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  • 1
    Electronic Resource
    Electronic Resource
    The calmodulin fraction responsible for contraction in an intestinal smooth muscle
    Amsterdam : Elsevier
    FEBS Letters 170 (1984), S. 383-386 
    Details
    ISSN: 0014-5793
    Keywords: Calmodulin ; Contraction control ; Myosin light chain kinase ; Smooth muscle ; Taenia coli
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0014-5793(84)81349-6
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  • 2
    Electronic Resource
    Electronic Resource
    Identification of the residues on cyclic GMP-dependent protein kinase that are autophosphorylated in the presence of cyclic AMP and cyclic GMP
    Amsterdam : Elsevier
    Biochimica et Biophysica Acta (BBA)/Protein Structure and Molecular 790 (1984), S. 219-225 
    Details
    ISSN: 0167-4838
    Keywords: Autophosphorylation ; Phosphoamino acid ; Protein kinase ; cyclic AMP ; cyclic GMP
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0167-4838(84)90025-6
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  • 3
    Electronic Resource
    Electronic Resource
    Structure and physiological role of cGMP-dependent protein kinase
    Amsterdam : Elsevier
    Biochimica et Biophysica Acta (BBA)/Molecular Cell Research 1135 (1992), S. 51-60 
    Details
    ISSN: 0167-4889
    Keywords: Enzyme regulation ; Enzyme structure ; Protein kinase ; Substrate phosphorylation ; cyclic GMP
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Medicine , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0167-4889(92)90165-8
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  • 4
    Electronic Resource
    Electronic Resource
    Relaxation of skinned coronary arteries depends on the relative concentrations of Ca2+, calmodulin and active cAMP-dependent protein kinase (1985)
    Springer
    Pflügers Archiv 405 (1985), S. 70-76 
    Details
    ISSN: 1432-2013
    Keywords: Skinned coronary arteries ; Smooth muscle ; Regulation of contractile tone ; cAMP-dependent protein kinase ; cAMP-dependent modulation of contractile tone ; Calmodulin ; Calcium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Maximally contracted detergent skinned coronary smooth muscle fibres are relaxed by lowering the concentration of free Ca2+. The extent and rate of relaxation depends on the concentration of free Ca2+ and calmodulin (CaM) suggesting that it is the Ca2+. CaM complex which is responsible for maintaining tension. At a fixed concentration of Ca2+ and CaM further relaxation can be achieved by addition of the catalytic subunit of the cAMP-dependent protein kinase (cAMP-kinase). The extent as well as the relaxation rate depend on the concentration of cAMP-kinase (0.01–0.5 μM) and both are antagonized by high concentrations of Ca2+ and CaM. The Ca2+-requirement for obtaining half maximal concentration is shifted from 1.1 μM to 6.3 μM Ca2+ in the presence of 0.5 μM cAMP-kinase. These data indicate that the response of the contractile apparatus to a change in the free [Ca2+] can be modulated by cAMP-kinase at the level of the contractile proteins. It is further suggested that the tone of coronary smooth muscle is determined by the relative and not by the absolute concentrations of Ca2+, CaM and cAMP-kinase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00591100
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  • 5
    Electronic Resource
    Electronic Resource
    Hydroxidgruppen an Zeolithen. II. Zahl und Eigenschaften von Hydroxidgruppen an CeNaY- und HNaY-Zeolithen unterschiedlichen Austauschgrades (1974)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 404 (1974), S. 142-160 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Hydroxide Groups on Zeolites. II. Number and Properties of Hydroxide Groups on CeNaY and HNaY Zeolites of Different Exchange DegreeThe number of hydroxide groups on CeNaY and HNaY zeolites was examined by D2 exchange, and their properties in dependence of the cation exchange degrees were studied by IR spectroscopy. On CeNaY zeolites there exist six kinds and on HNaY zeolites at least seven kinds of hydroxide groups.On the CeNaY zeolites, the hydroxide groups are produced by dissociative chemisorption of water on Ce3+ ions. Their total number increases continuously with increasing exchange degree. Some of the hydroxide groups are acid BRÖNSTED centers whose number increases with increasing exchange degree and decreases with the temperature of preheating increasing to about 600°C.On the HNaY zeolites, the hydroxide groups are produced by thermal decomposition of the NH+4 ions, by dealumination and interaction of the Al3+ ions produced in this way in the place of cations with water. Above the threshold value of 35% the total number of the hydroxide groups increases very rapidly with increasing exchange degree. One part of the hydroxide groups decreasing with increasing exchange degree acts as acid BRÖNSTED centers. The number of these centers does not decrease until at preheating temperatures above 450°C.
