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1993 (2)
1984 (1)
1Author    JohnL. Huppatz, JohnN. PhillipsRequires cookie*
 Title    Cyanoacrylate Inhibitors of the Hill Reaction III. Stereochemical and Electronic Aspects of Inhibitor Binding  
 Abstract    Ethoxyethyl 3-octylamino-2-cyanoacrylate and related com pounds in which the am ino group was replaced by N -C H 3, S, O and CH 2 were synthesized and their activity as inhibitors o f the Hill reaction in isolated pea chloroplasts determ ined. All com pounds show ed m oderate to high activity but there was no obvious correlation between activity and the electronic character o f the ester carbonyl group. The stereochemistry o f the various inhibitor m olecules was deduced from the PMR spectra and the possible influence o f stereochem istry on Hill inhibitory activity discussed. Replacement o f the olefinic proton in the 2-cyanoacrylates with a /?-alkyl substituent was examined and a specific relationship between the length o f the alkyl chain and activity was observed. 
  Reference    Z. Naturforsch. 39c, 617 (1984); received D ecem ber 28 1983 
  Published    1984 
  Keywords    Cyanoacrylates, Inhibitors o f Electron Transport, Hill Reaction, Stereochemistry 
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 TEI-XML for    default:Reihe_C/39/ZNC-1984-39c-0617.pdf 
 Identifier    ZNC-1984-39c-0617 
 Volume    39 
2Author    WendyK. Banham, JohnL., -.H., H. IllipRequires cookie*
 Title    N-Methylanilinocyanoacrylate Photosystem II Inhibitors. Structure-Activity Relationships  
 Abstract    Many 3-N-methylanilino cyanoacrylate derivatives are potent inhibitors o f photosynthetic electron transport at the PS II level in a thylakoid system isolated from Pisum sativum. These inhibitors are somewhat unusual in that they take more than 15 min to equilibrate with the binding site in contrast to most classical PS II inhibitors which tend to equilibrate rapidly i.e. within the mixing time o f seconds. The effects o f m ono-and disubstituents in the aryl nucleus on inhibitory activity were studied. The nature and position o f the substituent had no detectable influence on equilibration rate but a pronounced influence on inhibitory activity as measured by equilibrium p/ 50 values. Substituent position enhanced inhibitory activity in the order 3 ' > 2 ' » > 4 ' . As regards the nature o f the substituent, size appeared to be the most important parameter -the smaller the substituent the greater the activity. Such influences were in contrast to those in analogous 3-anilino-and 3-benzylamino-2-cyano-acrylate series where the com ­ parable order o f substituent position effect was 3' and 4' » 2 ' and where substituent hydro-phobicity rather than size was the most important factor. Disubstituted fluoro derivatives have given interesting insights into the preferred orientation o f these inhibitors at the binding site with the 2'-and 5'-positions interacting positively, the 4'-position, negatively, and the 3'-position neutrally. 
  Reference    Z. Naturforsch. 48c, 136 (1993); received December 3 1992 
  Published    1993 
  Keywords    Cyanoacrylates, Photosystem II Inhibitors, Structure Activity 
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 TEI-XML for    default:Reihe_C/48/ZNC-1993-48c-0136.pdf 
 Identifier    ZNC-1993-48c-0136 
 Volume    48 
3Author    JohnN. Phillips, WendyK. BanhamRequires cookie*
 Title    Hydrogen Bonding of Cyanoacrylates with the D 1 Peptide  
 Abstract    Representatives o f two structural types o f cyanoacrylate PS II inhibitors have been studied in respect to their p/ 50 values and qualitative rate o f binding with wild type and S 2 6 4 G mutant thylakoids isolated from Brassica napus. Both are potent inhibitors o f photosynthetic electron transport and both show a large discrimination between wild type and mutant thylakoids under equilibrium conditions. However one, an N-m ethylanilino cyanoacrylate, has an initial rapid reaction with both wild type and mutant thylakoids, but continues to react slowly with the wild type species until equilibrium is reached, while the other, a benzylamino cyanoacry­ late, equilibrates rapidly with both species as does the classical PS II inhibitor, atrazine. These differences in kinetic behaviour have been interpreted in terms o f different H-bond interac­ tions with the serine-264 hydroxyl group. It is suggested that the slow binding reaction is due to the N -m ethylanilino com pound interacting as an H-bond acceptor with the serine-264 hy­ droxyl hydrogen thus disrupting an intramolecular ser-264-his-252 H-bond within the D 1 peptide. Rapid equilibration on the other hand, has been attributed to the benzylam ino deriva­ tive acting as an H-bond donor to the serine-264 hydroxyl oxygen and strengthening the 2 6 4 -2 5 2 H -bond by conjugation. It is proposed that atrazine and other classical PS II inhibi­ tors act in this way and that this may explain their ability to inhibit trypsin degradation o f the D 1 peptide, if the 2 6 4 -2 5 2 intramolecular H-bond plays an important role in stabilizing the peptide conform ation. It is also speculated that photodegradation may be related to the ability o f Q b~ to act as an H-bond acceptor and disrupt the 2 6 4 -2 5 2 H-bond. 
  Reference    Z. Naturforsch. 48c, 132 (1993); received N ovem ber 16 1992 
  Published    1993 
  Keywords    Brassica napus, Cyanoacrylates, D 1 Peptide, H -Bonding, Photodegradation 
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 TEI-XML for    default:Reihe_C/48/ZNC-1993-48c-0132.pdf 
 Identifier    ZNC-1993-48c-0132 
 Volume    48