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'Phytochrome' in keywords Facet   Publication Year 1979  [X]
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1Author    Hugo Scheer, Helmut Formanek, W. Olfhart RüdigerRequires cookie*
 Title    The Conformation of Bilin Chromophores in Biliproteins: Ramachandran-Type Calculations  
 Abstract    Ramachandran-type calculations are perform ed for conformations o f bilin chromophores pres­ ent in the biliproteins phycocyanin, phycoerythrin and phytochrome. The atom ic coordinates are taken from x-ray data o f crystalline model compounds, namely biliverdin for pyrrole rings B, C, D and substituted succinimides for the hydrogenated ring A including a thioether containing ^-sub­ stituent. Maxima and m inim a for steric hindrance are calculated for rotation o f the thioether side chain, the rotation of pyrrole rings at single bonds (syn-anti-forms) and at double bonds (Z-E-iso-mers) of the methine bridges. Whereas quasi-planar structures are possible for all syn, Z-forms, only twisted structures are possible if anti, E-forms are considered. The relevance for the bilin con­ formations of native biliproteins and o f the Pr ^ Pfr phototransform ation is discussed. 
  Reference    Z. Naturforsch. 34c, 1085 (1979); received June 29 1979 
  Published    1979 
  Keywords    Bilin Conformation, Phycocyanin, Phycoerythrin, Phytochrome 
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 TEI-XML for    default:Reihe_C/34/ZNC-1979-34c-1085.pdf 
 Identifier    ZNC-1979-34c-1085 
 Volume    34 
2Author    W. Kufer, H. ScheerRequires cookie*
 Title    Chemical Modification of Biliprotein Chromophores  
 Abstract    The reaction of biliproteins with sodium dithionite has been studied. The reagent is selective towards the chromophores. In denatured phycocyanin from Spirulina platensis, all three chromo­ phores react to form yellow "phycorubin", whereas only 1 /3 of the chromophores react in native phycocyanin in a non-statistical manner. From reversion experiments, it can be shown, that the thermodynamic stability of the chromophores towards reaction with dithionite is increased in the native pigment. Similarly, native phytochrome in its P r form reacts only partially to a pigment ab­ sorbing at both 420 and 660 nm. The same product is formed from native Pfr, indicating both a reversion to Pr and a partial reduction. 
  Reference    Z. Naturforsch. 34c, 776—781 (1979); received July 2 1979 
  Published    1979 
  Keywords    Biliproteins, Phycocyanin, Phytochrome, Chromophore Modification, Dithionite, Reversible De­ naturation 
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 TEI-XML for    default:Reihe_C/34/ZNC-1979-34c-0776.pdf 
 Identifier    ZNC-1979-34c-0776 
 Volume    34