    Notes: An CeNaY- und HNaY-Zeolithen wurden durch D2-Austausch die Zahl und infrarotspektroskopisch die Eigenschaften der Hydroxidgruppen in Abhängigkeit vom Kationenaustauschgrad untersucht. Es existieren an CeNaY-sechs Arten und an HNaY-Zeolithen mindestens sieben Arten von Hydroxidgruppen.An den CeNaY-Zeolithen entstehen die Hydroxidgruppen durch dissoziative Chemisorption von Wasser an Ce3+-Ionen. Ihre Gesamtzahl wächst kontinuierlich mit steigendem Austauschgrad. Einige der Hydroxidgruppen sind saure BRÖNSTED-Zentren, deren Zahl mit steigendem Austauschgrad wächst und mit steigender Vorerhitzungstemperatur bis etwa 600°C sinkt.An den HNaY-Zeolithen entstehen die Hydroxidgruppen durch thermische Zersetzung der eingetauschten NH+4-Ionen und mit wachsendem Austauschgrad zunehmend durch das Herauslösen von Gitteraluminium und Wechselwirkung der so entstehenden Al3+-Ionen auf Kationenplätzen mit Wasser. Die Gesamtzahl der Hydroxidgruppen wächst oberhalb des Schwellenwertes von 35% sehr stark mit steigendem Austauschgrad an. Ein mit steigendem Austauschgrad abnehmender Anteil der Hydroxidgruppen wirkt als saure BRÖNSTED-Zentren, deren Zahl erst bei Vorerhitzungstemperaturen oberhalb von 450°C abnimmt.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19744040206
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  • 6
    Electronic Resource
    Electronic Resource
    Untersuchungen an oxidischen Katalysatoren. XXIX. Spektroskopische und katalytische Untersuchungen an Ni2+-, Co2+-, Cr3+- und Cu2+-ausgetauschten MordenitenProfessor Günther Rienäcker gewidmet (1979)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 452 (1979), S. 6-16 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Studies on Oxide Catalysts. XXIX. Spectroscopic and Catalytic Investigations on Ni2+-, Co2+-, Cr3+-, and Cu2+-exchanged MordenitesNiNaM, CoNaM, CrNaM und CuNaM (M = Mordenite) have been characterized by UV-VIS, EPR and i.r. spectroscopy and the results were compared with the catalytic activity and the activity-time-dependence in the cracking of n-octane and with the shape selectivity in the cracking of a n-octane and isooctane mixture. Water molecules acting as ligands of the exchanged cations are able to dissociate yielding Brönsted acidity. Brönsted sites may be regarded as catalytic active centers in the cracking reaction. Unreduced transition metal cations facilitate the “coking” of the mordenite.The unreduced chromium and cobalt cations for which a position within the main channel is expected, affect the diffusion of the branched paraffin molecule thus increasing shape selectivity.
