Go toArchive
Browse byFacets
Bookbag ( 0 )
'Inhibitors' in keywords Facet   section ZfN Section C:Volume 034  [X]
Results  5 Items
Sorted by   
Publication Year
1979 (5)
1Author    ArminH. Ildebrandt, Rudolf Mengel, HelmutW. SauerRequires cookie*
 Title    Characterization of an Endogenous Transcription Inhibitor from Physarum polycephalum  
 Abstract    A substance has been purified from isolated nuclei of Physarum polycephalum by equilibrium and velocity gradient centrifugations, ion exchange chromatography and gel filtration which has a high molecular weight, can be labeled in vivo with 32P, is heat stable and resistant to amylases, proteases, nucleases and phosphodiesterase but is sensitive to phosphatases or hydrolysis. This material consists of phospate and glycerol. It selectively inhibits in vitro transcription of RNA polymerases, predominantly the homologous enzyme A by binding to the enzyme. In the presence of this inhibitor of transcription a stable RNA polymerase-template complex cannot be formed. Binding to and inactivation of RNA polymerase is reversible at high ionic strength. 
  Reference    Z. Naturforsch. 34c, 76 (1979); received July 3/ November 21 1978 
  Published    1979 
  Keywords    RNA polymerases, Inhibitor, Glycerophosphate, Physarum 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_C/34/ZNC-1979-34c-0076.pdf 
 Identifier    ZNC-1979-34c-0076 
 Volume    34 
2Author    W. Alter OettmeierRequires cookie*
 Title    Quantitative Structure Activity Relationship of Diphenylamines as Inhibitors of Photosynthetic Electron Transport and Photophosphorylation  
 Abstract    A number of 16 substituted diphenylamines have been tested for their inhibitory activity on photosynthetic NADP reduction and photophosphorylation. The most active compounds exhibited p l50 values of 6.0 in photosynthetic electron transport and 6.8 in cyclic photophosphorylation, respectively. The inhibition site in electron flow of the diphenylamines is located between the two photosystems. Necessary for high activity is the substitution of the phenyl moieties by several strongly electron withdrawing substituents. A quantitative structure activity relationship according to a parabolic Hansch approach could be accomplished by using the Hammett electronic parameter as the only variable. 
  Reference    Z. Naturforsch. 34c, 1024—1027 (1979); received May 31 1979 
  Published    1979 
  Keywords    Diphenylamines, Inhibitors, Photosynthetic Electron Transport 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_C/34/ZNC-1979-34c-1024.pdf 
 Identifier    ZNC-1979-34c-1024 
 Volume    34 
3Author    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 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_C/34/ZNC-1979-34c-0831.pdf 
 Identifier    ZNC-1979-34c-0831 
 Volume    34 
4Author    Klaus Pfister, CharlesJ. ArntzenRequires cookie*
 Title    The Mode of Action of Photosystem II-Specific Inhibitors in Herbicide-Resistant Weed Biotypes  
 Abstract    This report reviews studies which provide evidence defining the mode of action and site of action of photosystem II (PS II) herbicides; the involvement of the secondary electron carrier on the reducing side of PS II (called B) is indicated as the target site for these compounds. These studies of the action of PS II-inhibitors were perform ed in chloroplasts of various weed species in order to define the mechanism which is responsible for herbicide tolerance at the level of chloroplast mem branes in newly discovered triazine-resistant weed biotypes. M any species of triazine-resistant weed biotypes have been collected in N orth America and Europe. W here data is available, these plants have been found to share the following common fe atu res: a) they were discovered in areas where triazine herbicides had been used repeatedly, b) resistance to the triazines is extrem e; it is not due to a m inor shift in herbicidal response, c) no changes in herbicide uptake, translocation or metabolism — as compared to susceptible bio­ types — can be detected, d) resistance is selective for only certain classes of photosynthetic herbicides, and, e) chloroplasts isolated from triazine-resistant weeds display high preferential resistance to the triazines in assays of photosystem II partial reactions. To focus on the mechanism which regulates preferential herbicide activity, we have characterized susceptible and resistant chloroplasts in the presence and absence of herbicides. Properties of the PS II complex of chloroplasts from several different triazine-resistant weed biotypes share the fol­ lowing tr a its : a) the herbicide binding site (as measured by direct binding of radiolabeled herbicides or by in­ hibition experiments) is modified such that the affinity for triazines is dram atically reduced. b) alterations in response to many PS II-herbicides occur such th at the triazine-resistant chloro­ plasts are very strongly resistant to all sym m etrical triazines, strongly resistant to assymmetrical triazinones, partially resistant to pyridazones and uracils, only slightly resistant to ureas or amides, and increasingly susceptible to nitrophenols, phenols and the herbicide bentazon (all as compared to susceptible chloroplasts), c) there is a change in the reaction kinetics of the electron transport step between the prim ary and secondary electron acceptors (referred to as Q and B), and d) in two examples, specific small changes in a m em brane polypeptide can be detected in the resistant thylakoids. We suggest that certain amino acids or segments of the apoprotein of B (the bound quinone which acts as the secondary electron carrier) are modified or deleted in these chloroplasts. Such a polypeptide change could affect both the redox poising of the Q~/B reaction pair, and the specific binding of herbicides. 
  Reference    Z. Naturforsch. 34c, 996—1009 (1979); received June 29 1979 
  Published    1979 
  Keywords    Herbicide, Resistance, Photosynthesis, Electron Transport, Inhibitors 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_C/34/ZNC-1979-34c-0996.pdf 
 Identifier    ZNC-1979-34c-0996 
 Volume    34 
5Author    Friedrich JüttnerRequires cookie*
 Title    The Algal Excretion Product, Geranylacetone: A Potent Inhibitor of Carotene Biosynthesis in Synechococcus  
 Abstract    The algal excretion product geranylacetone was proved to be an effective and novel inhibitor of carotene synthesis in Synechoccus 6911. The application of geranylacetone resulted in an ac­ cumulation of phytofluene, indicating an inhibition of the conversion of this compound into f-carotene. The cts-isomer of geranylacetone was as effective as the natural irans-isomer. The chloro­ phyll synthesis was only slightly affected. 
  Reference    Z. Naturforsch. 34c, 957 (1979); received June 16 1979 
  Published    1979 
  Keywords    Geranylacetone, Cyanobacteria, Synechococcus, Algal Excretion Product, Inhibitor, Carotene Bio­ synthesis 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_C/34/ZNC-1979-34c-0957.pdf 
 Identifier    ZNC-1979-34c-0957 
 Volume    34