ZfN: Search Results

1	Author	C. Schamagl, E. Köst-Reyes, S. Schneider, H.-P Köst, H. Scheer	Requires cookie*
	Title	Circular Dichroism of Chromopeptides from Phycocyanin
	Abstract	The circular dichroism of bilipeptides from Spirulina geitleri phycocyanin is strongly solvent and pH dependent. Maximum optical activity has been observed in aqueous solutions containing urea (8 M). In aqueous buffer, a sign reversal occurred upon the change from neutral to acidic pH; in methanolic solutions shows the optical activity a strong pH dependence both with respect to sign and magnitude. These findings have been rationalized by the presence o f chrom ophore-peptide interactions, which are minim ized in the presence of urea. M olecular orbital calculations indicate that the observed sign reversal is not necessarily due to a reversal o f the chirality o f the entire chromophore, but may also result from more localized conform ational changes.
	Reference	Z. Naturforsch. 38c, 951—959 (1983); received June 22 1983
	Published	1983
	Keywords	Biliproteins, Bilipeptides, Conform ation, Optical Activity, Protein Interaction
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	TEI-XML for	default:Reihe_C/38/ZNC-1983-38c-0951.pdf
	Identifier	ZNC-1983-38c-0951
	Volume	38

2	Author	W. Kufer, H. Scheer	Requires 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

3	Author	P. Hefferle, P. Geiselhart, T. Mindl, S. Schneider, W. John, H. Scheer	Requires cookie*
	Title	Time-Resolved Polarized Fluorescence of C-Phycocyanin and Its Subunits from Mastigocladus laminosus
	Abstract	The influence o f aggregation and temperature on the excited state kinetics o f C -phycocyanin from Mastiqocladus laminosus has been studied. Polarized fluorescence decay curves have been recorded using a synchronously pum ped dye laser in conjunction with a synchroscan streak camera. The experimental data for all sam ples can be fit satisfactorily assum ing a biexponential decay law. Fluorescence depolarization tim es have been interpreted in terms o f energy transfer among the different chromophores. The influence o f temperature is only m oderate on the intra molecular relaxation, but pronounced on the rates o f energy transfer. Both are dependent on the size o f the aggregate. The biexponential decay o f the a-subunit containing only one Chromo phore, indicates the presence o f different subsets o f chrom ophores in these sam ples. The results are discussed in terms o f variations o f the chrom ophore arrangem ents upon temperature induced changes in the protein conformation.
	Reference	Z. Naturforsch. 39c, 606 (1984); received February 16 1984
	Published	1984
	Keywords	Photosynthesis, Biliproteins, Picosecond Spectroscopy, Energy Transfer, Protein D enaturation
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	TEI-XML for	default:Reihe_C/39/ZNC-1984-39c-0606.pdf
	Identifier	ZNC-1984-39c-0606
	Volume	39