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  • 1
    Electronic Resource
    Electronic Resource
    Voltage-dependent inhibition of the sodium pump by external sodium: Species differences and possible role of the N-terminus of the α-subunit (1993)
    Springer
    European biophysics journal 21 (1993), S. 433-443 
    Details
    ISSN: 1432-1017
    Keywords: Na-Pump current-voltage relationship ; Na dependence ; Access channel ; N-Terminus truncation ; (Xenopus oocyte)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Currents generated by the Na+/K+ ATPase were measured under voltage clamp in oocytes of Xenopus laevis. The dependence of pump current on external [Na+] was investigated for the endogenous Xenopus pump as well as for wild-type and mutated pumps of electroplax of Torpedo californica expressed in the oocytes. The mutants had α-subunits truncated before position Lys28 (αΔK28) or Thr29 (αΔT29) of the N-terminus. The currents generated by all variants of pump molecules in the presence of 5 mM K+ show voltage-dependent inhibition by external [Na+]. The apparent K1 values increase with membrane depolarisation, and the potential dependence can be described by the movement of effective charges in the electrical potential gradient across the membrane. Taking into account Na+-K+ competition for external binding to the E2P form, apparent K1 values and effective charges for the interaction of the Na+ ions with the E2P form can be estimated. For the Xenopus pump the effective charge amounts to 1.1 of an elementary charge and the K1 value at 0 mV to 44 mM. For the wild-type Torpedo pump, the analysis yields values of 0.73 of an elementary charge and 133 mM, respectively. Truncation at the N-terminus removing a lysinerich cluster of the a-subunit of the Torpedo pump leads to an increase of the effective charge and decrease of the K1 value. For αΔK28, values of 0.83 of an elementary charge and 117 mM are obtained, respectively. If LyS28 is included in the truncation (α·T29), the effective charge increases to 1.5 of an elementary charge and the apparent K1 value is reduced to 107 mM. The K, values for pump inhibition by external Na+, calculated by taking into account Na+-K+ competition, are smaller than the K/12 values determined in the presence of 5 mM [K+]. The difference is more pronounced for those pump variants that have higher Km, values. The variations of the parameters describing inhibition by external [Na+] are qualitatively similar to those described for the stimulation of the pumps by external [K+] in the absence of extracellular [Na+]. The observations may be explained by an acess channel within the membrane dielectric that has to be passed by the external Na+ and K+ ions to reach or leave their binding sites. The potential-dependent access and/or the interaction with the binding sites shows species differences and is affected by cytoplasmic lysine residues in the N-terminus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00185871
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  • 2
    Electronic Resource
    Electronic Resource
    Coordination Modes of 2,5-Di(tert-butyl)pyrrolide - Crystal Structures of HPyr*, Pyr*H·thf, (thf)2LiPyr*, and [(Me3Si)3C-Zn]2(μ-Cl)(μ-Pyr*) (Pyr* = 2,5-tBu2NC4H2) (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1175-1182 
    Details
    ISSN: 1434-1948
    Keywords: Hydrogen bonds ; Indium ; Lithium ; Nitrogen heterocycles ; Zinc ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The lithiation of 2,5-di(tert-butyl)pyrrole (1) yields bis(tetrahydrofuran)lithium 2,5-di(tert-butyl)pyrrolide (2), which is monomeric in solution as well as in the solid state. Due to the coordination number of three for the lithium atom, short Li-O and Li-N bond lengths of 193 pm are observed. The metathesis reaction of 2 with tris(trimethylsilyl)-methylzinc chloride (3) gives colorless bis[tris(trimethyl-silyl)methylzinc] chloride 2,5-di(tert-butyl)pyrrolide (4). The pyrrolide ligand and the chlorine atom bridge the zinc atoms. One of the zinc atoms is bonded to the nitrogen atom of the pyrrolide substituent, while the other bonds to the opposite C-C bond. At 215 pm, the Zn-N bond is very long compared to those in alkylzinc amides, whereas the Zn-C distances lie in the range of Zn-C bond lengths found between zinc and η5-bonded cyclopentadienide ligands. The molecular structures of 1 and of the low-melting THF adduct 1·thf show a similar 2,5-di(tert-butyl)pyrrole molecule, but in the latter case a weak N-H···O bond is observed (N-H 97 pm, O···H 199 pm).
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Amidinokomplexe von Molybdän(V) und Rhenium(V) Die Kristallstruktur von [Cl4Mo{i-Prop-NC(Cl) N-i-Prop}] (1985)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 522 (1985), S. 83-91 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Amidinocomplexes of Molybdenum (V) and Rhenium (V). Crystal Structure of [Cl4Mo{i-Prop-NC(Cl) N-i-Prop}]Molybdenum pentachloride and rhenium pentachloride, respectively, react with di-isopropylcarbodiimide in CCl4-suspensions forming the monomeric amidino complexes [Cl4M{i-prop-NC(Cl)N-i-prop}] (M = Mo, Re). According to the i.r. spectra the C—Cl-amidino ligand is bonded as a chelate. The molybdenum complex is characterized by an X-ray structure determination. It crystallizes in the tetragonalic space group I41/a with 8 formula units in the unit cell (1538 independent, observed reflexions, R = 0.051) with the lattice constants a = 1119 and b = 2332 pm.
