Topographical organization of cytochrome b6 in the thylakoid membrane of spinach chloroplasts determined by fluorescence studies with N-cyclohexyl-N'-[4-(dimethylamino)naphthyl]carbodiimide

Biochemistry ◽  
1993 ◽  
Vol 32 (37) ◽  
pp. 9586-9591 ◽  
Author(s):  
Yudong Wang ◽  
Diana S. Beattie
Keyword(s):  
Thylakoid Membrane ◽  
Cytochrome B6 ◽  
Fluorescence Studies ◽  
Spinach Chloroplasts ◽  
Topographical Organization

The Effect of an Antiserum to Plastocyanin on Various Chloroplast Preparations

1975 ◽  
Vol 30 (3-4) ◽  
pp. 201-212 ◽  
Author(s):  
Georg Schmid ◽  
Alfons Radunz ◽  
Wilhelm Menke
Keyword(s):  
Electron Transport ◽  
Thylakoid Membrane ◽  
Electron Flow ◽  
Linear Electron ◽  
Wild Type ◽  
Lamellar System ◽  
Spinach Chloroplasts ◽  
Monospecific Antiserum ◽  
Cyclic Photophosphorylation ◽  
Aurea Mutant

Abstract A monospecific antiserum to tobacco plastocyanin agglutinates strom a-free sw ellable chloroplasts from wild type tobacco, (Nicotia na tabacum var. John William’s Broadleaf) from the tobacco aurea mutant Su/su2, (Nicotiana tabacum var. Su/su2) from Antirrhinum majus and spinach (Spi-nacia oleracea). In this condition the antiserum inhibits linear photosynthetic electron flow in tobacco and spinach chloroplasts. This inhibition of electron transport as well as the agglutination are not observed if the chloroplasts have been sonicated prior to antiserum addition. This is due to the fact that plastocyanin is removed by ultrasonication. The antiserum stimulates a number of photophosphorylation reactions in tobacco chloroplasts. This stimulation is always larger in the aurea mutant chloroplasts and in chloroplasts from yellow leaf patches of a variegated tobacco mutant (N . tabacum , var. NC95) than in the green type chloroplasts. The stimulation appears to be a consequence of the inhibition of linear electron transport. The antiserum does not affect PMS-mediated cyclic photophosphorylation in tobacco chloroplasts from the wild type whereas the reaction appears stimulated in the tobacco mutant chloroplasts. However, menadione-mediated cyclic photo­ phosphorylation is inhibited upon addition of the antiserum. The same is true for noncyclic photo­ phosphorylation coupled to electron transport in the aerobic system diaminodurene/ascorbate → methylviologen in the presence of N-tetraphenyl-p-phenylenediamine in spinach chloroplasts. If the lamellar system of Antirrhinum and spinach has lost its swellability neither agglutination nor inhibition of electron transport is observed. However, also in this state antibodies to plasto­ cyanin are specifically adsorbed onto the surface of the thylakoid membrane. This state which is characterized by a morphologically well preserved lamellar system is realized in chloroplast prepa­ rations from Antirrhinum and spinach and is termed stroma-freed, chloroplasts. In both states of the molecular structure of the thylakoid membrane, plastocyanin is located in the outer surface of the thylakoid. However, it cannot be excluded that functioning plastocyanin is also located in the interior of the thylakoid membrane.

Variable Composition of Cytochrome b6-f Particles

1976 ◽  
Vol 31 (9-10) ◽  
pp. 606-611 ◽  
Author(s):  
Hans-Joachim Lach ◽  
Peter Böger
Keyword(s):  
Cytochrome B ◽  
Thylakoid Membrane ◽  
Chemical Structure ◽  
Stoichiometric Composition ◽  
Variable Composition ◽  
Cyt B ◽  
Photosynthetic Membrane ◽  
Cytochrome B6 ◽  
Ionic Detergents

Abstract Cytochrome b6-f particles were prepared from chloroplasts of spinach and the heterokont alga Bumilleriopsis filiformis using digitonin in comparison with non-ionic detergents. The cytochrome b6-f particles are solubilized in different amounts according to chemical structure and HLB value of the detergent (see Griffin, J. Soc. Cosmet. Chem. 1, 311 [1949]). Also the ratio of the two cytochromes in the isolated particle depends on the detergent used. In case of spinach, it varies from Cyt b6: f = 1.5:1 to 4.9:1. These investigations do not strengthen the idea that a cytochrome b6-f complex with a stoichiometric composition is present in the photosynthetic membrane. Applica­tion of different detergents is a means for selective solubilization of thylakoid membrane com­ponents.

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