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1Author    W.Requires cookie*
 Title    Circulardichroismusuntersuchungen des Thyreotropin-Releasinghormons (TRH) Circular Dichroism Investigations of TRH  
 Abstract    o l f g a n g V o e l t e r , K a r l Z e c h , P e t e r G ö b e l , O s k a r O s t e r u n d A n t o n io A t t a n a s io Im Zusammenhang mit Untersuchungen zur Struktur13 und Wirkungsweise4 der kürzlich aufge­ klärten5-6 Hypothalamus-Releasinghormone haben wir Circulardichroismus(CD)-Spektren des Thyreo­ tropin-Releasinghormons (TRH) vermessen, da mit der Methode des CD konformative und konfi­ gurative Änderungen optisch aktiver Moleküle nachweisbar sind. TRH wird durch Kuppeln der Aminosäurederi­ vate Benzyloxycarbonyl-(4.4'-dimethoxybenzhy-dryl)-L-glutamin, L-Histidin-methylester und l -Prolinamid mit N.N'-Dicyclohexylcarbodiimid dar­ gestellt3. Die Primärstruktur von TRH ist Pyr-His-Pro-NH2. 
  Reference    (Z. Naturforsch. 30b, 142—143 [1975]; eingegangen am 15. September 1973) 
  Published    1975 
  Keywords    Circular Dichroism, Releasing Hormones, Peptides 
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 TEI-XML for    default:Reihe_B/30/ZNB-1975-30b-0142_n.pdf 
 Identifier    ZNB-1975-30b-0142_n 
 Volume    30 
2Author    Hartmut Vergin, Hermann Bauer, Gisela Kuhfittig, Wolfgang VoelterRequires cookie*
 Title    Investigations on the Configuration of 4-Nitro Imidazole Nucleosides  
 Abstract    It is demonstrated that the 220 — 225 nm Cotton effect of 4-nitro imidazole nucleosides can be used for the determination of the configuration of this class of compounds. A more detailed picture about conformation and configuration of the sugar residue is received from the copper-ammonia complexes of these nucleosides. The pH-dependency of the stability and the complex ratio are discussed for a furanose moiety. Correlation between signs and intensities of the Cotton effects and configurations and conforma-tions of the diol structures are discussed. 
  Reference    (Z. Naturforsch. 27b, 1378—1385 [1972]; eingegangen am 2. Juni/7. August 1972) 
  Published    1972 
  Keywords    Nucleosides, Circular Dichroism, Nuclear Magnetic Resonance, Carbohydrate Copper Complexes 
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 TEI-XML for    default:Reihe_B/27/ZNB-1972-27b-1378.pdf 
 Identifier    ZNB-1972-27b-1378 
 Volume    27 
3Author    Mohammed Khalid, FarnazM. Khan3, M. Alikb, Shahnaz Ashooda Hasanb, G. Perveen3, Ünther Snatzke, WolfgangV. OelterRequires cookie*
 Title    Circular Dichroism Studies on Chiral l,3?4,5-Tetrahydro-2//-l,5- benzodiazepin-2-ones  
 Abstract    From forty one chiral benzodiazepin-2-ones the U V and CD data are reported and the bands discussed with respect to corresponding electronic transitions respectively stereochem ­ ical features. 
