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1.
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.
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.

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.  相似文献   

2.
Summary The recently developed relativistic double perturbation theory is extended to handle relativistic changes of molecular structure more easily. This is achieved by simple coordinate scalings. Accurate higher order mixed perturbation energies for H 2 + are calculated. The relativistic changes of bond energy,DE, of bond length,R e , and especially of force constant,k, and of anharmonicity,a, are large, up to 100%·(Z/c)2. The dominant contributions tok anda are due to the indirect change of the nonrelativistick anda connected with the relativistic change of bond length. Accordingly the relativistic changes obey Badger's and Gordy's rules (–RDEk).Dedicated to Prof. Klaus Ruedenberg in appreciation of his fundamental contributions to both formal theory and physical explanations in quantum chemistry  相似文献   

3.
Glaser  Robert  Geresh  Shimona  Luria  Shlomo  Drouin  Marc  Michel  André 《Structural chemistry》1994,5(4):277-282
Hydrogenation ofZ-(–)-(1R, 3R, 4S)-menthyl 2-formamido-4,4,4-trifluoro-2-butenoate catalyzed by Pd/C was performed at atmospheric pressure to yield a mixture of (2R, 1R, 3R, 4S)- and (2S, 1R, 3R, 4S)-menthyl 2-formamido-4,4,4-trifluorobutanoate diastereomers in a 5545 ratio, respectively. Repeated fractional crystallization from ethyl acetate and vapor diffusion of petroleum ether afforded (+)–(2S, 1R, 3R, 4S)-menthyl 2-formamido-4,4,4-trifluorobutanoate as clear colorless, crystalline prisms which were subjected to single-crystal X-ray diffraction analysis. The crystals belong to the orthorhombic system P212121, and at 213 K:a=5.054(1),b= 10.000(2),c=32.707(1) Å,V=1652.9(4) Å3,Z=4,R(F)=0.040, andR w (F)=0.037. The finding of the (2S)-configuration for the formamido-acid portion of the (+)-ester enabled the configurational assignment of the asymmetric hydrogenation products ofZ-methyl 2-formamido-4, 4,4-trifluoro-2-butenoate catalyzed by chiral diphosphine/rhodium(I) complexes.  相似文献   

4.
In neutral and alkaline solutions, tetrakis(4-carboxyphenyl)porphyrin (TCPP) and tetrakis(4-sulfonatophenyl)porphyrin (TSPP) form 1:1 and 2:1 host–guest inclusion complexes with -cyclodextrin (-CD), -cyclodextrin (-CD), and 6-deoxy-6-diethylamino--CD (DEA--CD), except for DEA--CD in alkaline solution. On the other hand, TCPP and TSPP form only 1:1 inclusion complexes with 6-deoxy-6-dihexylamino--CD (DHA--CD). The limited solubilities of DEA--CD in alkaline solution and DHA--CD are likely responsible for no observation of the 2:1 inclusion complex containing DEA--CD in alkaline solution and that containing DHA--CD. The equilibrium constants (Ks) of TCPP and TSPP for the formation of the inclusion complexes have been estimated from the absorption and/or fluorescence intensity changes in neutral and alkaline solutions. The K2 values, which are the equilibrium constants for the formation of the 2:1 host–guest inclusion complex from the 1:1 inclusion complex, are about one tenth the corresponding K1 values, except for the -CD–TSPP system in alkaline solution. In neutral solution, where DEA--CD and DHA--CD are in protonated forms, the electrostatic force operates between DEA--CD (DHA--CD) and TCPP (TSPP), leading to the greater K values than those in alkaline solution, where DEA--CD and DHA--CD exist as neutral species.  相似文献   

5.
Summary The identification of small amounts of sugars by their X-ray powder diagrams is suggested as a most simple and practical method in routine analysis.It is especially valuable in working with minute amounts of material, and has proved very useful for the final identification of chromatographically-separated sugars.The characteristics of the powder diagrams of a number of monosaccharides of special interest to the physiological chemist are reported in detail. The substances thus investigated are- and-D-glucose and-glucose monohydrate,- and-D-galactose,- and-D-mannose,D-fructose,D-glucuronolactone,- and-D-glucosamine hydrochloride,- and-D-galactosamine (chondrosamine) hydrochloride,-L-fucose, andD-ribose. For various reasons arabinose, lyxose, and xylose have also been included.It is clear from the powder diagrams of the galactoses that the crystalstructure earlier ascribed to-galactose is that of-galactose.A single-crystal study of-glucosamine hydrochloride was carried out by theWeissenberg technique. The crystal-dimensions obtained agree with those earlier found byCox et al5, 7.The optical rotation of chondrosamine hydrochloride was found to be [] D 20° = - 135° - 93° - 39°, the first value being considerably higher than that given for the-form byLevene. A method for the preparation of-mannose is described.
Zusammenfassung Die Identifizierung kleiner Mengen verschiedener Zuckerarten mit Hilfe ihrer Röntgen-Pulverdiagramme wird als einfache und praktische Routinemethode vorgeschlagen.Diese Methode ist besonders wertvoll, wenn nur kleine Substanzmengen zur Verfügung stehen, und hat sich für die endgültige Identifizierung von chromatographisch getrennten Zuckern als sehr geeignet erwiesen.Die Einzelheiten der Pulverdiagramme folgender physiologisch-chemisch bedeutungsvoller Monosaccharide werden mitgeteilt:- und-D-Glukose und Glukosehydrat,- und-D-Galaktose,- und-D-Mannose,D-Fruktose,D-Glukuronolakton,- und-D-Glukosaminhydrochlorid,- und-D-Galaktosamin-(Chondrosamin)-hydrochlorid,-L-Fukose, dieD-Pentosen Arabinose, Lyxose, Ribose und Xylose.Aus den Pulverdiagrammen der Galaktosen geht deutlich hervor, daß die Krystallstruktur, die früher der-Galaktose zugeschrieben wurde, tatsächlich diejenige der-Form ist.Die Untersuchung eines Einzelkristalles von-Glukosaminhydrochlorid wurde nach derWeissenberg-Technik ausgeführt. Die erhaltenen Werte stimmen mit den früher vonCox und Mitarbeitern gefundenen überein.Die optische Drehung des Chondrosaminhydrochlorids wurde zu [] D 20° = + 135° + 93° + 39° gefunden. Der erstgenannte Wert ist größer als der entsprechende, vonLevene angegebene Drehungswert.Eine Methode zur Darstellung von-Mannose wird beschrieben.

