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  • Chemistry  (11)
  • Least-squares optimization  (2)
  • Karplus parametrization  (1)
  • 1995-1999  (11)
  • 1985-1989  (3)
  • 1965-1969
  • 1
    Electronic Resource
    Electronic Resource
    Quantitative f torsion angle analysis in Desulfovibrio vulgaris flavodoxin based on six f related 3 J couplings (1998)
    Springer
    European biophysics journal 27 (1998), S. 321-334 
    Details
    ISSN: 1432-1017
    Keywords: Key words Vicinal coupling constants ; Polypeptide φ angles ; Karplus parameters ; Least-squares optimization ; Back-calculation of coupling constants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Quantitative φ-dihedral angle determinations of non-glycine and non-proline residues in Desulfovibrio vulgaris flavodoxin are carried out on the exclusive basis of 3 J coupling constants. In total 124 3 JHNH α , 123 3 JHNC ′i , 118 3 JHNC β , 117 3 JC′ i–1Hα , 109 3 JC′ i–1C′i , and 103 3 JC′ i–1Hβ values form the experimental basis for translating J coupling data into geometry information using various combinations of Karplus parameters given in the literature. In addition, each backbone torsional angle φ is adjusted assuming different models of local geometry, either a rigid torsion, a Gaussian distribution centered at a distinct angle, or a two-site jump model. Numerical optimization is followed by a statistical significance evaluation to assess the results. It is found that experimental coupling constants of most of the residues involved in secondary structure elements agree best with those predicted from rigid local conformations. For dihedral angles in loop regions, mobility effects are not negligible, and a single torsion (Glu 42) is likely to adopt two distinct adjustments. However, α-helix conformations with –60° 〈 φ 〈 –45° give rise to an alternate solution with φ≈+170° with similar statistical significance when using the four traditionally determined proton-involved 3 J couplings. This ambiguity is efficiently avoided only when taking advantage of the complete data set comprising six available experimental 3 J coupling constants and of the degeneracy intrinsic to the Karplus relation. The optimized φ conformations are compared with reference values from the crystal structure of flavodoxin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002490050139
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  • 2
    Electronic Resource
    Electronic Resource
    Application of H(N)CA,CO-E.COSY experiments for calibrating the φ angular dependences of vicinal couplings J(C′i−1,Hi α), J(C′i−1,Ci β) and J(C′i−1,C′i) in proteins (1997)
    Springer
    Journal of biomolecular NMR 10 (1997), S. 107-118 
    Details
    ISSN: 1573-5001
    Keywords: Vicinal coupling constants ; φ Torsion angle ; Karplus parametrization ; Desulfovibrio vulgaris flavodoxin ; Isotopic labelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A triple-resonance NMR technique suitable for the determination ofcarbonyl-related couplings in polypeptide systems is introduced. Theapplication of three novel pulse sequences to uniformly13C/15N-enriched proteins yields E.COSY-likemultiplet patterns exhibiting either one of the3J(C′i−1,Hi α), 3J(C′i−1,Ci β) and3J(C′i−1,C′i)coupling constants in the indirectly detected 13C′dimension, depending on the passive spin selected. The experiments aredemonstrated with oxidized flavodoxin from Desulfovibrio vulgaris. On thebasis of the J-values measured and the backbone φ-angles derived from ahigh-resolution X-ray structure of the protein, the three associated Karplusequations were reparametrized. The root-mean-square differences between theexperimental coupling constants and those predicted by the optimized Karpluscurves are 0.41, 0.33 and 0.32 Hz for3J(C′i−1,Hi α),3J(C′i−1,Ci β) and3J(C′i−1,C′i),respectively. The results are compared with the Karplus parameters previouslypublished for the same couplings.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018355327792
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  • 3
    Electronic Resource
    Electronic Resource
    Heteronuclear relayed E.COSY applied to the determination of accurate 3J(HN,C′) and 3J(Hβ,C′) coupling constants in Desulfovibrio vulgaris flavodoxin (1996)
    Springer
    Journal of biomolecular NMR 7 (1996), S. 142-152 
    Details
    ISSN: 1573-5001
    Keywords: Multiplet simulation ; Least-squares optimization ; Spectrum fitting ; Long-range couplings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary A simple constant-time 3D heteronuclear NMR pulse sequence has been developed to quantitatively determine the heteronuclear three-bond couplings 3J(HN,C′) and 3J(Hβ,C′) in uniformly 13C-enriched proteins. The protocols for measuring accurate coupling constants are based on 1H,13C-heteronuclear relayed E.COSY [Schmidt, J.M., Ernst, R.R., Aimoto, S. and Kainosho, M. (1995) J. Biomol. NMR, 6, 95–105] in combination with numerical least-squares spectrum evaluation. Accurate coupling constants are extracted from 2D spectrum projections using 2D multiplet simulation. Confidence intervals for the obtained three-bond coupling constants are calculated from F-statistics. The three-bond couplings are relevant to the determination of ϕ and X 1 dihedral-angle conformations in the amino acid backbone and side chain. The methods are demonstrated on the recombinant 13C, 15N-doubly enriched 147-amino acid protein Desulfovibrio vulgaris flavodoxin with bound flavin mononucleotide in its oxidized form. In total, 109 3J(HN,C′) and 100 3J(Hβ,C′) coupling constants are obtained from a single spectrum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00203824
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  • 4
    Electronic Resource
    Electronic Resource
    Mass spectral studies of the carboxylic acid ionophore antibiotic griseochelin and its derivatives (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 359-363 
    Details
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electron impact (EI) mass spectra (75 eV) of the new carboxylic acid ionophore griseochelin and some of its derivatives are discussed. The mass spectral fragmentation was studied using exact mass measurements and deuterium labelling. Furthermore, the negative ion mass spectra (2-4 eV) of these compounds are compared with their EI mass spectra.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200150702
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  • 5
    Electronic Resource
    Electronic Resource
    Solanum alkaloids. 132For Part 131, see Le thi Quyen, G. Adam and K. Schreiber, Liebigs Ann. Chem. 1143 (1994). - Electron impact mass spectrometry of solanidane N-oxides (1995)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 30 (1995), S. 201-205 