  Reference    Z. Naturforsch. 50b, 1869—1882 (1995); received May 4 1995 
  Published    1995 
  Keywords    Circular Dichroism, Benzodiazepines, Chiral Benzodiazepin-2-ones 
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 TEI-XML for    default:Reihe_B/50/ZNB-1995-50b-1869.pdf 
 Identifier    ZNB-1995-50b-1869 
 Volume    50 
4Author    Seym Our, Steven Brody, R. Ichard, P. F. GregoryRequires cookie*
 Title    Effect of Hydrogen Ion Concentration on the Absorption Spectrum and Fluorescence Life Time of Chloroplasts  
 Abstract    Subjecting pea chloroplasts to hydrogen ion gradients results in small but significant changes in the absorption and circular dichroic spectra. The relative intensities o f the fast and slow fluorescence decays are modified by the hydrogen ion concentration. The life time of the slow components is only slightly altered. At pH 11 the circular dichroic peak at 690 nm, assigned to Photosystem I chlorophyll-protein complex, is clearly resolved. Also, there is a splitting o f the peak at 6 5 0 -6 4 0 nm, attributed to Photosystem II chlorophyll-protein. At pH 3.9 splitting o f the 6 5 0 -6 4 0 nm peak is observed. There is also a positive component at 705 nm which may be associated with an aggregated form of chlorophyll or pheophytin. The changes in absorption spectra are determined by measuring the difference in spectra between identical chloroplasts suspensions one at pH 7.6 and the other at alkaline or acidic pH. At pH 2 and pH 3.7 there are time dependent increases in absorbance at 430, 445, 520, 538, 670 nm, and a decrease in absorbance at 606 nm. After a delay o f 11 min at pH 2, there is also an increase in absorbance at 700 nm. The latter is interpreted as possible formation o f aggregated pheophytin. At pH 11.0 there are time dependent increases in absorbance at 638, 454 and 440 nm, and decreases in absorbance at 675, 660, 508 and 472 nm. The changes in absorbance of the pigment around 520 nm (associated with an electrochromic effect) is interpreted as resulting from a leakage o f hydrogen ion across the thylakoid membrane. The spectral changes that occur during the first 9 min are reversible. After the chloroplasts have incubated for more than 15 min most of the spectral changes are not reversible. 
  Reference    Z. Naturforsch. 36c, 638 (1981); received March 13 1981 
  Published    1981 
  Keywords    Photosynthesis, Chlorophyll, Chloroplasts, Fluorescence Life Time, Circular Dichroism 
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 TEI-XML for    default:Reihe_C/36/ZNC-1981-36c-0638.pdf 
 Identifier    ZNC-1981-36c-0638 
 Volume    36 
5Author    Wolfgang Zacharias, H. Artm, Ut FollmRequires cookie*
 Title    Irregularities in the Circular Dichroism of Oligoribonucleotides  
  Reference    Z. Naturforsch. 37c, 727—730 (1982); received February 26/April 211982 
  Published    1982 
  Keywords    Oligoadenylic Acids, Oligouridylic Acids, Conform ation, Circular Dichroism 
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 TEI-XML for    default:Reihe_C/37/ZNC-1982-37c-0727_n.pdf 
 Identifier    ZNC-1982-37c-0727_n 
 Volume    37 
6Author    JanuszVladimír Blasiaka, Zofia Kleinwächterb, RenataŽ. Walter3, AludovábRequires cookie*
 Title    Interaction of Organophosphorus Insecticide Methylparathion with Calf Thymus D N A and a Synthetic D N A Duplex  
 Abstract    The interaction of an organophosphorus insecticide m ethylparathion (O.O-dimethyl 0-4-nitrophenyl phosphorothioate) with double-stranded DNA was characterized by UV and circular dichroism (CD) spectroscopy. Two kinds of DNA were employed: calf thymus DNA (CT DNA) and a synthetic two-stranded oligomer of sequence 5'-d(TTG GA TCCG AA TT-C A A G CTT)-3\ Melting curves and CD spectra were taken for the DNAs in the presence of the insecticide at methylparathion/DNA base pair molar ratio of 0.5. The insecticide evoked a decrease of the melting tem perature and a broadening of the transition range for CT DNA. Similar effects were observed for the synthetic oligomer but they were less pronounced than in the case of CT DNA. M ethylparathion evoked a slight shift and an increase in the ampli­ tude of the negative band in the CD spectra of both DNAs. O btained results indicate that methylparathion may perturb the thermal stability and conformation of DNA, which is an evidence that the insecticide has an ability to interact directly with DNA. 
