Kinetics and mechanism of the hydrolysis of sodium carboxymethylcellulose (Na-CMC) by a cellulase complex

TheSomogyi-Nelson colorimetric method is applied in a new manner more suitable for evaluating the kinetics of the enzyme hydrolysis of sodium carboxymethylcellulose (Na-CMC) catalyzed by the cellulase complex. By means of selective inhibition of a chosen enzyme from the cellulase complex it became possible to trace the effect of the other enzymes included in its composition.

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Kinetik und Mechanismus der Hydrolyse von Natriumcarboxymethylcellulose (Na-CMC) durch einen Cellulase-Komplex

Zusammenfassung Die kolorimetrische Methode nachSomogyi undNelson wird nach einem neuen Verfahren zur Verfolgung der Kinetik der hydrolytischen Spaltung von Natriumcarboxymethylcellulose (Na-CMC), katalysiert durch den Cellulase-Komplex, angewandt. Durch selektive Inhibierung eines bestimmten Enzyms des Cellulase-Komplexes kann man die Wirkung der anderen zu seiner gesamten Zusammensetzung gehörenden Enzyme verfolgen.

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Symbols Used E enzyme (E—cellulase;E—exo-cellobiohydrolase;E—-glucosidase) - [E] _w weight concentration of enzymeE - S substrate (Na-CMC—sodium carboxymethylcellulose) - [S]₀ weight concentration of substrateS - I inhibitor (I—lactose;I—calcium chloride;I—condurrite-B-epoxide) - P product (P—oligosaccharides;P—cellobiose;P—D-glucose) - P end product (K , K , K ) - DP degree of polymerization - DS degree of substitution - ES enzyme-substrate complex (E S, E S, E S) - EP enzyme-product complex (E P, E P) - EI enzyme-inhibitor complex (E I, E I, E I) - M _s molecular mass of substrateS - K _s substrate constant (K _s , K _s , K _s ) - K _I inhibitor constant (K _I , K _I , K _I ) - K _m Michaelis-Menten constant - k ₊₁,k ₊₂ (k ₊₂ ,k ₊₂ ,k ₊₂ ) forward rate constants - k _–1 reverse rate constant - ₀ initial rate of reaction - V maximal reaction rate - A change in absorbance - molar absorption coefficient - wavelength Herrn Prof. Dr.Hans Tuppy zum 60. Geburtstag herzlichst gewidmet.     

Ruthenium(ii) complexes with tetra-15-crown-5-phthalocyanine: synthesis and spectroscopic investigation

The ruthenium complexes with tetra-15-crown-5-phthalocyanine and various axial ligands were synthesized and characterized by spectroscopy. A method for the synthesis of bisaxially coordinated ruthenium(ii) tetra-15-crown-5-phthalocyaninates with the N-donor ligands (R₄Pc)Ru(L₂) (R₄Pc^2– = [4,5,4",5",4,5,4,5-tetrakis(1,4,7,10,13-pentaoxotridecamethylene)phthalocyaninate-ion], L is trimethylamine (Me₃N), pyridine (py), isoquinoline (iqnl), triethylamine (Et₃N), pyrazine (pyz)) was developed. The preparation technique involves selective decarbonylation of (R₄Pc)Ru(CO)(MeOH) on treatment with Me₃NO in excess N-donor solvent.     

Role of acid centers of Sn/Mo oxide catalyst in propylene conversion to acetone

Infrared spectroscopic studies of the nature of catalyst centers indicate the presence of Brönsted and Lewis acid centers on the surface. Propylene conversion to acetone proceeds via proton transfer from the surface to propylene with the formation of a (CH₃)₂–C(H)–O–Me type compound, and its subsequent dehydration.

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- , . (CH₃)₂–C(H)–OMe .

