Light and photosynthesis

Heme oxygenase (HO) catalyzes the oxidative degradation of heme utilizing molecular oxygen and reducing equiva-lents. In photosynthetic organisms, HO functions in the biosynthesis of such open-chain tetrapyrroles as phyto-chromobilin and phycobilins, which are involved in the sig-nal transduction for light responses and light harvesting for photosynthesis, respectively.

9p awards 05-04-2013 31 3   Download

The cytochrome b6f complex is a dimeric protein complex that is of central importance for photosynthesis to carry out light driven electron and proton transfer in chloroplasts. One molecule of chlorophyll awas found to asso-ciate per cytochrome b6 f monomer and the structural or functional impor-tance of this is discussed.

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The efficiency of light harvesting in higher plant photosynthesis is regulated in response to external environmental conditions. Under conditions of excess light, the normally highly efficient light-harvesting system of photo-system II is switched into a state in which unwanted, potentially harmful, energy is dissipated as heat.

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In order to carry out photosynthesis, plants and algae rely on the co-opera-tive interaction of two photosystems: photosystem I and photosystem II. For maximum efficiency, each photosystem should absorb the same amount of light.

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