  Reference    Z. Naturforsch. 50c, 820—823 (1995); received August 8/Septem ber 19. 1995 
  Published    1995 
  Keywords    DNA, Methylparathion, Melting Curves, Circular Dichroism, Pesticides 
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 TEI-XML for    default:Reihe_C/50/ZNC-1995-50c-0820.pdf 
 Identifier    ZNC-1995-50c-0820 
 Volume    50 
7Author    IgorZ. Zubrzycki3, Lothar BohmbRequires cookie*
 Title    Folding of the SPKK Rich Peptide in the Presence of the Octa-Oligonucleotide  
 Abstract    The nucleosom e contains o f 200 base pairs of D N A com plexed with four core histone complex: H 2A , H2B, H3, and H4. The fifth histone species, the HI histone, interacts with linker D N A connecting neighbouring nucleosomes. We have studied the influence o f the phosphorylation on the interactions of a repeating unit 15 residues long, containing the SPKK motif, the m otif thought to induce turn along peptides sequences, enclosed within the trout testis H I C-terminal domain with octanucleotide by means of the thermal denaturation and CD technique. The results indicate that the peptide preferentially binds to a single stranded oligonucleotide. It has been shown further that there is no ß structure present but a distorted helical structure has been detected. 
  Reference    Z. Naturforsch. 52c, 77—8 (1997); received March 11/August 19 1996 
  Published    1997 
  Keywords    N ucleosom e, Histone, Circular Dichroism, Thermal Denaturation 
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 TEI-XML for    default:Reihe_C/52/ZNC-1997-52c-0077.pdf 
 Identifier    ZNC-1997-52c-0077 
 Volume    52 
8Author    J. Fleischhauer, A. Koslowski, Ch Repges, K.-R Gulden, G. BringmannRequires cookie*
 Title    The Absolute Configuration of Isoancistrocladine and 'Isohamatine' by Quantumchemical CD-Calculations  
 Abstract    The absolute configuration of the naphthylisoquinolines isoancistrocladine and isohamatine at the biaryl axis was determined by comparing the measured and the calculated CD spectra. In order to calculate these spectra we used the CNDO/S method in combination with a Boltzmann weighting of conformers with different dihedral angles at the biaryl axis. The Boltzmann factors were obtained with the AM 1 method. 
  Reference    Z. Naturforsch. 53a, 993—996 (1998); received November 3 1998 
  Published    1998 
  Keywords    Circular Dichroism, Biaryls, CNDO/S Method, AMI Method 
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 TEI-XML for    default:Reihe_A/53/ZNA-1998-53a-0993.pdf 
 Identifier    ZNA-1998-53a-0993 
 Volume    53 
9Author    Luis Moroder5, Roberta Romano3, Elisabeth Weyhera, Michal Svobodab, Jean ChristophebRequires cookie*
 Title    Circular Dichroism Study on Fully Bioactive CCK-Peptides of Increasing Chain Length  
 Abstract    A C D conformational analysis has been performed on CCK-peptides elongated at the N-terminus in sequence mode beyond the naturally occurring CCK-8 up to the pentadecapep-tide sequence. By extending N-terminally the CCK-8 sequence an intramolecular salt bridge between the tyrosine-O-sulfate and the arginine guanido function is allowed to be established. However, this intramolecular electrostatic interaction was not found to affect the bioactivities o f the CCK-peptides indicating that induction o f such salt bridge at the level o f the ligand molecule does not prevent a similar interaction at receptor level by exchange o f the counterion partner. As expected for unconstrained short linear peptides the dichroic properties in aqueous solution were indicative o f predominantly random coil structure. Conversely, in aqueous TFE the C D spectra were consistent with the presence o f y-type turns similarly to what has been observed under identical conditions for small size peptides related to the hom ologuous gastrin hormone. In surfactant solutions the CCK-peptides were found to assume /?-type structures by inserting at least the C-terminal portion o f the bioactive core into more hydrophobic compart­ ments o f the surfactant micelles, whereas the hydrophilic charged N-termini o f the CCK -pep­ tides o f increasing chain length are exposed to the water phase in random coil structures as suggested by the CD spectra. This contrasts previous findings related to the hom ologuous gas­ trin peptides, where identical CD spectra were recorded in aqueous TFE and in presence o f micelles. This observation strongly suggests that gastrin and CCK related peptides exhibit dis­ tinct conformational preferences, despite their high degree o f sequence hom ology, and fully agrees with the ability o f CCK to interact specifically with different receptors. 