    Notes: Molybdänpentachlorid bzw. Rheniumpentachlorid reagieren mit Di-isopropylcarbodiimid in CCl4-Suspensionen unter Bildung der monomeren Amidinokomplexe [Cl4M{i-Prop-NC(Cl)N-i-Prop}] (M = Mo, Re). nach den IR-Spektren ist der C-Chlor-amidinoligand als Chelat gebunden. Der Molybdänkomplex wurde durch eine röntgenorgraphische Strukturanalyse charakterisiert. Er kristallisiert in der tetragonalen Raumgruppe 141/a mit 8 Formeleinheiten pro Elementarzelle (1538 unabhängige, beobachtete Reflexe, R = 5,1%) mit den Gitterabmessungen a = 1119 und b = 2332 pm.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19855220310
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  • 4
    Electronic Resource
    Electronic Resource
    Die Kristallstruktur von [Cl4P{i-Prop-NC(Cl)N-i-Prop}] (1985)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 525 (1985), S. 143-149 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Crystal Structure of [Cl4P{i-Prop-NC(Cl)N-i-Prop}]The monomeric di-isopropylcarbodiimide complex [Cl4P{i-Prop-NC(Cl)N-i-Prop}] crystallizes in the monoclinic space group C2 with 4 formula units in the unit cell and with the lattice constants a = 1391.2(2), b = 708.6(1), c = 1463.5(2) pm and β = 95.76(1)°. The structure was refined to an R-value of 0.026 (2084 independent, observed reflexions). Main parts of the IR and Raman spectrum of the compound are discussed.
    Notes: Der monomere Di-isopropylcarbodiimidkomplex [Cl4P{i-Prop-NC(Cl)N-i-Prop}] kristallisiert in der monoklinen Raumgruppe C2 mit 4 Formeleinheiten pro Einheitszelle und den Gitterkonstanten a = 1391,2(2), b = 708,6(1), c = 1463,5(2) pm und β = 95,76(1)°. Die Struktur wurde bis zu einem R-Wert von 0,026 verfeinert (2 084 unabhängige, beobachtete Reflexe). Wichtige Abschnitte des IR- und Ramanspektrums der Verbindung werden diskutiert.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19855250616
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  • 5
    Electronic Resource
    Electronic Resource
    Massenspektroskopische Untersuchungen von 5-halogenierten PyrimidinglucuronidenHerrn Professor Dr. rer. nat. h. c. Dr. med. h. c. Manfred von Ardenne zum 75. Geburtstag gewidmet (1982)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 324 (1982), S. 177-186 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mass Spectroscopy of 5-Halogenated PyrimidinglucuronidesUsing the ion source according to von ARDENNE, useful spectra of negative and positive ions from sensitive glycosides were obtained either by electron attachment (EA-) or low voltage electron impact (EI-) mass spectroscopy.Spectra of glucuronides derived from 5-halogenated uracil, 2-thiouracil, 4-thiouracil and 6-mercaptopurin in their peracetylated, esterified and free acidic form are described. Most stable peracetylated 2- and 4-thiouracil glucuronides reveal intensive peaks of molecule ions.The halogen-carbon bonding strength, calculated from complementary aglycon peaks, demonstrates expected tendencies due to the halogen.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19823240202
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  • 6
    Electronic Resource
    Electronic Resource
    (RPNCH3)4, Cyclotetra(λ3-phosphazane) - Synthese und Kristallstrukturanalyse (1977)
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 89 (1977), S. 423-424 
    Details
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ange.19770890623
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  • 7
    Electronic Resource
    Electronic Resource
    Synthesis and Characterization of Substituted Benzyl Zinc Derivatives - Molecular Structures of (tmeda) Li-CH (GeMe3)Ph, (tmeda)Zn(CH2Ph)2, (tmeda)Zn[CH(SiMe3)Ph]2, and (tmeda)Zn[CH(SiMe3)Ph]N(H)Si(SiMe3)3Dedicated to Professor Manfred Weidenbruch on the occasion of his 60th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1499-1505 
    Details
    ISSN: 0009-2940
    Keywords: Lithium ; Zine ; Dibenzylzinc ; Tmeda complexes ; Heteroleptic alkylzinc amide ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of lithium phenyl(trimethylsilyl)methanide with phenyl(trimethylsilyl)methylzinc chloride-tmeda in the presence of tmeda yields the addition product, a bis(tmeda)-lithium dialkylchlorozincate. The elimination of lithium chloride leads to the formation of a tmeda adduct of bis[phenyl-(trimethylsilyl)methyl]zinc. The metathesis reaction of phenyl(trimethylsilyl)methylzinc chloride-tmeda with lithium tris(trimethylsilyl)silylamide allows the isolation of the corresponding heteroleptic tmeda complex of an alkylzinc amide. The metalation of phenyl(trimethylstannyl)methane with butyllithium yields the transmetalation product benzyllithium. From the metathesis reaction of this lithium base with anhydrous zinc(II) chloride in the presence of tmeda, the tmeda adduct of dibenzylzinc crystallizes. The molecular structures of (tmeda)Li—CH(GeMe3)Ph, (tmeda)Zn(CH2Ph)2, (tmeda)Zn[CH(SiMe3)Ph]2, and (tmeda)Zn[CH(SiMe3)-Ph[N(H)Si(SiMe3)3 are reported. Whereas lithium bonds in an η3-fashion, the zinc atom forms a σ(Zn—C) bond. The extremely wide Zn—N—Si angle in (tmeda)Zn[CH(SiMe3)-Ph[N(H)Si(SiMe3)3 of 157° is remarkable.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971301024
