PS-I consists of a series of noncovalently bondend complex intrinsic polypeptides; associated with three peripheral (extrinsic) polypeptides, thought to aid in binding of Ca2+ and Cl-, both of which are essential for photolysis of water. The Light Harvesting Complex-II receives red light energy by inductive resonance from a total of about 250 chlorophyll-a and -c molecules (associated with few integral carotenoid pigments, which act as an antenna system), producing a strong oxidant (oxidizes water) and a weak reductant. PS-II recruits electrons originally released by the H2O-lysis mediated via the cytochrome complex. This reaction causes cytochrome to transport H+ protons from the stroma across the thylakoid membrane into the lumen. The PS-I core complex receives light by inductive resonance from about 100 chlorophyll-a and -c molecules formed to another antenna system (Light Harvesting Complex-I). The strong reductant produced by PS-I reduces the coenzymes NADP+ (acting as an electron-carrier) to NADPH, which is released into the stroma.
p.99-111; in ....
Raven P.H., Evert R.E., Eichhorn S.; 1992: Biology of Plants; 5th ed.; Worth Publishers; New York - USA;

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