[Comparative studies on the lipid composition of etioplasts and chloroplasts from Pisum and of chloroplasts from an Aurea mutant of Nicotiana].
Etioplasts and chloroplasts isolated from Pisum sativum differ in lipid composition. The relative amounts of galactolipids, especially of MGD, are higher in the chloroplast. In contrast, the sulfo- and the phospholipids are already present in the etioplasts in higher concentrations. During the formation of the thylakoids with stacked membranes only the galactolipids are synthesized simultaneously with the pigments. It is suggested that the polar lipids are embedded into the membranes after the basic structure has already been formed.A different type of membrane formation has been described for the chloroplasts of an aurea mutant of tobacco.The grana formation was observed when the plants were grown under lower light intensities. The possibility of a parallel synthesis of polar lipids and pigments is discussed on the basis of the lipid analysis. However, the amount of MGD is lower in the chloroplasts with a higher degree of stacking. The low temperature absorbance spectrum is identical in chloroplasts from yellow and green leaves. Since the mutant is lacking in chlorophyll b, the conclusion can be drawn that this pigment and MGD are not involved in the contact of the grana stacks. From the analysis of lipids released from the membranes under hypotonic conditions, it is concluded that MGD is localized at the surface.
Lehrstuhl für Biochemie der Pflanze der Universität, Untere Karspüle 2, D-3400, Göttingen, Bundesrepublik Deutschland.
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Heise
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Jacobi