Sandbox 143: Difference between revisions
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=='''Overview'''== | =='''Overview'''== | ||
Plastocyanin is an important copper-containing protein involved in photosynthesis by all higher plants and some algae namely by Enteromorpha prolifera. Plastocyanin extracted from this alga, was the first | Plastocyanin is an important copper-containing protein involved in photosynthesis by all higher plants and some algae namely by Enteromorpha prolifera. Plastocyanin extracted from this alga, was the first algal blue copper protein characterized by X-ray crystallography and one of the best characterized electron transfer protein of the photosynthetic apparatus. This protein was intensively studied between 1981 and 1994 because of these particular spectroscopic and electronic properties. The high resolution structural analysis by molecular replacement in 1989 provided an accurate description of the structure of this protein. [http://www.sciencedirect.com/science/article/pii/002228369090269R J. Mol. Biol.] Plastocyanin is an electron donor localized in the intern membrane of thylakoïd in chloroplast. This is a monomeric protein with a single polypeptide chain of 98 amino acids and one copper atom. The molecular weight of plastocyanin is around 10,500 Daltons. | ||
=='''Structure'''== | =='''Structure'''== | ||
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The copper atom bound to the plastocyanin is in the shape Cu<sup>2+</sup>. This shape of plastocyanin is reduced by the cytochrome b<sub>6</sub>f according to the following reaction : | The copper atom bound to the plastocyanin is in the shape Cu<sup>2+</sup>. This shape of plastocyanin is reduced by the cytochrome b<sub>6</sub>f according to the following reaction : | ||
Cu<sup>2+</sup>Pc + e<sup>-</sup> → Cu<sup>+</sup>Pc | :Cu<sup>2+</sup>Pc + e<sup>-</sup> → Cu<sup>+</sup>Pc | ||
The electron is given up by the cytochrome b<sub>6</sub>f and transforms plastocyanin in shape Cu<sup>2+</sup> into plastocyanin in shape Cu<sup>+</sup>. | The electron is given up by the cytochrome b<sub>6</sub>f and transforms plastocyanin in shape Cu<sup>2+</sup> into plastocyanin in shape Cu<sup>+</sup>. | ||
Then this plastocyanin diffuses through the lumen of thylakoid (remember its localisation in intern membrane of the thylakoid) until the recognition/binding occurs with the photosystem I. | Then this plastocyanin diffuses through the lumen of thylakoid (remember its localisation in intern membrane of the thylakoid) until the recognition/binding occurs with the photosystem I. | ||
Photosystem I (P700)oxidizes Cu<sup>+</sup>Pc according to the following reaction : | Photosystem I (P700) oxidizes Cu<sup>+</sup>Pc according to the following reaction : | ||
Cu<sup>+</sup>Pc → Cu<sup>2+</sup>Pc + e<sup>-</sup> | :Cu<sup>+</sup>Pc → Cu<sup>2+</sup>Pc + e<sup>-</sup> | ||
P700 become P700<sup>+</sup>. | P700 become P700<sup>+</sup>. Photosystem I, now actived, can produces NADPH. This NADPH will be used in the dark reaction of photosynthesis. | ||
=='''References'''== | =='''References'''== | ||