  Reference    Z. Naturforsch. 48b, 1419—1430 (1993); received July 13 1993 
  Published    1993 
  Keywords    CCK-Peptides, Structure-Function Relationship, Bioactivities, Circular Dichroism, Lipid Interaction 
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 TEI-XML for    default:Reihe_B/48/ZNB-1993-48b-1419.pdf 
 Identifier    ZNB-1993-48b-1419 
 Volume    48 
10Author    MichaelS. Clegg, DieterW. GruenwedelRequires cookie*
 Title    Circular Dichroism and Ultraviolet Absorbance of Calf Thymus D NA in Presence of C H 3HgOH  
 Abstract    The changes that one observes upon the addition of CH3HgOH in the circular dichroism spec­ trum and ultraviolet absorbance spectrum of native calf thymus DNA, dissolved in buffered (pH 6.8) solutions of Na2S04 at pNa 2.0, 1.5, 1.0, and 0.0, respectively (p N a = —log [Na+ ]), are shown to be due to denaturation brought about by the organomercurial interacting with the base moieties of the polymer. The changes are characterized by an extensive shift of both spectra to longer wavelengths, by a decrease of the rotational strength of the long-wavelength positive dichroic absorption band, and by an increase in the UV absorbance at l max • Both the hyperchromicity H * of calf thymus DNA and the normalized decrease of the rotational strength of its long-wavelength positive dichromic band, Q , display cooperativity when plotted against the methylmercury concentra­ tion pM (p M = — log [CH3HgOH] a dde d) at a given salt strength. Rotational strength data, eval­ uated by integration of the area under the positive and negative dichroic absorption bands, have been tabulated for selected values of pNa and pM. They are compared with data available from the literature. In absence of CH3HgOH, and with varying salt strength, native calf thymus DNA exhibits alterations in the long-wavelength positive dichroic absorption band that are interpreted as representing B — * ■ C transitions in agreement with currently held views regarding their origin. Similar salt-induced alterations have been noted in the case of denatured DNA; their meaning in terms of DNA geometry remains unclear at this point in time. 
  Reference    Z. Naturforsch. 34c, 259—265 (1979); received November 27 1978 
  Published    1979 
  Keywords    Circular Dichroism, Ultraviolet Absorbance, Calf Thymus DNA, Methylmercury Complexes, Denaturation 
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 TEI-XML for    default:Reihe_C/34/ZNC-1979-34c-0259.pdf 
 Identifier    ZNC-1979-34c-0259 
 Volume    34 
11Author    G. M. Bonora, F. Bertanzon, V. Moretto, C. TonioloRequires cookie*
 Title    Protamines. VII. Circular Dichroism Study of Salmine A I  
 Abstract    Salmine A I, one of the components of the protamine from salmon, has been purified and characterized. The conformational preferences o f salmine A I have been examined as a function o f pH, added salts, presence o f helix-supporting solvents, and temperature, using circular dichroism. It has been found that this small basic protein adopts predominantly an unordered conformation in aqueous solution. Addition of counter-ions, in particular perchlorate, and 2-chloroethanol induces to various extents the onset of the right-handed a-helical conformation. The results are discussed in comparison with those previously reported on the three main components of clupeine, the protamine from herring, and with the published conformational predictions by various statistical methods. 