     

Ethane hydrogenolysis on silica-supported tantalum hydride. Quantum-chemical study

The structures of the (H₄Si₂O₅)O₂Ta(R, RR"R, RR) clusters (R, R", R = H, Me, Et, Pr; R = CH₂), which model the basic structural units of the catalytic cycle of ethane hydrogenolysis on silica-supported tantalum hydride, were studied by the density functional theory (B3LYP) and the perturbation theory (MP2). The possible structure of active sites was proposed based on comparison of experimental results with calculated data. Ethane hydrogenolysis and metathesis proceed by a mechanism involving the formation of ethylene -complexes and carbenium derivatives of tantalum as intermediates.     

Mechanism of formation of applicable linear boron-nitrogen polymers

This paper contains a literature review on the mechanism of formation of applicable linear boron-nitrogen polymers.

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Zusammenfassung Dieser Artikel enthält eine Literaturübersicht über den Bildungsmechanimus anwendbarer Bor-Stickstoffpolymerer.

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Résumé Cet article contient une revue des publications sur le mécanisme de formation des polymères de bore-azote.

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1H-NMR-spektroskopische Analyse von 2-Chlor-1.3.2-dioxarsolan

The¹H-NMR-spectral data of 2-chloro-1.3.2-dioxarsolane are presented and discussed. The protons of the methylene groups form in concentrated solutions by rapide chlorine exchange anAAAA spin system. In dilute solutions the protons form anAABB spin system, which is changed to anAAAA system by addition of chlorine ions.The vicinal H–C–C–H-coupling constants indicate a twist-envelope conformation.

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Mit 1 Abbildung     

Self-oscillations in the cool-flame combustion of a model n-heptane-isooctane mixture

Self-oscillation found experimentally in the cool-flame combustion of a model n-heptane-i-octane mixture has been studied in dependence on the composition of the reaction mixture. Calculations based on the CSTR model are in qualitative agreement with experimental data.

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Catalytic properties of Ti?Mo oxide catalysts in propylene oxidation

Catalytic properties of Ti–Mo oxide catalysts are shown to be determined to a great extent by the Ti–Mo heteropoly acid anchored to the TiO₂ surface which is formed during the catalyst preparation.

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Adsorption characteristics of a Hungarian natural mordenite and its acid treated derivatives

A mordenite-containing rock from the Tokaj-mountains was investigated. The effect of the treatment with hydrochloric acid solutions of various molarity was established. From gas adsorption measurements, scanning electron microscopic investigations and measurements with a mercury porosimeter conclusions were drawn on the changes caused by acid treatment. Slight changes in the texture were found, but no damage in the crystal structure could be observed.

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Zur Frage des Einsatzes ionenspezifischer Elektroden in der Automation

Zusammenfassung Es wurden Untersuchungen mit anionenspezifischen Membranelektroden nach Pungor durchgeführt. Dazu werden Reproduzierbarkeit, Eichfunktion, Einstellzeiten bei auf- und absteigender Konzentration und Querempfindlichkeit im Hinblick auf den Einsatz in automatischen Systemen behandelt. Es wird vorgeschlagen, für die Angabe der Selektivität einen p-Sel analog zum pH zu verwenden, die Behandlung eines Analysensensorsystems wird vorgenommen.

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On the use of ion-specific electrodes in automation

Investigations on anion-specific membrane electrodes are described. Problems of reproducibility, calibration, time-response in respect of in- and decreasing concentrations and sensitivity to interfering ions are demonstrated and discussed with regard to automation. It is proposed to define a p-sel for the selectivity constant analogue to pH and a calculation method for an Analysis-Sensor-System is shown.

     

Kinetic analysis of the liquid-phase depolymerization of trioxane from programmed-temperature data

An experimental method for the determination of kinetic data for liquid-phase reactions under linear rise of temperature is explained for the depolymerization of trioxane. Integral kinetic analysis of the data is performed in order to determine the kinetic model and the kinetic parameters. Experiments have been carried out at different heating rates between 0.5 and 2 deg/min, leading to similar kinetic parameters. The obtained results are in agreement with the kinetic model and parameters obtained from isothermal kinetic analysis. The programmedtemperature method seems to be a useful tool for a quick determination of kinetic models, avoiding experimental work.

