Cyclic Green function

More than 600 different carotenoids from natural sources have been isolated and characterized. Physical properties and natural functions and actions of carotenoids are determined by their chemical properties, and these properties are defined by their molecular structures. Carotenoids consist of 40 carbon atoms (tetraterpenes) with conjugated double bonds. They consist of eight isoprenoid units j oined in such a manner that the arrangement of isoprenoid units is reversed at the center of the molecule so that the two central methyl groups are in a 1,6-position and the remaining nonterminal methyl groups are in a 1,5-position relationship. They can be acyclic or cyclic (mono- or bi-, alicyclic or aryl). Whereas green leaves contain unesterified hydroxy carotenoids, most carotenoids in ripe fruit are esterified with fatty acids. However, those of a few... 

When a defect is introduced into a crystalline environment, crystal translational symmetry can no longer be invoked to transform the problem into tractable form as is done in band-structure calculations. Most of the computational treatments of defects in semiconductors rely on approximations to the defect environment that fall into one of three categories cluster, supercell (or cyclic cluster), and Green s function. 

Finally, and most importantly, the two chloroplast photosystems differ significantly in their functions only PSII splits water to form oxygen, whereas only PSI transfers electrons to the final electron acceptor, NADP". Photosynthesis in chloroplasts can follow a linear or cyclic pathway, again like green and purple bacteria. The linear pathway, which we discuss first, can support carbon fixation as well as ATP synthesis. In contrast, the cyclic pathway supports only ATP synthesis and generates no reduced NADPH for use in carbon fixation. Photosynthetic algae and cyanobacteria contain two photosystems analogous to those in chloroplasts. 

A low-potential c-type cytochrome occurs in a number of blue-green algae [1-4]. The cytochrome contains one mesoheme [5] per 15500 Da polypeptide [3]. The function of the cytochrome is not known, but there is evidence suggesting a role in cyclic photophosphorylation [6]. 

With respect to fatty acid biosynthesis, plant cell suspension cultures resemble cells in green leaves of intact plants. In leaves of Flacourtiaceae, straight-chain and cyclic fatty acid biosynthesis is located in chloroplasts. The locus of this biosynthetic process in seeds, the main cyclopentenyl fatty acid-producing organ, is not known the results obtained with cultured cells may indicate localization in the cytosol. However, the model function of cell cultures should be considered with caution. 

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