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  • 1
    Electronic Resource
    Electronic Resource
    Structure Effects of Double D-Amino Acid Replacements: A Nuclear Magnetic Resonance and Circular Dichroism Study Using Amphipathic Model Helixes (1995)
    s.l. : American Chemical Society
    Biochemistry 34 (1995), S. 12954-12962 
    Details
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/bi00040a005
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  • 2
    Electronic Resource
    Electronic Resource
    Comparison of the solution structures of microcystin-LR and motuporin (1995)
    [s.l.] : Nature Publishing Group
    Nature structural biology 2 (1995), S. 114-116 
    Details
    ISSN: 1072-8368
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Medicine
    Notes: [Auszug] Sir — Microcystin and nodularin cyclic peptide hepatotoxins are cyanobacterial metabolites found worldwide in freshwater and marine environments1. These toxins are responsible for wildlife fatalities and adverse human health effects in countries where drinking water supplies contain ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nsb0295-114
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  • 3
    Electronic Resource
    Electronic Resource
    Temperature coefficients of amide proton NMR resonance frequencies in trifluoroethanol: A monitor of intramolecular hydrogen bonds in helical peptides? (1996)
    Springer
    Journal of biomolecular NMR 8 (1996), S. 93-97 
    Details
    ISSN: 1573-5001
    Keywords: 1H NMR ; Amide-proton chemical shifts ; Helix ; Temperature shift ; Mixed solvents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary 2D 1H NMR spectroscopy of two α-helical peptides which differ in their amphipathicity has been used to investigate the relationships between amide-proton chemical shifts, amide-proton exchange rates, temperature, and trifluoroethanol (TFE) concentration. In 50% TFE, in which the peptides are maximally helical, the amide-proton chemical shift and temperature coefficient patterns are very similar to each other in each peptide. Temperature coefficients from −10 to −6 ppb/K, usually indicative of the lack of intramolecular hydrogen bonds, were observed even for hydrophobic amino acids in the center of the α-helices. However, slow hydrogen isotope exchange for residues from 4 to 16 in both 18-mer helices indicates intact intramolecular hydrogen bonds over most of the length of these peptides. Based on these anomalous observations, we suggest that the pattern of amide-proton shifts in α-helices in H2O/TFE solvents is dominated by bifurcated intermolecular hydrogen-bond formation between the backbone carbonyl groups and TFE. The amide-proton chemical shift changes with increasing temperature may be interpreted by a disruption of intermolecular hydrogen bonds between carbonyl groups and the TFE in TFE/water rather than by the length of intramolecular hydrogen bonds in α-helices.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00198143
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  • 4
    Electronic Resource
    Electronic Resource
    On choosing a detergent for solution NMR studies of membrane proteins (1998)
    Springer
    Journal of biomolecular NMR 11 (1998), S. 381-386 
    Details
    ISSN: 1573-5001
    Keywords: detergents ; membrane proteins ; micelles ; mixed micelles ; translational diffusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Translational diffusion coefficients and catalytic activities were measured for the integral membrane protein diacylglycerol kinase (DAGK) in a variety of types of detergent micelles. Despite the structural diversity of the detergents examined, the translational diffusion coefficients observed for DAGK spanned a fairly limited range of values: 2.7 to 4.7 (× 10-7cm2/s). No general correlation was observed between the diffusion coefficients for the detergent-DAGK aggregates and the sizes of the corresponding protein-free micelles. These results indicate that the effective molecular weights of the DAGK-detergent aggregates were determined more by the structural properties of the protein than by the properties of the detergents. The catalytic activity of DAGK in detergents having medium-length alkyl chains such as dodecylphosphocholine or decylmaltoside was usually observed to be substantially higher than in short-chain detergents such as octylphosphocholine or octylglucoside. Taken together, the diffusion and activity results indicate that medium-chain detergents are generally preferred for use in NMR studies of complex membrane proteins because they are no worse than short-chained detergents in terms of increasing the effective molecular weight of the protein of interest while they are considerably better at maintaining native-like protein conformation. Among the 10 detergents examined, only sodium dodecylsulfate was observed to be unable to support DAGK activity under any conditions examined, suggesting that this well-known protein denaturant should be used with care in studies of complex membrane proteins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008289624496
