Le centre actif de la 3-oxosteroide Delta1-deshydrogenase d'Arthrobacter simplex
| Autor: | Lucien Penasse, Gerard Nomine |
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| Rok vydání: | 1974 |
| Předmět: | |
| Zdroj: | European Journal of Biochemistry. 47:555-559 |
| ISSN: | 1432-1033 0014-2956 |
| DOI: | 10.1111/j.1432-1033.1974.tb03725.x |
| Popis: | The Active Center of the 3-Oxosteroid Δ1-dehydrogenase from Arthrobacter simplex The kinetic parameters of the semi-purified, hydrocortisone induced 3-oxosteroid Δ1-dehydrogenase from Arthrobacter simplex have been determined with twenty different steroids. The values thus obtained with nortestosterone and six of its stereoisomers and with derivatives bearing substituents at positions 10, 13 and 17, show that for the reaction to take place, first the presence of a 3-oxo group, a Δ4-double bond and axial hydrogens at 1α and 2β positions, are necessary, secondly no bulky substituents must be present in the middle part of the α-face and at position 4; thirdly at positions 10β and 13β no substituents with more than two carbon atoms must be present. With steroids bearing a methyl group in position 10, the chirality of this center has to be natural, and with 19-norsteroids, the conformation of the whole molecule has to be almost flat. The active center could be represented as a cleft in the protein molecule one side of which is in contact with the α-face of the steroid, the other side being located a few tenths of nanometer above the β-face, The Δ4-double bond is required for the reaction but not for binding. There is no contact point in the area of carbon atom 17. |
| Databáze: | OpenAIRE |
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