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Zusammenfassung Eine experimentelle Methode zur Bestimmung der kinetischen Daten von Reaktionen in flüssiger Phase bei linearer Temperaturerhöhung wird am Beispiel der Depolymerisation von Trioxan erklärt. Eine integrale kinetische Analyse der Daten wird ausgeführt, um das kinetische Modell und die kinetischen Parameter zu ermitteln. Bei unterschiedlicher Aufheizgeschwindigkeit zwischen 0,5 und 2 K/min ausgeführte Experimente ergaben ähnliche kinetische Parameter. Die erhaltenen Ergebnisse stimmen mit dem kinetischen Modell und den kinetischen Parametern, die durch isotherme kinetische Analyse erhalten wurden, überein. Die Temperaturprogrammierung scheint eine brauchbare, experimentelle Arbeit einsparende Methode zur schnellen Bestimmung des kinetischen Modells zu sein.

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. . , (0,5–2° .), . , . , .

     

Structure of psolusoside B — A nonholostane triterpene glycoside of the holothurian genus Psolus

The structure of psolusoside B — a minor triterpene oligoglycoside from the holothurianPsolus fabricii and the main glycoside fromPsolus sp. has been determined by the methods of partial acid hydrolysis, methylation,¹³C NMR, and FAB mass spectrometry as 20S-acetoxy-3-{2-O-[O--D-glucopyranosyl-(1 4)-O--D-glucopyranosyl]-4-O-(6-O-sulfato--D-glucopyranosyl)--D-xylo-pyranosyloxy}holosta-7,25-diene-18,16-carbolactone. 3-[O-(3-O-Methyl-6-O-sulfato--D-glucopyranosyl)-(1 3)-O-(6-O-sulfato--D-glucopyranosyl)-(1 4)-O--D-quinovopyranosyl-(12)--D-xylopyranosyloxy]holosta-9(11),25-dien-16-one (psolusoside A), known previously forPsolus fabricii, has been identified in a holothurian —Psolus sp. — from Kraternaya Bay (island of Ushishir).Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Branch, Academy of Sciences of the USSR, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 361–368, May–June, 1989.     

Structure of some components of the roots of Prangos ferulacea

Summary From a methanolic extract of the roots ofPrangos ferulacea (L) Lindl., growing in the Nakhichevan ASSR, in addition to the compounds found previously, another six substances (I–VI) have been isolated, of which (I) and (VI) have been identified as, respectively, meransin hydrate monoacetate, found for the first time in nature, and umbelliferone: and in the study of a crystalline mixture obtained from the resin of the roots of the plant under investigation collected in Armenia, two coumarins — (VII) and (VIII) — have been isolated.On the basis of a study of IR, NMR, and mass spectra and chemical properties, the structures of the six new cumarin derivatives (II–V, VII, and VIII) have been established. Compound (II) has the structure of 8-(3-methylbutenyloxy)furo-2,3:7,6-coumarin and has been called feruliden; (III) is 7-hydroxy-8-(3-hydroxy-2-senecioyloxyisopentyl) coumarin and has been called ferudiol; (IV) is 7-hydroxy-8-(3-methoxy-2-senecioyloxyisopentyl) coumarin; (V) is 5-[1-(2,3-dihydroxy-3-methylbutyroyloxy)-1-methylethyl]-4,5-dihydrofuro-2,3:7,6-coumarin and has been called lindiol; (VII) is 8-(2-hydroxy-3-methylbut-3-enyloxy)-7-methoxycoumarin and has been called ferudenol; (VIII) is 7-methoxy-8-(3-methyl-2-oxobut-3-enyl)coumarin and has been called prangone.Leningrad Sanitary-Hygenic Medical Institute. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 568–574, September–October, 1974.     

