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Retinyl palmitate, or vitamin A palmitate, is the ester of retinol and palmitic acid, with formula C 36 H 60 O 2. It is the most abundant form of vitamin A storage in animals. [2] An alternate spelling, retinol palmitate, which violates the -yl organic chemical naming convention for esters, is also frequently seen. [citation needed]
The enzyme 11-cis-retinyl-palmitate hydrolase (EC 3.1.1.63) catalyzes the reaction 11-cis-retinyl palmitate + H 2 O 11-cis-retinol + palmitate. This enzyme belongs to the family of hydrolases, specifically those acting on carboxylic ester bonds. The systematic name is 11-cis-retinyl-palmitate acylhydrolase.
Vitamin A occurs as two principal forms in foods: A) retinoids, found in animal-sourced foods, either as retinol or bound to a fatty acid to become a retinyl ester, and B) the carotenoids α-carotene (alpha-carotene), β-carotene, γ-carotene (gamma-carotene), and the xanthophyll beta-cryptoxanthin (all of which contain β-ionone rings) that ...
Retinyl esters can be distinguished from retinol in serum and other tissues and quantified with the use of methods such as high-performance liquid chromatography. [21] Elevated amounts of retinyl ester (i.e., >10% of total circulating vitamin A) in the fasting state have been used as markers for chronic hypervitaminosis A in humans and monkeys ...
an all-trans-retinyl ester + H 2 O = 11-cis-retinol + a fatty acid. This enzyme belongs to the family of hydrolases, specifically those acting on carboxylic ester bonds. The systematic name is all-trans-retinyl ester acylhydrolase, 11-cis retinol-forming. This enzyme participates in retinol metabolism.
First generation retinoids are produced naturally in the body and interact with their normal biological counterparts, such as retinol binding protein 4 for retinol, retinoid receptors for all-trans-retinoic acid or 9-cis-retinoic acid. [9] 13-cis retinoic acid has an unknown biological pathway but appears to act as a growth factor. [10]
In enzymology, a retinyl-palmitate esterase (EC 3.1.1.21) is an enzyme that catalyzes the chemical reaction. retinyl palmitate + H 2 O ⇌ {\displaystyle \rightleftharpoons } retinol + palmitate Thus, the two substrates of this enzyme are retinyl palmitate and H 2 O , whereas its two products are retinol and palmitate .
All-trans-retinoic acid is the major occurring retinoic acid, while isomers like 13-cis- and 9-cis-retinoic acid are also present in much lower levels. [ 6 ] The key role of all- trans -retinoic acid in embryonic development mediates the high teratogenicity of retinoid pharmaceuticals, such as isotretinoin (13- cis -retinoic acid) used for ...