  Reference    Z. Naturforsch. 36c, 305—309 (1981); received October 161980 
  Published    1981 
  Keywords    Protamine, Salmine, Circular Dichroism, a-Helix, Secondary Structure Prediction 
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 TEI-XML for    default:Reihe_C/36/ZNC-1981-36c-0305.pdf 
 Identifier    ZNC-1981-36c-0305 
 Volume    36 
12Author    Johann Sonnenbichler, Ifeanyi Madubunyi, Hugo ScheerRequires cookie*
 Title    Stereochemistry of Two Hydroxybiflavanonols from Garcinia cola Nuts  
 Abstract    The absolute configuration of two hydroxybiflavanonols from Garcinia cola nuts have been determ ined by CD and 500 MHz 'H NMR spectroscopy. A dditionally the occurrence of atrop-isomers at room tem perature as the consequence of rotational hindrance in the molecules could be dem onstrated. 
  Reference    Z. Naturforsch. 42c, 855 (1987); received March 30/May 18 1987 
  Published    1987 
  Keywords    Biflavanonol, Stereochem istry, A tropisom er, 'H NMR, Circular Dichroism 
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 TEI-XML for    default:Reihe_C/42/ZNC-1987-42c-0855.pdf 
 Identifier    ZNC-1987-42c-0855 
 Volume    42 
13Author    J. Schmidt, H. Gottstein, Scheer, A. ScherzRequires cookie*
 Abstract    Micellar aggregates have been prepared from chloro­ phyll a. Whereas most detergents including non-ionic, zwitterionic and anionic ones, produce aggregates with long-wavelength shifted and enhanced Q Y absorption, the cationic detergents hexadecyl-trimethylammonium-bromide and hexadecyl-pyridiniumchloride produce complexes with opposite traits: The Q Y absorption is shifted to shorter wavelengths, and it is hypochromic. The optical activity is increased as in the long-wave­ length shifted complexes, but the cd bands are non-con­ servative and coincide with the absorption maxima. The complexes are most likely small aggregates o f chloro­ phyll with a changed geometry as compared to the "standard" ones. 
  Reference    Z. Naturforsch. 45c, 729—732 (1990); received January 26 1990 
  Published    1990 
  Keywords    Chlorophyll, Micelles, Detergent, Aggregation, Absorp­ tion, Circular Dichroism, Molecular Orbital 
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 TEI-XML for    default:Reihe_C/45/ZNC-1990-45c-0729_n.pdf 
 Identifier    ZNC-1990-45c-0729_n 
 Volume    45 
14Author    SeungR. Yong, D. Ieter, W. G. Ruenw EdelRequires cookie*
 Title    Differential Effect of Hg(II) on [d(A)n * d(T)n] and [d(A-T)n * d(A-T)n] Sequences: Circular Dichroism (CD) Measurements and Endonuclease Digestion Studies Using Poly|d(A) * d(T)] and Poly[d(A-T) * d(A-T)] as Substrates  
 Abstract    The long-wavelength positive CD bands o f poly[d(A) • d(T)] and poly[d(A-T)-d(A-T)] be­ come inverted upon the addition of Hg(C104)2. Poly[d(A)-d(T)] requires higher levels of mer­ cury to undergo inversion than poly[d(A-T)-d(A-T)]\ Mercurated poly[d(A) d(T)] is digested more rapidly than the control by DNase I or staphylococcal nuclease at low levels of Hg(C104)2. Let r = [Hg(C104)2]added/[DNA-P]. A 4-to 5-fold rate increase occurs with DNase I at r = 0.25; a 2-fold increase with staphylococcal nuclease at r = 0.2. By contrast, digestion of poly[d(A-T) d(A-T)] decreases immediately with increasing r. The noted rate increases appear to be due to a modification of poly[d(A)-d(T)] helix structure prior to the chiroptical conver­ sion. The modification is interpreted as a widening of the minor groove, permitting, thus, a better binding of DNase I to its substrate. The overall changes in CD as well as enzymatic digestion rates are taken to signal mercury-induced alterations in helix screwness from right-to-left. They are totally reversible subsequent to the removal o f mercury. 
