Properties and structural requirements for substrate specificity of cytochrome <i>P</i>-450-dependent obtusifoliol 14 α-demethylase from maize (<i>Zea mays</i>) seedlings

DOI PDF 被引用文献1件
  • M Taton
    Institut de Biologie Moleculaire des Plantes, Département d'Enzymologie Cellulaire et Moléculaire, Institut de Botanique,28 rue Goethe, 67083-Strasbourg Cédex, France.
  • A Rahier
    Institut de Biologie Moleculaire des Plantes, Département d'Enzymologie Cellulaire et Moléculaire, Institut de Botanique,28 rue Goethe, 67083-Strasbourg Cédex, France.

書誌事項

公開日
1991-07-15
DOI
  • 10.1042/bj2770483
公開者
Portland Press Ltd.

この論文をさがす

説明

<jats:p>The biochemical properties of cytochrome P-450-dependent obtusifoliol 14 alpha-demthylase (P-450OBT.14DM) from maize (Zea mays) seedlings were defined. In particular, the enzyme was shown by differential centrifugation to be localized in the endoplasmic reticulum. P-450OBT.14DM had an apparent Km of 160 +/- 5 microM and an apparent Vmax of 65 +/- 5 pmol/min per mg of protein for its best substrate, obtusifoliol. The substrate specificity of P-450OBT.14DM was thoroughly investigated by comparing the demethylation of obtusifoliol with that of a series of 15 natural or novel synthetic analogues of obtusifoliol. The results obtained clearly indicate that three distinct domains of the sterol substrate are governing obtusifoliol demethylation by P-450OBT.14DM. They revealed that (i) P-450OBT.14DM has probably a specific apolar binding site for the side chain, (ii) the delta 8-double bond is an absolute requirement for substrate demethylation and (iii) the 3-hydroxy group plays a critical role in the enzyme-substrate interaction. Interestingly the binding site, beyond the C-3 position, contains a cleft which cannot accommodate a 4 beta-methyl substituent present in lanosterol or eburicol, the precursors of 14-desmethylsterols respectively in mammals and yeast. This result indicates that P-450OBT.14DM is a novel constitutive cytochrome P-450 with a high degree of substrate and product specificity.</jats:p>

収録刊行物

被引用文献 (1)*注記

もっと見る

詳細情報 詳細情報について

問題の指摘

ページトップへ