Photosynthesis, natural photoprotection

The photoprotective role of carotenoids is demonstrated in plant mutants that cannot synthesize essential leaf carotenoids. These mutants are lethal in nature since without carotenoids, chlorophylls degrade, their leaves are white in color, and photosynthesis cannot occur. Generally, the carotenoids are effective for visible light but have no effects in ultraviolet, gamma, or x-radiation. The reactions are listed as follows ... 

Thus, chlorophyll-based triad species can also successfully mimic the multistep strategy of natural photosynthesis to yield long-lived, energetic charge-separated states. Triad 13 and related molecules also mimic carotenoid photoprotection from singlet oxygen and carotenoid antenna function. These aspects of the molecules will be discussed in later sections. 

Allen JE and Nilsson A (1997) Redox signalhng and the structural basis of regulation of photosynthesis by protein phosphorylation. Physiol Plant 100 863-868 Anderson JM, Park Y-I and Chow WS (1997) Photoinactivation and photoprotection of Photosystem II in nature. Physiol Plant 100 214-223... 

Carotenoids are natural pigments synthesized by plants and some microorganisms. Humans and animals are not able to synthesize and need to acquire them by alimentation [1]. These compounds are widely distributed in fruits, flowers, roots, seaweeds, invertebrates, fishes, birds, bacteria, fungi, and yeasts [2-4]. They are responsible for the red, yellow, and orange colors, but green, purple, or blue color could be obtained when carotenoids are botmd with some proteins [1]. Such molecules act as photosynthesis aid and for the photoprotection of their hosts [2-4]. Due to this, it is used in food and feed as colorant, flavoring, and nutritional supplement, being source of provitamin A. 

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