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1994 Fiscal Year Final Research Report Summary

Molecular mechanism of aldosterone biosynthesis

Research Project

Project/Area Number 05680553
Research Category

Grant-in-Aid for General Scientific Research (C)

Allocation TypeSingle-year Grants
Research Field Functional biochemistry
Research InstitutionHIROSHIMA UNIVERSITY

Principal Investigator

TAKEMORI Shigeki  Hiroshima Univ., Faculty of Int.Arts & Sciences, Professor, 総合科学部, 教授 (60019461)

Co-Investigator(Kenkyū-buntansha) YAMAZAKI Takeshi  Hiroshima Univ.Faculty of Int.Arts & Sciences, Research associates, 総合科学部, 助手 (30192397)
Project Period (FY) 1993 – 1994
KeywordsP-450 (11beta) / Steroidogenesis / Adrenal cortex / P-450 (scc) / Aldosterone / Steroid hormone
Research Abstract

In adrenal cortex, a mineralocorticoid, aldosterone, is produced in the zona glomerulasa (ZG), but not in the zonae fasciculata-reticularis (ZFR). Bovine adrenal P-450 (11beta) catalyzes the terminal steps in both aldosterone and corticosterone synthesis from deoxycorticosterone (DOC). Since bovine adrenal P-450 (11beta) is distributed throughout the three zones, the zone-specific aldosterone synthesis would not be due to difference in P-450 species in the mitochondria of each zone as demonstrated in adrenals of mouse, rat and human. Therefore, aldosterone-synthesizing activity inherent to P-450 (11beta) in ZFR must be suppressed by certain factor. Using the P-450 proteoliposomes, we noted that the suppression of the aldosterone synthesizing activity might be due to interaction between P-450 (11beta) and P-450 (scc). The difference of interactions between the two P-450 proteins in each inner mitochondrial membranes from ZG and ZFR was demonstrated using immuno-inhibition and crosslinking experiments, suggesting that P-450 (scc) modulates the activity of P-450 (11beta) within mitochondrial membranes. The reactions of corticosterone and aldosterone synthesis from DOC were studied kinetically using P-450 (11beta) -proteoliposomes and Tween 20-solubilized P-450 (11beta). The catalytic properties of the latter were virtually the same as those of proteoliposomes containing P-450 (11beta) and P-450 (scc). In the reactions of P-450 (11beta) complexed with P-450 (scc) in proteoliposomes and Tween 20-solubilized P-450 (11beta). corticosterone as an intermediate easily leaves from the catalytic site of P-450 (11beta). consequently hindering three successive monooxygenation reactions for DOC to form aldosterone as the final product.

  • Research Products

    (4 results)

All Other

All Publications (4 results)

  • [Publications] Shiro Kominami: "Regulation mechanism of the catalytic activity of bovine adrenal cytochrome P-450(11β)" Biochimica et Biophysica Acta. 1192. 234-240 (1994)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Shigeki Takemori: "Reaction mechanism of P-450 dependent steroidogenesis:Regulation of catalytic activity of bovine adrenal P-450(11β)" Cytochrome P-450:Biochemistry,Biophysics and Molecular Biology(M.C.Lechner,ed). 365-371 (1994)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Shiro Kominami: "Regulation mechanism of the catalytic activity of bovine adrenal cytochrome P-450 (11beta)" Biochimica et Biophysica Acta. 1192. 234-240 (1994)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Shigeki Takemori: "Reaction mechanism of P-450 dependent steroidogenesis : Regulation of catalytic activity of bovine adrenal P-450 (11beta)" Cytochrome P-450 : Biochemistry, Biophysics and Molecular Biology (M.C.Lechner, ed). 365-371 (1994)

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 1996-04-15  

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