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 (biology)) 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 . In humans, it is encoded by the FADS2 gene .

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:

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 .

Inhibiting factors
  • alcohol, radiation, diabetes

Agonists
  • Moderate food restriction (up to 300%)
  • Low levels of Omega-3's.

Technical reading

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
  1. Lee JM, Lee H, Kang S, Park WJ (January 2016). "Fatty Acid Desaturases, Polyunsaturated Fatty Acid Regulation, and Biotechnological Advances". Nutrients. 8 (1): 23. doi:10.3390/nu8010023. PMC 4728637. PMID 26742061.
  2. Nakamura MT, Nara TY (2004). "Structure, function, and dietary regulation of delta6, delta5, and delta9 desaturases". Annual Review of Nutrition. 24: 345–76. doi:10.1146/annurev.nutr.24.121803.063211. PMID 15189125.
  3. Meena DK. "HUFA and PUFA: Structures, Occurrence, Biochemistry And Their Health Benefits". Aquafind Aquatic Fish Database.
  4. Roqueta-Rivera M, Stroud CK, Haschek WM, Akare SJ, Segre M, Brush RS, Agbaga MP, Anderson RE, Hess RA, Nakamura MT (February 2010). "Docosahexaenoic acid supplementation fully restores fertility and spermatogenesis in male delta-6 desaturase-null mice". Journal of Lipid Research. 51 (2): 360–7. doi:10.1194/jlr.M001180. PMC 2803238. PMID 19690334.
  5. Parelman MA (May 2015). "Omegas: Dissecting the Science on Omega-3 Supplements". Today's Dietitian. 17 (5): 14.
  6. Sinclair, A. J.; McLean, J. G.; Monger, E. A. (1979). "Metabolism of linoleic acid in the cat". Lipids. 14 (11): 932–936. doi:10.1007/BF02533508. ISSN 1558-9307. PMID 513981.
  7. 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". bioRxiv: 688580. doi:10.1101/688580.


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