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1993 (1)
1992 (1)
1Author    M. J. Melo, Fernando Pina, A. Ntónio, L. M. Açanita, EuricoC. Melo, Christiane Herrm, R. Olf Förster, HelmUt Koch, Heinrich WamhoffRequires cookie*
 Title    Photochemistry of 2-(2-Furyl)-benzimidazole (Fuberidazole)  
 Abstract    The photodegradation o f 2-(2-Furyl)-benzim idazole (Fuberidazole 1) has been reinvestigat­ ed employing advanced H P L C -U V /V IS technique and fluorescence emission and excitation spectroscopy in methanol at natural pH , in acidic medium and in aqueous solutions at pH 7 and 3, and four main products benzim idazole-2-carboxylic acid 3, its methyl ester 2, 1-methoxy benzimidazole 5, methyl 4-oxo-2-benzim idazole crotonate 7 (cis and trans isomers) besides benzimidazole 4 and 2,2'-bibenzimidazole 6 and other side products have been isolated and characterized. The kinetics o f the photodegradation process was followed independently by H P L C -U V and fluorescence emission showing a significant similarity o f the curve habit; this allows to m onitor a photodegradation at very low concentrations (5 -10-5—5 -10-6 M). The quantum yield o f disappearance o f Fuberidazole has been determined. 
  Reference    Z. Naturforsch. 47b, 1431—1437 (1992); received April 6 1992 
  Published    1992 
  Keywords    2-(2-Furyl)-benzimidazole, Fuberidazole, Photodegradation, HPLC Separation, Fluorescence Emission 
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 TEI-XML for    default:Reihe_B/47/ZNB-1992-47b-1431.pdf 
 Identifier    ZNB-1992-47b-1431 
 Volume    47 
2Author    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