The light-harvesting (or antenna) complex of plants is an array of protein and chlorophyll molecules embedded in the thylakoid membrane which transfer light energy to one chlorophyll a molecule at the reaction center of a photosystem. The antenna pigments are predominantly chlorophyll a, chlorophyll b and carotenoids. Their absorption spectra are non-overlapping in order to broaden the range of light that can be absorbed in photosynthesis.

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  • The light-harvesting (or antenna) complex of plants is an array of protein and chlorophyll molecules embedded in the thylakoid membrane which transfer light energy to one chlorophyll a molecule at the reaction center of a photosystem. The antenna pigments are predominantly chlorophyll a, chlorophyll b and carotenoids. Their absorption spectra are non-overlapping in order to broaden the range of light that can be absorbed in photosynthesis. The carotenoids have another role as an antioxidant to prevent photo-oxidative damage of chlorophyll molecules. Each antenna complex has between 250 and 400 pigment molecules and the energy they absorb is shuttled by resonance energy transfer to a specialized chlorophyll-protein complex known as the reaction center of each photosystem. The reaction center initiates a complex series of chemical reactions that capture energy in the form of chemical bonds. For photosystem II, when either of the two chorophyll a molecules at the reaction center absorb energy, an electron is excited and transferred to an electron acceptor molecule, phaeophytin, leaving the chlorophyll a in an oxidized state. The oxidised chlorophyll a replaces the electrons by photolysis that involves the reduction of water molecules to oxygen, protons and electrons. Under changing light conditions, the reversible phosphorylation of light harvesting chlorophyll a/b binding proteins (LHCII) represents a system for balancing the excitation energy between the two photosystems. The N-terminus of the chlorophyll A-B binding protein extends into the stroma where it is involved with adhesion of granal membranes and photo-regulated by reversible phosphorylation of its threonine residues. Both these processes are believed to mediate the distribution of excitation energy between photosystems I and II. This family also includes the photosystem II protein PsbS, which plays a role in energy-dependent quenching that increases thermal dissipation of excess absorbed light energy in the photosystem.
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  • Light-Harvesting Complex II
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  • A:68-236 I:66-234
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  • PF00504
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  • Chloroa_b-bind
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  • 250 (xsd:integer)
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  • The light-harvesting (or antenna) complex of plants is an array of protein and chlorophyll molecules embedded in the thylakoid membrane which transfer light energy to one chlorophyll a molecule at the reaction center of a photosystem. The antenna pigments are predominantly chlorophyll a, chlorophyll b and carotenoids. Their absorption spectra are non-overlapping in order to broaden the range of light that can be absorbed in photosynthesis.
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  • Light-harvesting complexes of green plants
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