BIOMOLECULES AND ENZYMES

Detailed explanation-1: -To generate retinoids, -carotene needs to be cleaved enzymatically. Symmetric cleavage by -carotene-15, 15′-oxygenase (CMOI) gives rise to 2 molecules of retinaldehyde, which can then be either oxidized to retinoic acid, the active form of vitamin A that acts as a transcriptional regulator (5), or reduced to retinol.

Detailed explanation-2: -Beta carotene is a vitamin A precursor (retinol) and the most important of the provitamins A. It is cleaved to form two molecules of retinal, one of which is further metabolized to form retinol and retinoic acid.

Detailed explanation-3: -One way in which beta-carotene can be converted to vitamin A is to break it apart at the center and is thought to be most important biologically. The breakdown of beta-carotene occurs in the walls of the small intestine (intestinal mucosa) and is catalyzed by the enzyme -carotene dioxygenase to form retinal.

Detailed explanation-4: --Carotene 15, 15′ monooxygenase (-CM) cleaves -carotene into two molecules of all-trans-retinal, which are subsequently metabolized into all-trans-retinol and thence to all-trans-retinyl esters or to all-trans-RA.