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1988 (1)
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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. Küfer, H. ScheerRequires cookie*
 Title    Rubins and Rubinoid Addition Products from Phycocyanin  
 Abstract    The verdin-type Chromophore o f denatured C-phycocyanin (1) from Spirulina platensis is reduced to the corresponding rubin (2 a) by sodium borohydride. The structure assigned is in agreement with the uv-vis spectroscopic properties of the product and was deduced from model studies with free bile pigments. Analogous model studies using sodium dithionite demonstrated a two-fold reactivity for this reagent, leading to products which are both o f the rubin spectral type under the conditions tested. True rubins (10,22-dihydrobilindions) are formed in low yield only if an excess o f reagent is used in methanol/water mixtures. It is accompanied by polar addition product(s) o f the same spectral type, which are generally formed exclusively. In particular, no bilirubin was formed under the reaction conditions previously applied for the chemical modification o f phycobiliproteins and phytochrome. From this finding and from the strikingly different properties o f the borohydride and dithionite products, o f phycocyanin upon renaturation, the dithionite product is suggested to be a rubinoid addition product (2 b) rather than a hydrogenation product. In contrast to the dithionite addition product 2 b of phycocyanin, the chromophore o f the true phycorubin (2 a) remains stable upon renaturation. The uv-vis spectral properties of the chromophore are not markedly different whether the apoprotein is in its native or denatured state. The different electrophoretic mobilities o f native (renatured) phycocyanin compared to the renatured borohydride product suggest that these two have different protein conformations. The preparation of these phycorubins renders the extensive techniques o f bilirubin chemistry applicable in the study o f biliproteins. 
  Reference    Z. Naturforsch. 37c, 179—192 (1982); received December 151981 
  Published    1982 
  Keywords    Phycocyanin, Phycorubin, Bile Pigments, Biliverdin, Bilirubin 
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 TEI-XML for    default:Reihe_C/37/ZNC-1982-37c-0179.pdf 
 Identifier    ZNC-1982-37c-0179 
 Volume    37 
3Author    Harald Lehner, Hugo ScheerRequires cookie*
 Title    Circulardichroism of C-Phycocyanin: Origin of Optical Activity in Denatured Biliproteins and Evidence for an Intermediate during Unfolding  
 Abstract    The circulardichroism spectra (cd) o f native and (partially) urea-denaturated C-phycocyanin (PC) in the spectral range 7 0 0 -2 1 0 nm are presented. The large ellipticities observed in the chrom ophoric region of native PC are retained in the fully denatured state (8 M urea). This is sim ilar to the behavior of the red form of phytochrome (Pc), but in contrast to C-phycoerythrin (PE). These differences are rationalized in terms of epim eric equilibria betw een P-and M-helix shaped chromophores. D epending on the num ber and location o f the chirality centers present in the tetrapyrrol moities a priori, the excess populations of the inherently chiral P-and M-helices differ, thus accounting for large (PC, Pr) or small (PE) ellipticities in the denatured pigments. Hence, the large optical activity observed for the form er is generated by an excess population of the P-helix induced by the asymmetric C-2, C-3 and C-3'. In PE the additional chirality center at C -l6 counteracts the influence of the others. The excess population o f the inherently chiral species is therefore lowered, in agreem ent with the nearly vanishing cd reported for denatured PE. The cd has also been studied at interm ediate urea concentrations. U nfolding of PC with urea can be interpreted from these data as a stepwise process. M onitoring the urea induced unfolding of PC by cd at different wavelengths (A = 220, 345, and 610 nm); the "melting po in t" o f the apoprotein (4 -5 M urea) coincides with the extrema of the titration curves obtained in the chrom ophore region (345, 610 nm). These results give direct evidence for the existence of an interm ediate species whose population reaches a m aximum at 4 — 5 M urea. 
