Peridinin Peridinin Peridinin is a light-harvesting apocarotenoid, a pigment associated with chlorophyll and found in the peridinin-chlorophyll-protein (PCP) light-harvesting complex in dinoflagellates, best studied in "Amphidinium carterae". Peridinin is an apocarotenoid pigment that some organisms use in photosynthesis. Many photosynthetic dinoflagellates use peridinin, which absorbs blue-green light in the 470-550nm range, outside the range accessible to chlorophyll molecules. The peridinin-chlorophyll-protein complex is a specialized molecular complex consisting of a boat-shaped protein molecule with a large central cavity that contains peridinin, chlorophyll, and lipid molecules, usually in a 4:1 ratio of peridinin to chlorophyll. Peridinin chlorophyll (PerCP) is commonly used in immunoassays
Carotenoid especially reds and purples, are due to other classes of chemicals. Carotenoids serve two key roles in plants and algae: they absorb light energy for use in photosynthesis, and they protect chlorophyll from photodamage. Carotenoids that contain unsubstituted beta-ionone rings (including beta-carotene, alpha-carotene, beta-cryptoxanthin and gamma-carotene) have vitamin A activity (meaning that they can be converted to retinol), and these and other carotenoids can also act as antioxidants. In the eye, lutein, meso-zeaxanthin, and zeaxanthin are present as macular pigments whose importance in visual function remains under clinical research in 2017. The basic building blocks of carotenoids are isopentenyl diphosphate