Synthetic investigations in the field of the curare alkaloids

It has been shown that the compounds obtained previously corresponding in comparison to the -[4-(5-carboxymethyl-2-hydroxyphenoxy)3-methoxyphenyl]ethylamide of 4-benzyloxyphenylacetic acid have practically the same spectra and on further condensation with 3-bromo-4-hydroxy-5-methoxyphenylethylamine give an equilibrium mixture of diamide compounds. The difference in the physicochemical properties of the diphenyl esters and the diamides can be explained by steric differences. On cyclization, the diamides are converted into bis-dihydroisoquinoline compounds of the same elementary composition. The hydrochloride of 7-[2-acetoxy-5-(7-acetoxy-8-bromo-6methoxy-3, 4dihydroisoquinol-1-ylmethyl)phenoxyl)-1-(4-benzyloxybenzyl)-6-methoxy-3,4-dihydroisoquinoline, with mp 180–181° C, after saponification, intramolecular Ullman condensation, reduction, and stepwise methylation, was converted into isomeric tubocurarin iodides with mp 189–190.5° C, 164–166.5° C, 257–260.5° C, and 210–212° C, which were separated on the basis of their different solubilities in organic solvents and water.For part XII, see [1].     

Formulas for \bar \beta parameters and their limitations

The operator relationship p=[r, h] between linear momentum, position vector and Hamiltonian is the basis for an investigation of formulas for ¦ atomic orbitals is discussed. Formulas for parameters useful in extended Hückel methods are presented.

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Zusammenfassung Die Operatorengleichung p=[r, h] zwischen Impuls, Ortsvektor und Hamiltonoperator ist die Grundlage für eine Untersuchung von Formeln für -Parameter in der erweiterten Hückel[1]- und CNDO [2]-Methode. Das Eichproblem dieser Gleichung in Verbindung mit abgebrochenen Entwicklungen für Matrixelemente ¦P¦ über Atomfunktionen wird diskutiert. Nützliche Formeln für die erweiterte Hückel-Methode werden abgeleitet.

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Résumé La relation entre opérateurs moment linéaire, position et hamiltonien: p=[r, h] sert de base à une étude de formules pour les paramètres dans les méthodes de type Hückel étendu [1] et CNDO [2]. Le problème de jauge de cette équation est discuté par rapport au développement limité des éléments de matrice ¦P¦ dans une base d'orbitales atomiques. Présentation de formules pour les paramètres utiles dans les méthodes Hückel étendu.

     

Crystal and Molecular Structure of (BzlMe3N) 2 + [Fe2OCl6]2-

The crystal and molecular structure of (BzlMe₃N) ₂ ⁺ [Fe₂OCl₆]^2- has been determined. The asymmetric unit contains two benzyltrimethylammonium cations and two half -oxo-bis(trichloro-iron(III)) anions. The bridging -oxygen atoms of these anions are located over crystallographic symmetry elements. Therefore, the two anions resulting from the symmetry operations correspond to two different conformers presenting angular and linear dispositions of the Fe-O-Fe bond angle. Mössbauer spectrum consists of two asymmetric lines that are adequately simulated by two equally populated quadrupole doublets associated with the two iron sites.     

Formation and stability of superoxide ions in Rh-zeolite catalysts

Adsorption of O₂ at 25°C on Rh-zeolites previously activated under O₂ at >200°C, then under vacuum at >400°C generates several paramagnetic species. Possible assignments and support effects are discussed.

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25°C Rh-, >200°C, >400°C, . , .

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NRCC contribution No.     

A Note on Distance Matrices Yielding Elementary Landscapes for the TSP

Symmetric and antisymmetric distance matrices in the single agent traveling salesman problem (TSP) are not the only distance matrices to generate elementary landscapes for swap and 2-opt neighborhoods.     