  Reference    Z. Naturforsch. 38c, 353 (1983); received January 17 1983 
  Published    1983 
  Keywords    Phycocyanin, Phycoerythrin, Phytochrom, C irculardichroism, D enaturation 
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 TEI-XML for    default:Reihe_C/38/ZNC-1983-38c-0353.pdf 
 Identifier    ZNC-1983-38c-0353 
 Volume    38 
4Author    HainfriedE A Schenk, M. Argarete, Neu-M ÜllerRequires cookie*
 Title    Der Einfluß von Cycloheximid und Chloramphenicol auf die Biosynthese der Photosynthese-Pigmente in Cyanophora paradoxa Korsch I. Photosynthetische Sauerstoffproduktion Photosynthetic O xygen Evolution  
 Abstract    The Influence o f C yclohexim ide and C hloram phenicol on the B iosynthesis o f the Photosynthetic P igm ents in Cyanophora paradoxa I. It is not clear whether an endocytobiont is able to develop during a long evolution tim e only to an organelle like cell structure (defect m utant) with a high degree of m etabolic dependency or also to a perfect cell organelle with genetical dependency to the host nucleus (intercom partm ental translocation of proteins an d /o r gene transfer) in the sense of the Serial Endocytobiosis Hypothesis (SEH). Cyanocyta korschokoffiana, the endocyanelle of C. paradoxa, seems to be a very suitable object to answer this question. Therefore we have studied the influence o f the translation inhibitors cycloheximide (CHI) and chloramphenicol (CA) on the biosynthetic behaviour of this cyanobacterial endocytobiont regarding the photosynthetic oxygen during 20 h developing and incubation time. After dilution with fresh culture m edium the oxygen evolution of the control culture remains nearly constant, if it is related to the phycocyanin content, whereas it increases slowly to a constant level relating to the chlorophyll content (nearly 140-150% o f the starting activity). CHI and CA show a rapid effect on the oxygen evolution. At the first 8 -10 h the oxygen evolution of cultures treated with CA are hardly dim inished and rem ain m ore or less constant with regard to the starting activity, but that of cultures treated with CHI decreases strongly. After 24 h the CHI treated flagellate is photosynthetically inactive and far-reaching destroyed (microscopic observations), indicating that CHI has beside the inhibition effects on protein synthesis also secondary effects on the stability o f m em branes o f C. paradoxa. Der apochlorotische Flagellat Cyanophora 
  Reference    Z. Naturforsch. 38c, 978—983 (1983); received July 19 1983 
  Published    1983 
  Keywords    Cyanophora paradoxa, Photosynthetic Activity, Oxygen Evolution, Chlorophyll, Phycocyanin 
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 TEI-XML for    default:Reihe_C/38/ZNC-1983-38c-0978.pdf 
 Identifier    ZNC-1983-38c-0978 
 Volume    38 
5Author    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 
6Author    M. Argarete, N. Eu-, M. Üller, H. Ainfried, E. A. SchenkRequires cookie*
 Title    Der Einfluß von Cycloheximid und Chloramphenicol auf die Biosynthese der Photosynthese-Pigmente in Cyanophora paradoxa Korsch. HI. Chlorophyll a und Phycochromoproteide Chlorophyll a and Phycochrom oproteids  
 Abstract    The Influence o f Cyclohexim ide and C hloram phenicol on the B iosynthesis o f the P hotosynthetic P igm ents in Cyanophora paradoxa. III. The inhibition effects o f CHI and CA on the biosynthesis o f the tetrapyrrolpigments were measured with two methods (in vivo VIS-spectroscopy, for chlorophyll (Chi) and the phyco­ chromoproteids, 14C incorporation only for Chi). In the case o f the Chl-biosynthesis both methods show the sam e results: a) In vivo VIS-spectroscopy demonstrates that the inhibition effect o f CA manifests faster than that o f CHI, b) during the 14C incorporation into Chi chloramphenicol (CA) inhibits more than cyclohexim ide (CHI) in contrary to the behaviour o f chloroplasts. It seems that the CHI caused decrease o f l4C incorporation into Chi can be ascribed to the decreased photosynthesis. The influence o f the antibiotics o f the phycochrom o­ proteids is similar to that observed for chlorophyll. It is remarkable that under the influence o f CHI the phycochromoproteid biosynthesis is significantly better than under CA influence, although CHI damages the consortium more than CA. That can be interpreted, as for chlorophyll, with a more endocytobiont coded phycochrom oproteid synthesis. 
  Reference    Z. Naturforsch. 38c, 990—9 (1983); received July 19 1983 
  Published    1983 
  Keywords    Cyanophora paradoxa, Biosynthesis, Chlorophyll, Phycocyanin, Allophycocyanin, C yclohexim ide, Chloramphenicol 
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 TEI-XML for    default:Reihe_C/38/ZNC-1983-38c-0990.pdf 
 Identifier    ZNC-1983-38c-0990 
 Volume    38 
7Author    Hugo Scheer, Hartmut KayserRequires cookie*
 Title    Conformational Studies of Biliproteins from the Insects Pieris brassicae and Cerura vinula  
 Abstract    Chromophore conformation and protein secondary structure of biliproteins from the butterfly, Pieris brassicae, and the moth, Cerura vinula, have been investigated by absorption, circular dichroism and fluorescence spectroscopy. The chromophore of the P. brassicae protein, biliverdin IXy, has probably a cyclic-helical structure similar to that of free bile pigments of the biliverdin type. Though achiral by structure the chromophore displays strong optical activity in the native protein-bound state, but becomes inactive after urea denaturation of the protein. A minor bilipro-tein from P. brassicae shows absorption, circular dichroism and fluorescence spectra identical to the main biliprotein. In the biliprotein from Cerura vinula the structure of the pigment is still unknown. It has a semi-open conformation intermediate between that of the Pieris proteins and that of the phycobiliprotein, C-phycocyanin, and it retains optical activity after urea denaturation. The band widths and the size of the Stokes shifts of the fluorescence spectra indicate a high degree of conformational flexibility of the chromophores in the two Pieris pigments, and a decreased flexibility in the one from Cerura. In the biliproteins from both insects the polypeptides are low in a-helix content compared to that of phycobiliproteins. From these and earlier data, insect and algal biliproteins seem to be related only distantly if at all, but there exist also considerable differences among insect biliproteins from different species. 
  Reference    Z. Naturforsch. 43c, 84—90 (1988); received August 26 1987 
  Published    1988 
  Keywords    Biliverdin IXy, Chromophore Conformation, Phycocyanin, Pieris brassicae, Cerura vinula 
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 TEI-XML for    default:Reihe_C/43/ZNC-1988-43c-0084.pdf 
 Identifier    ZNC-1988-43c-0084 
 Volume    43