    Details
    ISSN: 1076-5174
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The electron impact mass spectra of nine solanidane N-oxides show, in addition to the known typical fragmentation pattern of the solanidane moiety, the fragment ions [M - C5H9]+ and [C6H12NO]+, due to thermal Cope syn-eliminations caused by the N-oxide function and subsequent cleavage of the bonds between C(22) and C(23) and between C(20) and C(22), respectively, in the so-obtained cyclic N,N-dialkylhydroxylamines.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jms.1190300130
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  • 6
    Electronic Resource
    Electronic Resource
    Capillary gas chromatography/mass spectrometry of permethylated gibberellin glucosidesPart 24 in the series ‘Mass Spectroscopy of Natural Products’; for Part 23 see: J. Schmidt, S. Huneck, P. Franke and J. D. Connolly, Org. Mass Spectrom., in press (1987). (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 17 (1988), S. 7-13 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Fourteen permethylated gibberellin glucosides were investigated by capillary gas chromatography/mass spectrometry. The electron impact mass spectra show a characteristic fragmentation pattern which can be used in structural elucidation of gibberellin glucosides, e.g. in the determination of the site of glucosylation at the gibberellin skeleton.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200170105
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  • 7
    Electronic Resource
    Electronic Resource
    Auslegung von Zyklonabscheidern für NotentlastungssystemeVortrag von J. SCHMIDT anläßlich der GVC Jahrestagung, 17./19. Sept. 1995 in Straßburg. (1997)
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 69 (1997), S. 312-319 
    Details
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The principal dimensions of cyclone separators for emergency response systems have been optimized by determination of the gas loading capacity for geometrically similar cyclones of 290 and 1000 mm diameter. For the experiments, separators made of Plexiglas with top or bottom mounted inlet tubes, with varying feed diameters and top and exit geometries. Moreover, the properties of the liquid in the binary mixture to be removed were also changed. For scale-up the gas volume flow density in the defiecting apron should be limited. Overall the measurements have shown that the optimized equipment is equally suited for removal of aqueous, viscous, and foaming media. The flows encountered in emergency blow-down of reactors can therefore be reliably separated. Compared to the recommendations given in the literature, significantly smaller equipment is required for the same separation performance.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cite.330690307
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  • 8
    Electronic Resource
    Electronic Resource
    Praxisbezogenes Vorgehen bei der Auslegung von Sicherheitsventilen und deren Abblaseleitungen für die Durchströmung mit Gas/Dampf-Flüssigkeitsgemischen - Teil 1 (1997)
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 69 (1997), S. 776-792 
    Details
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The design of an integral safety valve- blow-off pipe system embraces the following essential steps: 1. An incident scenario must first be defined. All reasonable deviations from proper operation of plant must be considered. 2. The flow state at the entry to the safety valve must then be ascertained (one-phase or binary flow); and 3. the minimal mass flow from the plant component to be protected must be calculated. Independently thereof, it is necessary 4. to determine the mass flow density in the blow-off pipe system; it is usually related to the cross-sectional area of the valve seat. The ratio of the two quantities gives the minimum necessary blow-off cross-sectional area. 5. In the final step, the pressure drop in the feed line and the counter-pressure at the valve exit must be examined in order to assure reliable functioning of the valve also in conjunction with the pipe system. Steps 1. to 3. are considered in this article, and steps 4. and 5. will be addressed in Part 2 to be published in this journal. Appropriate recommendations and the necessary equations are given for each step. The main emphasis is placed on applicability of the calculations.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cite.330690604
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  • 9
    Electronic Resource
    Electronic Resource
    Praxisbezogenes Vorgehen bei der Auslegung von Sicherheitsventilen und deren Abblaseleitungen für die Durchstroömung mit Dampf/Flüssigkeits-Gemischen - Teil 2Dr.-Ing. J. SCHMIDT BASF AG, ZET/ES-L511, D-67056 Ludwigshafen, Dr.-Ing. F. WESTPHAL, Hoechst AG, CR&T/PT, G864, D-65926 Frankfurt. (1997)
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 69 (1997), S. 1074-1091 
    Details
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The design of an integral safety valveblow-off pipe system embraces the following essential steps: 1. An incident scenario must first be defined. All reasonable deviations from proper operation of plant must be considered. 2. The flow state at the entry to the safety valve must then be ascertained (one-phase or binary flow); and 3. the minimal mass flow from the plant component to be protected must be calculated. Independently thereof, it is necessary 4. to determine the mass flow density in the blow-off pipe system; it is usually related to the cross-sectional area of the valve seat. The ratio of the two quantities gives the minimum necessary blow-off cross-sectional area. 5. In the final step, the pressure drop in the feed line and the counter-pressure at the valve exit must be examined in order to assure reliable functioning of the valve also in conjunction with the pipe system. Steps 1. to 3. were considered in Part 1, and steps 4. and 5. are described herein. Appropriate recommendations and the necessary equations are given for each step. The main emphasis is placed on applicability of the calculations.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cite.330690805
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  • 10
    Electronic Resource
    Electronic Resource
    Turbulenter Wärmeübergang im innenbeheizten Ringspalt mit künstlicher AußenwandrauhigkeitVortrag anläßlich der GVC-Jahrestagung, 24./26. Sept. 1997 in Dresden. (1998)
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 70 (1998), S. 1412-1416 
    Details
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cite.330701111
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