Possibilities of applying the piloyan method of determination of decomposition activation energies in the differential thermal analysis of polynitroaromatic compounds and their derivatives

Piloyan activation energiesE as well as initals of exothermT _D of sevenN-monoalkyl and fiveN,N-dialkyl-2,4-dinitroanilines were determined. Relationships were found between the T_D values and R_f factors as well asE values and those R_M functions and also theET _D ^–1 term and R_M functions.

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Zusammenfassung Die AktivierungsenergienE nach Piloyan sowie die Anfangswerte der ExothermenT _D wurden für siebenN-Monoalkyl- und fünfN,N-Dialkyl-2,4-dinitroaniline bestimmt. Die Zusammenhänge zwischen denT _D-Werten und den papierchromatographischenR _f-Faktoren der gemessenen Dinitroaniline wurden abgeleitet und erörtert. Desgleichen wurden auch die Zusammenhänge zwischen denE-Werten und denR _M-Funktionen der Papierchromatographie abgeleitet und erörtert. Auch zwischen dem AusdruckE ·T _D ^–1 und denR _M-Funktionen wurde ein Zusammenhang gefunden.

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Résumé On a déterminé les températures initialesT _D de l'effet exothermique ainsi que les énergies d'activationE d'après la méthode de Piloyan, de sept N-mono alcoyl et cinqN,N-dialcoyl-2, 4-dinitroanilines. Une corrélation entre les valeursT _D et les facteursR _f de la Chromatographie sur papier des dinitroanilines étudiées a été trouvée et discutée, ainsi qu'entre les valeursE et les fonctionsR _M de la Chromatographie sur papier. Une relation entre le termeE ·T _D ^–1 et les fonctionsR _M a également été trouvée.

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E T _D N- N,N- -2,4- . _D R _f , E R _M. E. _D ^–1 R _M.

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The authors would like to thank Mrs. Anna Collàkovà for careful DTA measurements, and Dr. Ladislav Smolka for help in treatment of the measured results with the Wang 600 computer.     

Thermal investigation of the phase composition of poly(ethylene terephthalate). Analysis of different methods of determination of the degree of crystallinity of partially crystalline substances

The literature data on the degree of crystallinity of non-deformed poly(ethylene terephthalate) measured at various temperatures have been subjected to comparative analysis. There is no correlation between the results obtained by the different methods. The reason for this is shown to be the imperfections in the methods of determining the degree of crystallinity, which do not provide the true composition of the crystalline phase. Consideration has been paid to the validity of the main principles involved in the thermal method of determining the degree of crystallinity, so as to eliminate the imperfections in the existing methods and to provide the correct value of the mass of the crystalline phase. The phase composition of PET has been analyzed by the thermal method at different temperatures and conditions of crystallization. A marked difference from the literature data is observed in the range of low temperatures.

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Zusammenfassung Eine vergleichende Analyse der Literaturangaben bezüglich des bei verschiedenen Temperaturen gemessenen Kristallisationsgrades von nicht-deformiertem Poly(äthylen-terephthalat) wurde durchgeführt. Zwischen den mit verschiedenen Methoden erhaltenen Ergebnissen besteht keine Korrelation. Es wurde gezeigt, daß der Grund hierfür in der Unvollkommenheit der Methoden zur Bestimmung des Kristallisationsgrades liegt, da diese nicht die wahre Zusammensetzung der Kristallinen Phase angeben. Die Gültigkeit der wichtigsten Prinzipien, welche die thermische Bestimmung des Kristallisationsgrades unter Ausschaltung der Unvollkommenheit der bestehenden Methoden gewährleisten und den richtigen Wert der Masse der kristallinen Phase angeben, wurden in Erwägung gezogen. Die Analyse der Phasenzusammensetzung von PET wurde durch die thermische Methode bei verschiedenen Temperaturen und Kristallisationsbedingungen durchgeführt. Ein deutlicher Unterschied zu den Literaturangaben kann im Bereich der niedrigen Temperaturen beobachtet werden.

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