  Reference    Z. Naturforsch. 48c, 488—494 (1993); received September 18 1992/February 2 1993 
  Published    1993 
  Keywords    Circular Dichroism, Endonucleases, Polynucleotides, Mercury Complexes, Right«-*Left Inversions 
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 TEI-XML for    default:Reihe_C/48/ZNC-1993-48c-0488.pdf 
 Identifier    ZNC-1993-48c-0488 
 Volume    48 
15Author    PaavoH. Hynninen, Gunnel SieversRequires cookie*
 Title    Conformations of Chlorophylls a and a' and their Magnesium-Free Derivatives as Revealed by Circular Dichroism and Proton Magnetic Resonance  
 Abstract    The electronic absorption (UV/VIS), circular dichroism (CD) and proton magnetic resonance (*H NMR) spectra have been recorded for C-l0 epimeric chlorophylls a and a', pheophytins a and a' as well as pheophorbides a and a'. Although the epimers in each pair showed virtually identical UV/VIS spectra, their CD spectra were profoundly different and exhibited opposite signs at most wavelengths in the UV region. The differences were interpreted as arising, in part, from different C-10 configurations, and, in part, from conformational alterations induced by the steric strain in the crowded periphery of the macrocycle. The conformational alterations were also clearly indicated by the X H NMR zJö-values observed for the a,ß and <5 methine protons, the C-10 protons and most methyl group protons of the epimers in each pair. This was considered to imply changes in the geometry of the whole macrocycle. The A 6-values were larger for the Mg-free epimers than for the chlorophyll epimers, which shows that the central Mg-atom makes the macrocycle more rigid. Correlations between the signs of the CD bands and configurations are discussed. 
  Reference    Z. Naturforsch. 36b, 1000—1009 (1981); received May 19 1981 
  Published    1981 
  Keywords    Stereochemistry, Conformational Analysis, Chlorophyll and Pheophytin Epimers, X H NMR Spectra, Circular Dichroism 
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 TEI-XML for    default:Reihe_B/36/ZNB-1981-36b-1000.pdf 
 Identifier    ZNB-1981-36b-1000 
 Volume    36 
16Author    Corrado Paolinelli3, M. Ario Barterib, Federico Boffi3, Francesca Forastieri3, Maria Cristina, G. Audianob, StefanoDella Longac, AgostinaCongiu Castellano3Requires cookie*
 Title    Structural Differences of Ovalbumin and S-Ovalbumin Revealed by Denaturing Conditions  
 Abstract    We found, by circular dichroism and Raman spectroscopy measurements, that the second­ ary structure of the native ovalbumin and of its heat-stable form, called S-ovalbumin, is a probe of the structural differences between the two proteins. Small angle X-ray scattering and circular dichroism measurem ents perform ed on the two proteins under denaturing condi­ tions, with different concentrations of guanidine hydrochloride, show the changes of the tertiary and secondary structure and a different pathway in the unfolding process. These experimental data confirm that the conversion of native ovalbumin into S-ovalbumin is irreversible and reveal that the response of the two proteins to the same chemical environ­ ment is different. 
  Reference    Z. Naturforsch. 52c, 645—653 (1997); received February 10/June 20 1997 
  Published    1997 
  Keywords    X-Ray Scattering, Conformational Changes, Protein Folding, Synchrotron Radiation, Circular Dichroism, Protein Structure 
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 TEI-XML for    default:Reihe_C/52/ZNC-1997-52c-0645.pdf 
 Identifier    ZNC-1997-52c-0645 
 Volume    52