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1990 (1)
1983 (1)
1982 (1)
1Author    Bernhard HuchzermeyerRequires cookie*
 Title    Energy Transfer Inhibition Induced by Nitrofen  
 Abstract    The herbicide nitrofen was shown to act as an energy transfer inhibitor. The results proved nitrofen to act by inhibiting nucleotide exchange on the chloroplast coupling factor. A strong correlation was found between the inhibition o f phosphorylation, ATPase activity, and nucleotide exchange. These results are discussed in terms of a regulatory effect o f tightly bound A D P on the enzymatic activity o f the chloroplast coupling factor. 
  Reference    Z. Naturforsch. 37c, 787—792 (1982); received April 30/June 8 1982 
  Published    1982 
  Keywords    Herbicides, Nitrofen, Energy Transfer Inhibition, Photophosphorylation, N ucleotide Exchange 
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 TEI-XML for    default:Reihe_C/37/ZNC-1982-37c-0787.pdf 
 Identifier    ZNC-1982-37c-0787 
 Volume    37 
2Author    G. O., G. S. Chäfer, H. S. Tro, Tm AnRequires cookie*
 Title    Synthesis of 2'-/3'-0-Acylated Adenine Nucleotide Analogs and Their Interactions in Photophosphorylation  
 Abstract    By mono esterification o f 3'(2')-hydroxyl residues o f adenine nucleotides with various carb-oxylic acids a series o f nucleotide analogs is available including fluorescent and photoaffinity labels. Their chemical synthesis is described. The equilibrium between 2' and 3' esters is determined by N M R spectroscopy, stability o f the esters and their tendency o f acyl migration is discussed. The interaction o f the A D P derivatives with the chloroplast ATP synthesizing system is in­ vestigated. Actually, the analogs are typical energy transfer inhibitors, strongly inhibiting photo­ phosphorylation and concom itant coupled electron transport (ci50 values ranging from 0.3 to 85 |iM). On the basis o f inhibitory activities o f analogs bearing varying 3'-(2')-substituents, struc-ture-activity relationships are discussed. The inhibitory properties o f the em ployed A D P analogs are based on their specific interaction with the catalytic AD P binding site o f CF] and their extrem ely slow phosphorylation on the enzyme (rate 0.25% or less com pared to A D P phosphorylation). Inhibition is com petitive to AD P but non-com petitive with regard to P; . It is specific for the A D P derivatives, whereas the corresponding ATP analogs are only weak inhibitors in phosphorylation and the AMP derivatives are com pletely inactive. In light-triggered ATP hydrolysis, however, the ATP analogs exhibit an even stronger com petitive inhibition than the A D P derivatives. The results suggest that a conformational change o f ATPase takes place when the chloroplasts are transferred from energized to de-energized conditions which greatly affects the properties o f the active site with respect to nucleotide binding. In tro d u c tio n 
  Reference    Z. Naturforsch. 38c, 49 (1983); received October 7 1982 
  Published    1983 
  Keywords    N ucleotide Analogs, Photophosphorylation, Energy Transfer Inhibition 
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 TEI-XML for    default:Reihe_C/38/ZNC-1983-38c-0049.pdf 
 Identifier    ZNC-1983-38c-0049 
 Volume    38 
3Author    Bernhard Huchzermeyer, Andreas LöhrRequires cookie*
 Title    Diphenyl Ether Herbicides, a Tool to Elucidate the Mechanism of Photophosphorylation  
 Abstract    At least two different classes of A DP binding sites on chloroplast coupling factor are de­ scribed in the literature. High-affinity sites are assumed to entail regulatory functions while low-affinity sites are involved in catalysis. Diphenyl ether herbicides, acting as energy transfer inhibitors, interfere with nucleotide ex­ change on both categories of A D P binding sites. Their inhibitory potency varies depending on their substitution. We found that each diphenyl ether assayed revealed identical / 50 values for inhibition of nucleotide interaction with both classes of binding sites. We show here that diphenyl ether inhibition of energytransfer is primary based upon the interference with A DP binding to high-affinity binding sites. Thereby the control of proton permeability through the coupling factor complex is affected. Moreover, we found that the three ß-subunits are not absolutely fixed in one conformational state: After covalently block­ ing the high-affinity site by an azido-label, a new ß-subunit. 
  Reference    Z. Naturforsch. 45c, 552—557 (1990); received October 10 1989 
  Published    1990 
  Keywords    Diphenyl Ethers, Energy-Transfer Inhibition, Nitrofen, Photophosphorylation, Coupling Factor 
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 TEI-XML for    default:Reihe_C/45/ZNC-1990-45c-0552.pdf 
 Identifier    ZNC-1990-45c-0552 
 Volume    45