    Notes: NiNaM, CoNaM, CrNaM und CuNaM (M = Mordenit) wurden durch UV-VIS-Spektroskopie, EPR- und IR-Untersuchungen charakterisiert und die erhaltenen Ergebnisse mit der katalytischen Aktivität und dem Aktivitäts-Zeit-Verhalten dieser Proben bei der Spaltung von n-Octan und der Formselektivität in der Spaltung eines Gemisches von n/iso-Octan verglichen. Wassermolekeln als Liganden der eingetauschten Kationen können dissoziieren und so einen Beitrag zur Brönsted-Acidität liefern. Die Brönsted-Zentren können als katalytisch aktive Zentren in der Spaltreaktion angesehen werden. Nichtreduzierte Übergangsmetallkationen vergrößern die Neigung des Mordenits zum „Verkoken“ wesentlich. Die nichtreduzierten Co2+- und Cr3+-Kationen, für die eine Position im Hauptkanal angenommen werden kann, wirken als zusätzliche Diffusionsbremse auf die verzweigte Paraffinmolekel und erhöhen die Formselektivität des Mordenits.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19794520103
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  • 7
    Electronic Resource
    Electronic Resource
    Untersuchungen an oxidischen Katalysatoren. XLII. Redoxverhalten des Nickels in NiNa—Y-Zeolithen 4. Einfluß der Zusammensetzung auf die Reduzierbarkeit von Nickel in NiNa—Y-Zeolithen (1985)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 521 (1985), S. 145-152 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Studies on Oxide Catalysts. XLii. Redox Behaviour of Nickel in Zeolites NiNa—Y. 4. Influence of Composition on the Reducibility of Nickel in Zeolites NiNa—YBy chemical analysis (reaction with K2Cr2O7) and ESCA investigations we determined the degree of reduction in reduced samples NiNa-Y as function of the mole ratio SiO2/Al2O3 (module), of the Ni2+ degree of exchange and the kind of the second cations. (NH4+, Ca2+, Co2+, and Nd3+) in the temperature region of 620-770 K. The degree of nickel reduction increases with increasing module, decreasing degree of exchange and decreasing number of Brönsted acidic centres. This behaviour is caused by the influence of the interaction between cations Ni2+ and zeolite lattice on the reduction equilibrium.
    Notes: Durch chemische Analyse (Reaktion mit K2Cr2O7) un ESCA-Untersuchungen wird in reduzierten NiNa—Y-Proben der Nickel-Reduktionsgrad als Funktion des SiO2/al2O3-Verhältnisses (Modul), des Nickelaustauschgrades und der Art eines Zweitkations (NH4+ +, Ca2+, Co2+, Nd3+) im Temperaturbereich von 620 - 770 K bestimmt. Der Nickel-Reduktionsgrad steigt mit wachsendem Modul, sinkendem Austauschgrad und sinkender Zahl Brönsted-acider Zentren. Die Ursache dafür wird in dem Einfluß der Ni2+-Zeolithgitter-Wechselwirkung auf das Reduktionsgleichgewicht gesehen.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19855210217
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  • 8
    Electronic Resource
    Electronic Resource
    Hydroxidgruppen an Zeolithen. III. Eigenschaften von Hydroxidgruppen an ZnNaY-, CuNaY-, NiNaY- und CrNaY-Zeolithen (1974)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 407 (1974), S. 162-172 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Hydroxide Groups on Zeolites. III. Properties of Hydroxide Groups on ZnNaY, CuNaY, NiNaY, and CrNaY ZeolitesThe properties of hydroxide groups in dependence on the degree of exchange were studied by IR spectroscopy of ZnNaY, CuNaY, NiNaY, and CrNaY zeolites. Five kinds of hydroxide groups occur on these zeolites: Hydroxid groups limiting the lattice, 3 kinds of structural hydroxide groups, and MeOH+ groups. These are the same kinds of hydroxide groups as exist on alkaline earths-Y-zeolites. Some of the OH groups act as acid Brönsted centers. The number of acid Brönsted centers reaches maximum values at degrees of exchange of 40-50% after a pretreatment at 300-400°C. The zeolitic structure is partially destroyed in ZnNaY, CuNaY, and especially CrNaY, at high degree of exchange.
