Chloroplast membrane

Iron-sulfur centres of the chloroplast membrane. R. Malkin and A. J. Bearden, Coord. Chem. Rev., 1979, 28,1-22 (73). 

Powles, S.B. Bjorkman, O. (19826). Photoinhibition of photosynthesis effect on chlorophyll fluorescence at 77 K in intact leaves and chloroplast membranes of Nerium oleander. Planta, 156, 97-107. 

Kloppstech, K., Meyer, G., Schuster, G. Ohad, I. (1985). Synthesis, transport and localization of nuclear coded 22-kd heat-shock protein in the chloroplast membranes of peas and Chlamydomonas. EMBO Journal, 4, 1901-9. 

Chlorophyll b occurs as an accessory pigment of the light-harvesting systems in land plants and green algae, and comprises one-third (or less) of total chlorophyll. The biosynthesis of chlorophyll b has been an area of active research particularly regarding its compartmentalization in chloroplast membranes, identification of the gene for chlorophyllide a oxidase, and characterization of the enzymes involved. ... 

The individual steps of the multistep chemical reduction of COj with the aid of NADPHj require an energy supply. This supply is secured by participation of ATP molecules in these steps. The chloroplasts of plants contain few mitochondria. Hence, the ATP molecules are formed in plants not by oxidative phosphorylation of ADP but by a phosphorylation reaction coupled with the individual steps of the photosynthesis reaction, particularly with the steps in the transition from PSII to PSI. The mechanism of ATP synthesis evidently is similar to the electrochemical mechanism involved in their formation by oxidative phosphorylation owing to concentration gradients of the hydrogen ions between the two sides of internal chloroplast membranes, a certain membrane potential develops on account of which the ATP can be synthesized from ADP. Three molecules of ATP are involved in the reaction per molecule of COj. 

Horton P., Ruban, A.V., Rees D., A. Pascal, Noctor, G.D., and Young, A.J. 1991. Control of the light-harvesting function of chloroplast membranes by the proton concentration in the thylakoid lumen aggregation states of the LHCII complex and the role of zeaxanthin. FEBS Lett. 292 1-4. 

Horton, P., Wentworth, M., and Ruban, A. 2005. Control of the light harvesting function of chloroplast membranes The LHCII-aggregation model for non-photochemical quenching II. FEBS Lett. 579 4201 1206. 

Release membrane-bound PPO by sonicating 10 mL aliquot of chloroplast membrane suspension on ice for 105 s (30-s pulse followed by a 10-s rest-repeat) using a Bronson Sonifier (Model SI25), setting 3 or an alternative. 

Hutcheson SW, Buchanan BB. Polyphenol oxidation by Viciafaba chloroplast membranes studies on the latent membrane-bound polyphenol oxidase and on the mechanism of photochemical polyphenol oxidation. Plant Physiol 1966 66 1150-1154. 

Ozone changes plant cell membrane (17, 18) and chloroplast membrane permeability (19). Loss of membrane integrity is also caused by plant pathogens (20), drought (21), herbicides (22) and frost (21). 

Chloroplast membranes are remarkably rich in galactolipids, composed of a diacylglycerol with... 

FIGURE 20-15 The Pi-triose phosphate antiport system of the inner chloroplast membrane. This transporter facilitates the exchange of cytosolic P for stromal dihydroxyacetone phosphate. The products of photosynthetic carbon assimilation are thus moved into the cytosol... 

The inner chloroplast membrane is impermeable to most phosphorylated compounds, including fructose 6-phosphate, glucose 6-phosphate, and fructose 1,6-bisphos-phate. It does, however, have a specific antiporter that catalyzes the one-for-one exchange of P4 with a triose... 

An antiporter in the inner chloroplast membrane exchanges P, in the cytosol for 3-phosphoglycerate or dihydroxyacetone phosphate produced by C02 assimilation in the stroma. Oxidation of dihydroxyacetone phosphate in the cytosol generates ATP and NADH, thus moving ATP and reducing equivalents from the chloroplast to the cytosol. 

Quantitatively minor membrane components with important biological functions include ubiquinone, which is present in the inner mitochondrial membrane, and the tocopherols. Plant chloroplast membranes contain chlorophyll, carotenes, and other lipid-soluble pigments. 

All of the available evidence indicates that it is the sequence of a protein that determines its destination. Proteins targeted to pass through the inner mitochondrial or chloroplast membrane have 20- to 70-residue presequences that are rich in arginine and lysine and which are removed when the protein reaches its... 

This evidently accounts for the presence of isoprene in the breath.34 Isoprene is also formed by many plants and is released into the atmosphere in large amounts, which contribute to photochemical formation of haze. A Mg2+-dependent enzyme catalyzes the elimination of pyrophosphate.35 Isoprene emissions rise with increasing temperature, and it has been suggested that the isoprene may dissolve in chloroplast membranes and in some way confer increased heat resistance.36 37 Hydrolytic dephosphorylation can lead to dimethylallyl alcohol, which is oxidized in the liver to dimethy-lacrylyl-CoA (Eq. 22-1). 

ATP synthase, whose knobs also protrude into the stroma. A photosynthetic unit can also be defined chemically by the number of various types of molecules present in a chloroplast membrane for each four manganese atoms (Table 23-2). Separate units contain PSI and PSII. These reaction centers appear to have a different distribution within the thylakoids, the PSI units being located principally in the unstacked membranes and the PSII units in the grana stacks.255 259... 

Moreover, there is considerable evidence that PPO is not active as a phenol oxidase in chloroplasts, but is limited as a phenol oxidase by latency or lack of substrate [18]. The latent form of the enzyme can be activated by a wide variety of treatments, including detergents [19], fatty acids [20] trypsin [21] and Ca2+ [22]. The results of Tolbert [21] indicated that light could activate latent PPO because polyphenols can be oxidized photochemically by chloroplast membranes in the absence of other... 

Photoinduced Proton Transport Through CHLOROPLAST MEMBRANES... 

Photosynthesis occurs in the plant cell organelle called the chloroplast. During the process of photosynthesis, electrons are transferred from H20 to NADP+ via an electron carrier system. The energy released by electron transport is converted into the form of a proton gradient and coupled to ADP phosphorylation. In this experiment a method is introduced to demonstrate the formation of the proton gradient across the chloroplast membranes. 

Photolnduced Proton Transport Through Chloroplast Membranes... 

When electrons flow from photosystem I to photosystem II, protons are transported across the chloroplast membranes as indicated in Figure E9.1. This aspect of photosynthesis will be discussed in a later section. 

J. Ho and E. Po, Biochem. Educ. 24, 179-180 (1996). Light-induced proton transfer through chloroplast membrane. 

Just as in the case of photosynthesizing bacteria [34,35], the increase in the characteristic time of decay of P700+ with rising temperature in the interval 180-140 K may be due to conformational transitions in chloroplast membranes causing P700 and A to approach each other with decreasing temperature. 

Photoinduced Proton Transport through Chloroplast Membranes 345... 

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