Isolation of a Δ7-cholesterol desaturase from Tetrahymena thermophila
Cell-free preparations of Tetrahymena thermophila catalyze the direct desaturation of cholesterol to Δ7-dehydrocholesterol (provitamin D3). The activity was isolated in the microsomal fraction from Tetrahymena homogenates. Δ7-Desaturase activity was stimulated fivefold by the addition of 6 mM ATP. O...
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2000
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| Acceso en línea: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_01757598_v53_n5_p591_Valcarce http://hdl.handle.net/20.500.12110/paper_01757598_v53_n5_p591_Valcarce |
| Aporte de: |
| Sumario: | Cell-free preparations of Tetrahymena thermophila catalyze the direct desaturation of cholesterol to Δ7-dehydrocholesterol (provitamin D3). The activity was isolated in the microsomal fraction from Tetrahymena homogenates. Δ7-Desaturase activity was stimulated fivefold by the addition of 6 mM ATP. Other cofactors assayed, including NAD, NADP, NADH or NADPH, had no significant effect. The activity was found in microsomes prepared from stationary-phase cultures of the ciliate, grown either with or without added cholesterol, thus indicating that it is constitutively expressed in T. thermophila cells. |
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