740–4746CrossRefGoogle Scholar
  9. 9.
    Seybert, D.W., Lancaster, J.R., Jr., Lambeth, J.D., and Kamin, H. (1979) J. Biol. Chem. 254, 12088–12098Google Scholar
  10. 10.
    Demel, R.A., and de Kruyff, B. (1976) Biochim. Biophys r Acta 457, 109–132Google Scholar

Copyright information

© Plenum Press, New York 1987

Authors and Affiliations

  • Shigeki Takemori
    • 1
  • Shiro Kominami
    • 1
  1. 1.Faculty of Integrated Arts and SciencesHiroshima UniversityHiroshimaJapan

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