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  • 8
    Electronic Resource
    Electronic Resource
    Photoelektronenspektroskopische Untersuchungen an Divinylcyclobutanen (1981)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 994-1003 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Photoelectron Spectroscopic Investigations on DivinylcyclobutanesThe He(I) photoelectron (PE) spectra of cis/trans-1,3-divinylcyclobutane (1,2), cis/trans-1,2-divinylcyclobutanes (3,4), as well as the alkyl-substituted 1,2-divinylcyclobutanes 5-7 have been recorded. The interpretation is based on semiempirical calculations (MINDO/3, MNDO) and calculations using a ZDO-model. In case of 1-4 we determined the conformation of lowest energy by optimization of all geometrical parameters. The orbital energies calculated for this conformation agree very well with the measured vertical ionization potentials.
    Notes: Die He(I)-Photoelektronen (PE)-Spektren von cis/trans-1,3-Divinylcyclobutan (1,2), cis/trans-1,2-Divinylcyclobutan (3,4) sowie der alkylsubstituierten 1,2-Divinylcyclobutane 5-7 werden mit Hilfe semiempirischer Rechnungen (MINDO/3, MNDO) und eines ZDO-Modells interpretiert. Bei 1-4 wurde durch Geometrieoptimierung die anti-bisektierte Konformation in jedem Falle als die mit niedrigster Energie bestimmt. Die Orbitalenergien, die für diese Konformation berechnet werden, ergeben eine gute Übereinstimmung mit den gemessenen vertikalen Ionisationspotentialen.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19811140318
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  • 9
    Electronic Resource
    Electronic Resource
    Über die Synthese von 1,1′-Bicyclobutyl- und 1,1′-Bicyclohexyl-Derivaten (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 2554-2563 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of 1,1′-Bicyclobutyl and 1,1′-Bicyclohexyl DerivativesDimeric glycols (2, 3 and 20, 24) are prepared from ethyl 3-oxocyclobutanecarboxylate (1) and 4-substituted cyclohexanone derivatives 9, 10, 23 by low valent titanium reagents. Dimeric olefins (17, 18) were obtained from the cyclohexanones by Barton's thiadiazoline method. Some experiences with cis-protecting groups for the 1,1′-dihydroxy dimers are presented.
    Notes: Aus dem 3-Oxocyclobutancarbonsäure-ethylester (1) und 4-substituierten Cyclohexanonen 9, 10, 23 werden mit niederwertigem Titan die dimeren Glycole 2, 3 bzw. 20, 24 hergestellt, aus den Cyclonexanonen mit Bartons Thiadiazolin-Methode auch die dimeren Olefine 17, 18. Einige Erfahrungen mit den Schutzgruppen zur cis-Fixierung der 1,1′-Dihydroxy-Dimeren werden mitgeteilt.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831160714
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  • 10
    Electronic Resource
    Electronic Resource
    Synthesis and Dynamic Behavior of the Dimeric, Monocyclic Barium Bis[bis(isopropyldimethylsilyl)phosphanide] - Molecular Structures of P(SiMe2Ph)3, of Monomeric (thf)4Ba[P(SiMe2iPr)2]2 and of the Dimer {(thf)2Ba[P(SiMe2iPr]2]2}2 (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 1035-1040 
    Details
    ISSN: 0009-2940
    Keywords: Phosphanes ; Bis(silyl)phosphanes ; Tris(silyl)phosphanes ; Phosphanides ; Barium bis(phosphanide) ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Barium bis[bis(trimethylsily)amide] metalates bis(isopropyldimethylsilyl)phosphane (1) to yield nearly quantitatively the corresponding barium bis[bis(isopropyldimethylsilyl)phosphanide] (3). This compound shows a temperature-dependent monomer-dimer equilibrium in toluene solution. Both the isomers were characterized by X-ray crystal structure analyses. The monomeric derivatives precipitate as a tetrakis(tetrahydrofuran) complex with a P-Ba-P bond angle of 139.9°. The barium atoms of the monocyclic, centrosymmetric dimer are pentacoordinated by two tetrahydrofuran molecules, one terminal and two bridging phosphanide ligands. The endo- and exocyclic Ba-P distances with values of 332 and 316 pm, respectively, lie within the characteristic range.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19961290910
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