Beta-carotene 15,15'-dioxygenase

Beta-carotene 15,15'-dioxygenase is an enzyme that plays a crucial role in vitamin A metabolism, specifically in the conversion of beta-carotene into retinal, a direct precursor of retinol (vitamin A) and retinoic acid. This enzyme, therefore, is essential for providing the body with adequate vitamin A, which is vital for various bodily functions including vision, immune response, and cellular communication.

Function

Beta-carotene 15,15'-dioxygenase catalyzes the cleavage of beta-carotene at the 15,15'-double bond to yield two molecules of retinal. This reaction is the first step in the conversion of dietary beta-carotene into vitamin A. The enzyme is located in the intestinal mucosa, liver, and other tissues, indicating its widespread role in controlling vitamin A levels throughout the body.

Structure

The enzyme is a member of the carotenoid dioxygenase family and requires iron as a cofactor for its catalytic activity. The precise structure of beta-carotene 15,15'-dioxygenase has been elucidated through various biochemical and biophysical methods, revealing insights into its mechanism of action and how it interacts with beta-carotene and oxygen molecules during the catalytic process.

Clinical Significance

Deficiencies in beta-carotene 15,15'-dioxygenase activity can lead to vitamin A deficiency, which is a major cause of preventable blindness in children worldwide. Additionally, variations in the gene encoding this enzyme have been linked to differences in the efficiency of beta-carotene conversion into vitamin A among individuals, which can affect dietary requirements for beta-carotene and vitamin A.

Genetic Regulation

The expression of the gene encoding beta-carotene 15,15'-dioxygenase is regulated by nutritional and hormonal factors, ensuring that vitamin A production is adapted to the body's needs. Understanding the regulation of this enzyme is crucial for developing nutritional strategies to combat vitamin A deficiency and for personalized nutrition advice based on genetic makeup.

Research and Applications

Research into beta-carotene 15,15'-dioxygenase has implications for improving human health, particularly in developing strategies to increase vitamin A levels in populations at risk of deficiency. Genetic engineering and breeding of crops with increased beta-carotene content, known as biofortification, is one approach to enhance dietary intake of precursors to vitamin A.

File:Beta-Carotene.svg

Beta-Carotene molecule, the substrate for Beta-carotene 15,15'-dioxygenase.

See Also

• Vitamin A
• Carotenoid
• Retinol
• Retinoic acid
• Biofortification

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