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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Detalles Bibliográficos
Autores principales: Valcarce, G., Florin-Christensen, J., Nudel, C.
Formato: JOUR
Materias:
adenosine triphosphate
delta 7 cholesterol desaturase
nicotinamide adenine dinucleotide
nicotinamide adenine dinucleotide phosphate
protozoal protein
reduced nicotinamide adenine dinucleotide
reduced nicotinamide adenine dinucleotide phosphate
unclassified drug
cholesterol
lathosterol delta 5 dehydrogenase
lathosterol delta-5-dehydrogenase
oxidoreductase
article
biotechnology
biotransformation
chemical reaction kinetics
dairy industry
enzyme activity
enzyme isolation
nonhuman
Tetrahymena thermophila
animal
culture medium
enzymology
growth, development and aging
isolation and purification
metabolism
microsome
Ciliophora
Protozoa
Animals
Cholesterol
Culture Media
Microsomes
Oxidoreductases
Oxidoreductases Acting on CH-CH Group Donors
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_01757598_v53_n5_p591_Valcarce
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
Descripción
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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