Biology:Delta 6 desaturase
Delta 6 desaturase (D6D or Δ-6-desaturase) is a desaturase enzyme that converts between types of fatty acids (termed 6 after omega-6 fatty acids), which are essential nutrients in the human body. The enzyme is molecularly identical across all living things (preserved across Kingdom) it is present in animals, plants, and cyanobacteria.[1][2] D6D is one of the 3 fatty acid desaturases present in humans along with Δ-5 and Δ-9, named so because it was thought to convert only omega-6 fatty acids, but actually converts some others also, and is obligatory to build the longer chain omega-3 fatty acids from other simpler fatty acids in humans [citation needed]. In humans, it is encoded by the FADS2 gene [citation needed].
Molecular activity
D6D is a desaturase enzyme, i.e. introduces a double bond in a specific position of long-chain fatty acids. Among them, it converts between various forms of Omega-3 and Omega-6 fatty acids[citation needed]:
- primarily (in humans):
- cis-linoleic acid to gamma-linolenic acid (GLA)
- Palmitic acid to Sapienic acid
- less efficiently in humans:
- ALA to Stearidonic acid, along with an elongase to provide EPA.
- Tetracosatetranoic acid to tetracosapentanoic acid, an intermediate step between EPA to DHA synthesis.
D6D is obligatory along with various elongases to convert to longer chain omega-3's, such as between ALA to EPA as well as EPA to DHA.[3]
GLA deficiencies in animals including humans have shown wide effects down the line -- Dihomogamma-linolenic acid (DGLA) and Prostaglandin E1 deficiency. PGE1 activates T lymphocytes, inhibits smooth muscle proliferation and thrombosis, is important in gonadal function and raises cyclic AMP levels in many tissues. It also affects viability of sperm.[4] and dermatitis.[4]
Variability
6D is a long chain PUFA rate limiter, has greater affinity for ALA than for linoleic acid, nevertheless many diets have far more linoleic acid present, resulting in reduced levels of alpha-Linolenic acid to EPA conversion.[5] Women tend to have higher levels of D6D due to the effects of estrogen [citation needed].
Inhibiting factors
- alcohol, radiation, diabetes
Agonists
- Moderate food restriction (up to 300%)
- Low levels of Omega-3's.
Technical reading
- EctoGEM: 1.14.19.3-RXN
Toxoplasma gondii
Felines lack D6D activity in their guts and accumulate systemic Linoleic acid.[6] This increase in Linoleic acid in cats is responsible for the sexual cycle of T. gondii be restricted to felines. Linoleic acid stimulates T. gondii sexual reproduction [7]
References
- ↑ "Fatty Acid Desaturases, Polyunsaturated Fatty Acid Regulation, and Biotechnological Advances". Nutrients 8 (1): 23. January 2016. doi:10.3390/nu8010023. PMID 26742061.
- ↑ "Structure, function, and dietary regulation of delta6, delta5, and delta9 desaturases". Annual Review of Nutrition 24: 345–76. 2004. doi:10.1146/annurev.nutr.24.121803.063211. PMID 15189125.
- ↑ Meena, Dharmendra Kumar. "HUFA and PUFA: Structures, Occurrence, Biochemistry And Their Health Benefits". Aquafind Aquatic Fish Database. http://aquafind.com/articles/HUFA-and-PUFA.php.
- ↑ 4.0 4.1 "Docosahexaenoic acid supplementation fully restores fertility and spermatogenesis in male delta-6 desaturase-null mice". Journal of Lipid Research 51 (2): 360–7. February 2010. doi:10.1194/jlr.M001180. PMID 19690334.
- ↑ Parelman, Mardi A. (May 2015). "Omegas: Dissecting the Science on Omega-3 Supplements". Today's Dietitian 17 (5): 14. http://www.todaysdietitian.com/newarchives/050515p14.shtml.
- ↑ Sinclair, A. J.; McLean, J. G.; Monger, E. A. (1979). "Metabolism of linoleic acid in the cat" (in en). Lipids 14 (11): 932–936. doi:10.1007/BF02533508. ISSN 1558-9307. PMID 513981.
- ↑ Knoll, Laura J.; Dubey, J. P.; Wilson, Sarah K.; Genova, Bruno Martorelli Di (2019-07-01). "Intestinal delta-6-desaturase activity determines host range for Toxoplasma sexual reproduction" (in en). bioRxiv: 688580. doi:10.1101/688580. https://www.biorxiv.org/content/10.1101/688580v1.
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