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  • 5
    Electronic Resource
    Electronic Resource
    ORB, a homology-based program for the prediction of protein NMR chemical shifts (1997)
    Springer
    Journal of biomolecular NMR 10 (1997), S. 165-179 
    Details
    ISSN: 1573-5001
    Keywords: Automated sequential assignment ; Homology-based protein NMR chemical shift prediction; ; Protein NMR chemical shift databases ; Multiple alignment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A computer program (ORB) has been developed to predict 1H,13C and 15N NMR chemical shifts of previouslyunassigned proteins. The program makes use of the information contained in achemical shift database of previously assigned proteins supplemented by astatistically derived averaged chemical shift database in which the shifts arecategorized according to their residue, atom and secondary structure type[Wishart et al. (1991) J. Mol. Biol., 222, 311–333]. The predictionprocess starts with a multiple alignment of all previously assigned proteinswith the unassigned query protein. ORB uses the sequence and secondarystructure alignment program XALIGN for this task [Wishart et al. (1994)CABIOS, 10, 121–132; 687–688]. The prediction algorithm in ORB isbased on a scoring of the known shifts for each sequence. The scores dependon global sequence similarity, local sequence similarity, structuralsimilarity and residue similarity and determine how much weight one particularshift is given in the prediction process. In situations where no applicablepreviously assigned chemical shifts are available, the shifts derived from theaveraged database are used. In addition to supplying the user with predictedchemical shifts, ORB calculates a confidence value for every prediction. Theseconfidence values enable the user to judge which predictions are the mostaccurate and they are particularly useful when ORB is incorporated into acomplete autoassignment package. The usefulness of ORB was tested on threemedium-sized proteins: an interleukin-8 analog, a troponin C synthetic peptideheterodimer and cardiac troponin C. Excellent results are obtained if ORB isable to use the chemical shifts of at least one highly homologous sequence.ORB performs well as long as the sequence identity between proteins with knownchemical shifts and the new sequence is not less than 30%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018389332160
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  • 6
    Electronic Resource
    Electronic Resource
    CAMRA: Chemical shift based computer aided protein NMR assignments (1998)
    Springer
    Journal of biomolecular NMR 12 (1998), S. 395-405 
    Details
    ISSN: 1573-5001
    Keywords: assignment homology programs ; automatic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A suite of programs called CAMRA (Computer Aided Magnetic Resonance Assignment) has been developed for computer assisted residue-specific assignments of proteins. CAMRA consists of three units: ORB, CAPTURE and PROCESS. ORB predicts NMR chemical shifts for unassigned proteins using a chemical shift database of previously assigned homologous proteins supplemented by a statistically derived chemical shift database in which the shifts are categorized according to their residue, atom and secondary structure type. CAPTURE generates a list of valid peaks from NMR spectra by filtering out noise peaks and other artifacts and then separating the derived peak list into distinct spin systems. PROCESS combines the chemical shift predictions from ORB with the spin systems identified by CAPTURE to obtain residue specific assignments. PROCESS ranks the top choices for an assignment along with scores and confidence values. In contrast to other auto-assignment programs, CAMRA does not use any connectivity information but instead is based solely on matching predicted shifts with observed spin systems. As such, CAMRA represents a new and unique approach for the assignment of protein NMR spectra. CAMRA will be particularly useful in conjunction with other assignment methods and under special circumstances, such as the assignment of flexible regions in proteins where sufficient NOE information is generally not available. CAMRA was tested on two medium-sized proteins belonging to the chemokine family. It was found to be effective in predicting the assignment providing a database of previously assigned proteins with at least 30% sequence identity is available. CAMRA is versatile and can be used to include and evaluate heteronuclear and three-dimensional experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008321629308
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  • 7
    Electronic Resource
    Electronic Resource
    Assignment of the helical structure in neuropeptide Y by HPLC studies of methionine replacement analogues and 1H-NMR spectroscopy (1996)
    New York : Wiley-Blackwell
