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1978 (2)
1Author    Wilhelm Menke, Friederike Koenig, GeorgH. Schmid, Alfons RadunzRequires cookie*
 Title    Functional Characterization of Four Thylakoid Membrane Polypeptides with Apparent Molecular Weights between 40 000 and 48 000  
 Abstract    Four polypeptides which exhibited apparent molecular weights from 40 000 to 48 000 were isolated from the thylakoid membrane. The isolation was achieved by gel filtration of polypeptides, solubilized by means of sodium dodecyl sulfate and, after removal of detergent by anion exchange chromatography in ethanolic solution. The polypeptide of the molecular weight 40000 was iden­ tified as the 7-component of the coupling factor of photophosphorylation via the effect of its 
  Reference    Z. Naturforsch. 33c, 280 (1978); received February 27 1978 
  Published    1978 
  Keywords    Thylakoid Membrane Polypeptides, Antisera, Photosynthesis 
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 TEI-XML for    default:Reihe_C/33/ZNC-1978-33c-0280.pdf 
 Identifier    ZNC-1978-33c-0280 
 Volume    33 
2Author    Friederike Koenig, Alfons Radunz, GeorgH. Schmid, Wilhelm MenkeRequires cookie*
 Title    Antisera to the Coupling Factor of Photophosphorylation and Its Subunits  
 Abstract    Stroma-freed chloroplasts were extracted with sucrose palmitate-stearate containing buffer. A fter the addition o f dodecyl sulfate and mercaptoethanol to the extract a series of polypeptides was isolated from the mixture by gel filtration. These polypeptides were later used for immunization. Antisera to four polypeptides reacted in the Ouchterlony double diffusion test with authentic coupling factor yielding a precipitation band. According to the observed apparent molecular weights the polypeptides are the a, ß , 8 and e subunits of the coupling factor. An antiserum to the y subunit has been obtained already previously. A ll antisera inhibit photophosphorylation reactions and electron transport considerably. Addition of gramicidin inhibits photophosphorylation com pletely whereas gramicidin restores electron transport in the assays with the antisera to the a, ß , y and 5 subunit. In the case o f the antiserum to the E subunit gramicidin does not regenerate electron transport. As in the presence of the serum to the £ subunit pH changes in the suspension medium are not observed, this serum seems to open a proton channel. Also, upon addition of dicyclohexyl carbodiimide (D C C D) pH changes in the suspension medium in the assay with antiserum do not reoccur. According to these unexpected results the identity o f the antigen with the e subunit of the coupling factor is not certain. ATP-ase reactions are only inhibited by the antisera to the a and y subunit and what is thought to be the £ subunit. The antiserum to the a subunit uncouples electron transport as the only one when used in sufficient concentrations. The dosis-effect curves o f the inhibition of the electron transport exhibits a maximum. The dosis-effect curves for the other components rise after a lag phase in an approxim ately hyperbolic manner. The inhibitory action on electron transport is exerted by all antisera in the region of the reaction center I or in its immediate vicinity. This is thought to be due to the fact that a protein of the reation center I is inhibited in its function by the increasing proton concentration inside the thylakoid. The inhibition of electron transport by the antiserum to the e subunit is considered to be a direct serum effect. Besides the increase in fluorescence yield, due to the inhibition of electron transport in the region o f photosystem I, decreases of the fluorescence yield are observed in the presence of D CM U, which do not depend on the redox state of Q but rather on the condition of the thylakoid mem­ brane. Moreover, the antisera affect in a differing manner the energy spill-over o f excitation from photosystem I I to photosystem I. 
  Reference    Z. Naturforsch. 33c, 529 (1978); received June 21 1978 
  Published    1978 
  Keywords    Coupling Factor, Antisera, Chloroplasts, Fluorescence 
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 TEI-XML for    default:Reihe_C/33/ZNC-1978-33c-0529.pdf 
 Identifier    ZNC-1978-33c-0529 
 Volume    33