Photosystem pigments

PP - photosystem pigment (of green sulfur bacteria) PPBQ - paraphenyl benzoquinione PQ - plastoquinone... 

Havaux, M. and F. Tardy. 1996. Temperature-dependent adjustment of the thermal stability of photosystem II in vivo Possible involvement of xanthophyll-cycle pigments. Planta 193 324—333. 

Unlike the photosynthetic apparatus of photosynthetic bacteria, that of cyanobacteria consits of two photosystems, PS I and II, connected by an electron transport chain. The only chlorophyll present is chlorophyll a, and, therefore, chlorophylls b—d are not of interest in this article. Chlorophyll a is the principal constituent of PS I. Twenty per cent of isolated pigment-protein complexes contain one P700 per 20—30 chlorophyll a molecules the other 80% contain only chlorophyll a20). The physical and chemical properties of chlorophyll a and its role in photosynthesis have recently been described by Meeks77), Mauzerall75), Hoch60), Butler10), and other authors of the Encyclopedia of Plant Physiology NS Vol. 5. 

When the trap light is utilized predominantly by photosystem II (e.g., by irradiation of 563 nm, which is absorbed by the main accessory pigment C-phycoerythrin),... 

Photosystem I is a membrane pigment-protein complex in green plants, algae as well as cyanobacteria, and undergoes redox reactions by using the electrons transferred from photosystem II (PS II) [1], These membrane proteins are considered to be especially interesting in the study of monomolecular assemblies, because their structure contains hydrophilic area that can interact with the subphase as well as hydrophobic domains that can interact either with each other or with detergent and lipids [2], Moreover, studies with such proteins directly at the air-water interface are expected to be a valuable approach for their two-dimensional crystallization. 

It is intended in the present review to critically summarize current knowledge concerning structure and function of the pigment-protein complexes of higher plant photosystems. 

The photosynthetic electron transport chain in plants starts in photosystem II (PS 11 see p. 128). PS 11 consists of numerous protein subunits (brown) that contain bound pigments—i.e., dye molecules that are involved in the absorption and transfer of light energy. 

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