Mechanism of fatty acid desaturation in the green algaChlorella vulgaris
Open Access
- 1 June 2001
- journal article
- research article
- Published by Wiley in European Journal of Biochemistry
- Vol. 268 (12) , 3545-3549
- https://doi.org/10.1046/j.1432-1327.2001.02258.x
Abstract
The hypothesis that the Δ9 desaturase of Chlorella vulgaris might operate by a synchronous mechanism has been tested using a kinetic isotope effect (KIE) approach. Thus the intermolecular primary deuterium KIE on the individual C–H bond cleavage steps involved in Δ9 desaturation have been determined by incubating growing cultures of C. vulgaris (strain 211/8K) with mixtures of the appropriate regiospecifically deuterated fatty acid analogues. Our analysis shows that the introduction of a double bond between C‐9 and C‐10 occurs in two discrete steps as the cleavage of the C9–H bond is very sensitive to isotopic substitution (kH/kd = 6.6 ± 0.3) whereas a negligible isotope effect (kH/kd = 1.05 ± 0.05) was observed for the C10–H bond‐breaking step. Similar results were obtained for linoleic acid biosynthesis (Δ12 desaturation). These data clearly rule out a synchronous mechanism for these reactions.Keywords
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