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'Dibromothymoquinone' in keywords
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1979 (1)
1978 (1)
1Author    R. G. Binder, B. R. SelmanRequires cookie*
 Title    Ferredoxin Catalyzed Cyclic Photophosphorylation: Reversal of Dibromothymoquinone Inhibition by N ,N ,N ',N '-T etram ethyl- /j-phenylenediamine  
 Abstract    Conditions for washed, spinach thylakoid membranes to catalyze cyclic phosphorylation using ferredoxin as the cofactor for electron transfer have been re-examined. It was found necessary to ''redox poise" the system; however, the best method to accomplish the poising seemed to be the use of a reductant (glucose-6-phosphate) and not by optimizing the rate of phosphorylation with 3-(3,4-dichlorophenyl)-1,1-dimethyl urea (DCMU). Under these conditions, ferredoxin catalyzed cyclic phosphorylation was found to be sensitive to the inhibitors antimycin A and dibromothymo­ quinone (DBM IB). The inhibition of ferredoxin catalyzed cyclic phosphorylation by DBMIB, but not by antimycin A, was completely reversed by N, N, N', N'-tetramethyl-p-phenylenediamine (TM PD). These data are taken as further support for the function of plastoquinone in ferredoxin catalyzed cyclic phosphorylation. The effect of TMPD in reversing the DBMIB inhibition is inter­ preted as the formation of a TMPD bypass on the internal side of the thylakoid membrane around the DBMIB site of inhibition. 
  Reference    Z. Naturforsch. 33c, 261—265 (1978); received November 22 1977 
  Published    1978 
  Keywords    Cyclic Phosphorylation, Chloroplasts, Ferredoxin, Dibromothymoquinone, Phenylenediamine, Photosynthesis 
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 TEI-XML for    default:Reihe_C/33/ZNC-1978-33c-0261.pdf 
 Identifier    ZNC-1978-33c-0261 
 Volume    33 
2Author    A. Trebst, S. R. Eim Er, W. Draber, H. J. KnopsRequires cookie*
 Title    The Effect of Analogues of Dibromothymoquinone and of Bromonitrothymol on Photosynthetic Electron Flow  
 Abstract    Alkyl substituted derivatives of halogenated p-benzoquinones, of halogenated /7-nitrophenols, and of 2,4-dinitrophenols were tested in the inhibition of photosynthetic electron flow in chloro­ plasts. The effect of the compounds on photoreductions by photosystem I or II, on a TMPD bypass in NADPH formation and the reversibility of the inhibition by dithiothreitol is used to distin­ guish between an inhibition site before or after plastoquinone function, i. e. between a DBMIB versus a DCMU inhibition pattern. It is shown, that different isopropyl and /-butyl substituted halogenated p-benzoquinones are as effective and specific as DBMIB in the inhibition of plastoquinone function. Alkyl substituted /^-nitrophenols, with an additional halogen-or nitro-group at C-2, are shown to be effective electron flow inhibitors. The new potent nitrophenol derivatives inhibit at the site of DCMU action, nevertheless they do not contain the basic chemical element essential for inhibi­ tion common to DCMU and its many herbicidal analogues. Small changes in the ring-substitution can alter the inhibition pattern from a DCMU typ to a DBMIB typ inhibition. 
  Reference    Z. Naturforsch. 34c, 831 (1979); received June 1 1979 
  Published    1979 
  Keywords    Photosynthesis, Inhibitors, Herbicides, Dibromothymoquinone, Nitrophenols, Chloroplast 
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 TEI-XML for    default:Reihe_C/34/ZNC-1979-34c-0831.pdf 
 Identifier    ZNC-1979-34c-0831 
 Volume    34