    Notes: An ZnNaY-, CuNaY-, NiNaY- und CrNaY-Zeolithen wurden die Eigenschaften der Hydroxidgruppen in Abhängigkeit vom Austauschgrad infrarotspektroskopisch untersucht. An diesen Zeolithen treten fünf Arten von Hydroxidgruppen auf, nämlich gitterbegrenzende Hydroxidgruppen, drei Arten von strukturellen Hydroxidgruppen und MeOH+-Gruppen. Dabei handelt es sich um die gleichen Arten von Hydroxidgruppen wie an Erdalkali-Y-Zeolithen. Einige der OH-Gruppen wirken als saure Brönsted-Zentren. Die Zahl der sauren Brönsted-Zentren erreicht Maximalwerte bei Austauschgraden von 40-50% nach einer Vorbehandlung bei 300-400°C. Bei ZuNaY-, CuNaY- und besonders stark bei CrNaY-Zeolithen wird bei hohen Austauschgraden die Zeolithstruktur teilweise zerstört.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19744070207
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  • 9
    Electronic Resource
    Electronic Resource
    Hydroxidgruppen an Zeolithen. I. Zahl und Eigenschaften von Hydroxidgruppen an CaNaY- und MgNaY-Zeolithen unterschiedlichen Austauschgrades (1974)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 404 (1974), S. 129-141 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Hydroxide Groups on Zeolites. I. Number and Properties of Hydroxide Groups on CaNaY and MgNaY Zeolites of Different Degree of Ion ExchangeThe number of hydroxide groups was studied on CaNaY and MgNaY zeolites by D2 exchange in dependence on the degree of exchange, and their properties were examined by infrared spectroscopy. At these zeolites there exist five types of hydroxide groups which differ by their concentration, their acidic strength, and their thermal stability. The OH-groups are produced mainly by dissociative chemisorption of water at the bivalent cations. The concentration of OH groups shows a characteristic dependence on the degree of ion exchange. There are OH groups which are strongly acid BRÖNSTED centers, capable of protonisation of pyridine, and others which are only capable of weak interactions with pyridine. The number of the acid BRÖNSTED centers increases with the degree of ion exchange analogous to the total number of the hydroxide groups and is highly dependent on the species of the cations exchanged and on the preheating temperature. Compared with CaNaY zeolites, MgNaY zeolites posess a greater number of hydroxide groups which are thermally more stable.
    Notes: An CaNaY- und MgNaY-Zeolithen wurden in Abhängigkeit vom Austauschgrad durch D2-Austausch die Zahl und infrarotspektroskopisch die Eigenschaften der Hydroxidgruppen untersucht. Es existieren an diesen Zeolithen fünf Arten von Hydroxidgruppen, die sich in ihrer Konzentration, ihrer Säurestärke und ihrer thermischen Stabilität unterscheiden. Die OH-Gruppen entstehen vorwiegend durch dissoziative Chemisorption von Wasser an den zweiwertigen Kationen. Die Konzentration der OH-Gruppen hängt charakteristisch vom Austauschgrad ab. Es gibt OH-Gruppen, die stark saure BRÖNSTED-Zentren sind und Pyridin protoisieren können, und solche, die nur schwache Wechselwirkung mit Pyridin eingehen können. Die Zahl der sauren BRÖNSTED-Zentren steigt analog der Gesamtzahl der Hydroxidgruppen mit dem Austauschgrad an, sie hängt von der Art der eingetauschten Kationen und der Vorerhitzungstemperatur stark ab. MgNaY-Zeolithe besitzen mehr und thermisch stabilere Hydroxidgruppen als CaNaY-Zeolithe.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19744040205
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  • 10
    Electronic Resource
    Electronic Resource
    Untersuchungen zur Acidität und katalytischen Spaltaktivität dekationisierter NaY-Zeolithe (1981)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 481 (1981), S. 168-174 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Investigation on Acidity and Catalytic Activity of Deep-Bed Calcinated Zeolites NH4 NaYNMR and infrared techniques are applied to decationated zeolites NaY to study Brönsted acidity. The results are compared with measurements of catalytic activity and crystallinity of this zeolites.The number of OH groups which are able to form a pyridinium ion (PyH+) increases with increasing exchange degree and with increasing temperature of the sample. The rate of pyridinium ion formation as an equivalent of Brönsted acidity and the catalytic activity increase similarly with increasing exchange degree up to such values where a loss of crystallinity occurs.
    Notes: Methoden der NMR- und der IR-Spektroskopie werden zur Charakterisierung der Brönsted-Acidität unterschiedlich dekationisierter NaY-Zeolithe eingesetzt. Die erhaltenen Ergebnisse werden im Zusammenhang mit den Ergebnissen katalytischer Messungen und Kristallinitätsuntersuchungen interpretiert.Es zeigt sich, daß die Zahl der an der Bildung von Pyridiniumkationen (PyH+) beteiligten OH-Gruppen sowohl mit wachsendem NH4+-Austauschgrad als auch bei Erhöhung der Meßtemperatur zunimmt. Die Geschwindigkeit der Bildung von Pyridiniumkationen als relatives Maß für die Brönsted-Acidität und die katalytische Spaltaktivität verändern sich in der gleichen Weise mit dem Austauschgrad. In Proben mit höheren Austauschgraden werden Acidität und Aktivität von Kristallinitätsverlusten beeinflußt.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19814811018
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