    Biopolymers 39 (1996), S. 207-219 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The HPLC retention behavior of three complete single methionine and methionine sulfoxide replacement sets of two 18-mer model peptides and neuropeptide Y (NPY) were investigated. All peptides were prepared by multiple solid-phase peptide synthesis. Plotting the retention time differences between methionine and methionine sulfoxide analogues vs the position of replacement shows that potentially α-helical peptides become helical on binding during reversed-phase high performance liquid chromatography. In the case of an amphipathic α-helix, the retention time differences change periodically with a 3-4 repeat pattern, which allow the location of amphipathic helical structures. Replacements in nonamphipathic α-helical domains cause local preferential binding areas and lead to sequence-dependent retention time profiles. Methionine replacement studies of NPY suggest an unstructured or extended conformation from Tyr1 to Ala12 connected to a well-defined amphipathic α-helix from Pro13 to Arg35. The assignment is confirmed by comparison of nuclear Overhauser effects based two-dimensional 1H-nmr spectroscopy and utilization of the CαH shift index method in 50% trifluoroethanol/50% water. © 1996 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Synthese mittlerer und großer Ringe, XXIII. Photochemische Umlagerung von 3,6-Alkanooxepin-4,5-dicarbonsäureestern (1989)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 199-207 
    Details
    ISSN: 0009-2940
    Keywords: 3,6-Alkanooxepine-4,5-dicarboxylic esters ; Methanohydroazulene derivatives ; Photochemical rearrangement ; Tricycloalkene derivatives ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of Medium and Large Rings, XXIII. Photochemical Rearrangement of 3,6-Alkanooxepine-4,5-dicarboxylic EstersIrradiation of the 3,6-alkanooxepine-4,5-dicarboxylic esters 1a-d affords the tricyclic aldehydes 2a-d, the constitutions of which were determined by X-ray structural analysis of 2a and 2d. The disubstituted 3,6-decanooxepine 1e gives in low yield the bridged dihydrofuran 4b, whose structure was also established by X-ray analysis. Mechanistic investigations show, that the photochemical rearrangement 1 → 2 takes place via dihydrofurans 3, cyclopropane carbaldehydes 6, and cyclopentadienecarbaldehydes 7.
    Notes: Bestrahlung der 3,6-Alkanooxepin-4,5-dicarbonsäureester 1a-d liefert die tricyclischen Aldehyde 2a-d, deren Konstitutionen durch Röntgenstrukturanalyse von 2a und 2d gesichert wurden. Das analoge disubstituierte 3,6-Decanooxepin 1e führt unter anderem zum überbrückten Dihydrofuran 4b, für das ebenfalls eine Röntgenstrukturanalyse vorliegt. Mechanistische Untersuchungen zeigen, daß die Photoumlagerung 1 → 2 über Dihydrofurane 3, Cyclopropancarbaldehyde 6 und Cyclopentadiencarbaldehyde 7 verläuft.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19891220131
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  • 9
    Electronic Resource
    Electronic Resource
    Synthese mittlerer und großer Ringe, XXV: Synthese funktionalisierter trans-Hydrindane mit angularer α-Ketoestergruppe (1989)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 1969-1975 
    Details
    ISSN: 0009-2940
    Keywords: Methanohydroazulene derivatives ; trans-Hydrindanes ; Ruthenium tetroxide oxidation ; exo-Trimethylenenorbornanone formation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of Medium and Large Rings, XXV.  -  Synthesis of Functionalized trans-Hydrindanes with angular α-Ketoester GroupRuthenium tetroxide oxidation of the tricyclic methanohydroazulenes 1a and 1d gives directly the trans-hydrindanone 2b with an angular α-ketoester group. The same oxidation of the acetal 1c affords the trans-hydrindane 2a with two α-ketoester functions. 2b can be further oxidized to the angular carboxy or methoxycarbonyl derivatives 2c and 2d. With DABCO as base the hydrindanone 2b undergoes a diastereoselective intramolecular aldol addition giving the exo-trimethylenenorbornanone 4. The trans-anellation of 2-4 was established by the X-ray structural analysis of 4 and by the 13C-NMR spectra of all compounds.
    Notes: Die Rutheniumtetroxid-Oxidation der tricyclischen Methanolaydroazulene 1a und 1d liefert das trans-Hydrindanon 2b mit angularer α-Ketoestergruppe, während die gleiche Reaktion mit dem Acetal 1c zum trans-Hydrindan 2a mit zwei α-Ketoestergruppen führt. 2b kann zu 2c und 2d mit angularer Carboxy- oder Methoxycarbonylgruppe weiter oxidiert werden. Das Hydrindanon 2b geht unter dem Einfluß von DABCO eine diastereoselektive intramolekulare Aldoladdition zum exo-Trimethylennorbornanon 4 ein. Die trans-Verknüpfung von 2-4 folgt aus der Röntgenstrukturanalyse von 4 und aus den 13C-NMR-Spektren aller Verbindungen.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19891221023
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  • 10
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    Unknown
    Spin Switching with Triazolate-Strapped Ferrous Porphyrins (2019)
    American Chemical Society
    Details
    Publication Date: 2019-04-02
    Print ISSN: 0020-1669
    Electronic ISSN: 1520-510X
    Topics: Chemistry and Pharmacology
    Published by American Chemical Society
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