| | 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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| default:Reihe_C/38/ZNC-1983-38c-0951.pdf | | | | Identifier
| ZNC-1983-38c-0951 | | | | Volume
| 38 | |
| 4 | Author
| Henri Brunner, Manfred Muschiol, Wilfried Nowak | Requires cookie* | | | Title
| Optisch aktive Übergangsmetall-Komplexe, LVII [1] | | | | Abstract
| (+)-und (—)-C5H5M(CO)(P02R*)X mit M = Fe, "Fe und X = 1, COCH3, CH3 Optically Active Transition Metal Complexes, LVII [1] (+)-and (—)-C5H5M(CO)(P02R*)X with M = Fe, "Fe, and X = I, COCH3, CH3 In the reaction of C5H5Fe(CO)2l and CsHsFefCO^CHa, respectively, with S-(+)-(C6H5)2PN(CH3)CH(CH3)(C6H5) (abbreviated P02R*) the complexes C5H5Fe(CO)(P02R*)I(l),C5H5Fe(CO)(P02R*)COCH3(2),andC5H5Fe(CO)(P02R !,t)CH3(3) are formed as pairs of diastereoisomers the components of which differ only in the configu-ration at the iron atom. CsH5Fe(CO)(P02R*)CH3 (3) can be obtained in higher yield by photochemical decarbonylation of C5H5Fe(CO)(P02R*)COCH3 (2). The (+)s85-and (—)365-diastereoisomers of each pair exhibit different chemical shifts in the X H NMR spectra. Diastereoisomer separation can be achieved by fractional crystallization. Starting with 57 Fe metal (—)365-C5H5 57 Fe(CO)(P02R*)I was prepared via 57 FeI2, 57 Fe(CO)4l2, C5H5 57 Fe(CO)2l, and C5H5 57 Fe(CO)(P02R*)I in order to demonstrate optical activity of a 57 Fe compound in the y region by Mössbauer polarimetry in later experiments to be reported elsewhere. | | | |
Reference
| Z. Naturforsch. 33b, 407—411 (1978); eingegangen am 24. Januar 1978 | | | |
Published
| 1978 | | | |
Keywords
| Diastereoisomer Separation, X H NMR, Optical Activity, Transition Metal Complexes | | | |
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| default:Reihe_B/33/ZNB-1978-33b-0407.pdf | | | | Identifier
| ZNB-1978-33b-0407 | | | | Volume
| 33 | |
| 6 | Author
| Henri Brunner, Heinz Vogt | Requires cookie* | | | Title
| Optically Active Transition Metal Complexes, LIX [1] | | | | Abstract
| The pair of diastereoisomers (+)436-and (—)436-C5H5Fe(CO)(COCH3)P02R*, with P02R* = (S)-(+)-(C6H5)2PN(CH3)CH(CH3)(C6H5), can be separated into its components by preparative liquid chromatography under pressure. On heating (+)436-C5H5Fe(CO)-(COCH3)P02R* equilibrates with C5H5Fe(CO)2CH3 and P02R* before epimerization at the Fe [atom takes place. In the same way, the equilibrium C5H5Fe(CO)(COCH3)P(C6Hs)3 C5H5Fe(CO)2CH3 + P(C6Hs)3 can be obtained starting from either side. It is shown that the decarbonylation C5H5Fe(CO)(COCH3)P(C6H5)3 C5H5Fe(CO)(CH3)P(C6H5)3 + CO is not a thermal but a photochemical reaction. | | | |
Reference
| Z. Naturforsch. 33b, 1231—234 (1978); eingegangen am 6. Juli 1978 | | | |
Published
| 1978 | | | |
Keywords
| Diastereoisomer Separation, Preparative Liquid Chromatography, 1 H NMR, Optical Activity, Transition Metal Complexes | | | |
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| default:Reihe_B/33/ZNB-1978-33b-1231.pdf | | | | Identifier
| ZNB-1978-33b-1231 | | | | Volume
| 33 | |
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