| | 2 | Author
| Margrit Bertrams, Käthe Wrage, Ernst Heinz | Requires cookie* | | | Title
| Lipid Labelling in Intact Chloroplasts from Exogenous Nucleotide Precursors  | | | | Abstract
| De «ovo-synthesis o f glycerolipids in chloroplasts is initiated by a stroma enzyme which catalyzes the formation o f lyso-phosphatidic acid from glycerophosphate and acyl-CoA. When these substrates are added to isolated, intact chloroplasts, only glycerophosphate can readily pass through the chloroplast envelope which represents a permeation barrier for acyl-CoA, although higher thioester concentrations destroy this membrane system. At low concentrations of acyl-CoA, which do not impair the envelope, intact chloroplasts metabolize exogenous acyl-CoA in two ways to give free fatty acids and labelled phosphatidyl choline. This indicates that the envelope thioesterase can use exogenous substrates. Isolated, intact chloroplasts fixing radioactive C 0 2 label free fatty acids and acylglycerols but not galactolipids, since they cannot convert 3-phosphoglycerate into UDP-galactose which in vivo is supplied by the cytoplasm. This cooperation was simulated in vitro by adding all enzymes and cofactors necessary for conversion of 3-phosphoglycerate into UDP-galactose to intact chloro plasts which then formed labelled monogalactosyl diacylglycerol from labelled C 0 2 . The time required to transfer envelope-made galactolipids from the envelope into thylakoids was studied by incubating intact chloroplasts with radioactive UDP-galactose, subsequent osmotic disruption of organelles with concomitant enzymatic degradation o f UDP-galactose followed by separation o f envelopes and thylakoids. Only after short times (< 1 min) appreciable pro portions (20 -30%) o f radioactive galactolipids were recovered in the envelope fraction. This in combination with previous results indicates a rapid galactolipid export from envelopes into thylakoids. | | | |
Reference
| Z. Naturforsch. 36c, 62 (1981); received September 16 1980 | | | |
Published
| 1981 | | | |
Keywords
| Acyl-CoA, UDP-Galactose, Envelope, Impermeability, Lipid Transport | | | |
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| | | | | TEI-XML for
| default:Reihe_C/36/ZNC-1981-36c-0062.pdf | | | | Identifier
| ZNC-1981-36c-0062 | | | | Volume
| 36 | |
| 3 | Author
| K.H G Rum Bach | Requires cookie* | | | Title
| Distribution of Chlorophylls, Carotenoids and Quinones in Chloroplasts of Higher Plants | | | | Abstract
| Leaves, cotyledons, isolated chloroplasts and subplastid fractions (thylakoids and envelopes) o f radish (Raphanus sativus L. cv. Saxa) and spinach (Spinacia oleracea L. cv. M atador) were assayed for their pigment and quinone content and com position. Virtually all the chlorophylls, carotenoids and quinones were contained in the thylakoids. Envelopes prepared by the method described contained very low amounts o f chlorophyll a and b, violaxanthin and neoxanthin, but no /7-carotene, lutein, zeaxanthin and antheraxanthin. Am ong the quinones trace am ounts o f plastoquinone and a-tocopherol but no plastohydroquinone, a-tocoquinone and phylloquinone were detected. Presented data may be taken as evidence that in vivo the chloroplast envelope is not a location site o f carotenoids and quinones as generally accepted. Possible im plications for the biosyntheses o f quinones and pigments are discussed. | | | |
Reference
| Z. Naturforsch. 38c, 996—1002 (1983); received August 16 1983 | | | |
Published
| 1983 | | | |
Keywords
| Carotenoids, Chlorophylls, Chloroplasts, Envelopes, Quinones, Thylakoids | | | |
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| | | | | TEI-XML for
| default:Reihe_C/38/ZNC-1983-38c-0996.pdf | | | | Identifier
| ZNC-1983-38c-0996 | | | | Volume
| 38 | |
| 4 | Author
| Christine Schindler, Ruth Hracky, Jürgen Soll | Requires cookie* | | | Title
| Protein Transport in Chloroplasts: ATP is Prerequisit | | | | Abstract
| The energy requirem ent for protein transport into chloroplast was assayed under conditions that perm it to distinguish whether the posttranslational translocation is dependent on A TP or w hether a m em brane potential across the chloroplast envelope can drive this transport event. A m em brane potential is not required for translocation. A TP can support protein transport in the presence of protonophores and ionophores. Non-hydrolyzable A TP analogues and G TP, CTP, U T P cannot serve as ATP substitutes. Translocation could be observed when an A TP generating system was used to supply ATP. In contrast ATP degrading systems completely abolished translocation. The inner envelope mem brane localized ATP-ase is probably not involved in the transport event. The results suggest that ATP is needed at the outer chloroplast envelope. Inhibition of protein transport by A D P , pyrophosphate and NaF is studied and its con sequences discussed. | | | |
Reference
| Z. Naturforsch. 42c, 103 (1987); received August 26 1986 | | | |
Published
| 1987 | | | |
Keywords
| Protein T ransport, ATP-Hydrolysis, Chloroplasts, Envelope, Pisum sativum | | | |
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| default:Reihe_C/42/ZNC-1987-42c-0103.pdf | | | | Identifier
| ZNC-1987-42c-0103 | | | | Volume
| 42 | |
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