Résumé On propose une méthode de routine simple et pratique pour l'identification de petites quantités de divers sucres au moyen de leur diagramme de poudres aux rayons X. Cette méthode est particulièrement précieuse quand on n'a que de petites quantités de matière à sa disposition et elle s'est montrée très convenable pour l'identification finale de sucres séparés par chromatographie. Des particularités des diagrammes de poudres des monosaccharides suivants intéressent le chimiste physiologiste: et-D-glucose et hydrate de glucose, et-D-galactose, et-D-mannose, D-fructose,D-glucuronolactone, chlorhydrate d' et-D-glucosamine, chlorhydrate d' et-D-galactosamine (chondrosamine), l'-L-fucose, lesD-pentoses, l'arabinose, le lyxose, le ribose, le xylose. Des diagrammes de poudres des galactoses découle clairement le fait que la structure cristalline qui fut attribuée précédemment à l'-galactose est celle de la forme. L'expérience sur un cristal unique de chlorhydrate d'-glucosamine a été effectuée d'après la technique deWeissenberg. Les valeurs obtenues concordent avec celles trouvées précédemment parCox et ses collaborateurs. Le pouvoir rotatoire du chlorhydrate de chondrosamine a été trouvé égal à D 20 = + 135° + 93° + 39°. La première valeur est plus grande que celle donnée parLevene. On décrit une préparation de l'-mannose.


With 3 figures.  相似文献   

6.
The contact angle,, formed by a liquid on a solid surface in air depends on the solid-air ( S ), liquid-air ( L ) and solid-liquid ( SL ) interfacial free energies, as described by Young's equation. Critical examination of reported contact angles for numerous liquids and solids leads to an empirical correlation between sL and both Y and S . Combination of this correlation with Young's equation gives an empirical relation allowing calculation of S from L and Calculations made with these empirical relations agree well with estimations of S obtained by the method of critical spreading, and are consistent with Young's equation.Founded and supported by F. Hoffmann-La Roche and Co., Limited Company, Basel, Switzerland.  相似文献   

7.
A study is made of the reaction of the sodium and ammonium salts of 1 -alkyl- and 1, 2-dialkyl-4-nitro-5 mercaptoimidazoles with -halogenoketones, -halogenoalcohols, and — and -halogeno acids, to give a number of 1 -alkyl- and 1, 2-dialkyl-4-nitro-5- [-ketoalkyl (aralkyl)-, -hydroxyethyl-, and -and -carboxyalkyl] mercaptoimidazoles.For Part XXIV see [6].  相似文献   

8.
Interaction of quantum system S a described by the generalised × eigenvalue equation A| s =E s S a | s (s=1,...,) with quantum system S b described by the generalised n×n eigenvalue equation B| i = i S b | i (i=1,...,n) is considered. With the system S a is associated -dimensional space X a and with the system S b is associated an n-dimensional space X n b that is orthogonal to X a . Combined system S is described by the generalised (+n)×(+n) eigenvalue equation [A+B+V]| k = k [S a +S b +P]| k (k=1,...,n+) where operators V and P represent interaction between those two systems. All operators are Hermitian, while operators S a ,S b and S=S a +S b +P are, in addition, positive definite. It is shown that each eigenvalue k i of the combined system is the eigenvalue of the × eigenvalue equation . Operator in this equation is expressed in terms of the eigenvalues i of the system S b and in terms of matrix elements s |V| i and s |P| i where vectors | s form a base in X a . Eigenstate | k a of this equation is the projection of the eigenstate | k of the combined system on the space X a . Projection | k b of | k on the space X n b is given by | k b =( k S b B)–1(V k P})| k a where ( k S b B)–1 is inverse of ( k S b B) in X n b . Hence, if the solution to the system S b is known, one can obtain all eigenvalues k i } and all the corresponding eigenstates | k of the combined system as a solution of the above × eigenvalue equation that refers to the system S a alone. Slightly more complicated expressions are obtained for the eigenvalues k i } and the corresponding eigenstates, provided such eigenvalues and eigenstates exist.  相似文献   

9.
Unicyclic Graphs with Minimal Energy   总被引:7,自引:0,他引:7  
If G is a graph and 1,2,..., n are its eigenvalues, then the energy of G is defined as E(G)=|1|+|2|++| n |. Let S n 3 be the graph obtained from the star graph with n vertices by adding an edge. In this paper we prove that S n 3 is the unique minimal energy graph among all unicyclic graphs with n vertices (n6).  相似文献   

10.
The vertical valence ionization potentials of cyclopropane, ethylene oxide and ethylene imine are calculated by a many-body Green's function method. For C3H6 the ordering of the ionization potentials is 2e(), 1e(), 2a1(), 1a2(), 1e(). The assignment of the 2a1 and the 1a2 ionization potentials which has been controversial is thus clarified. The ordering is in agreement with the result obtained via Koopmans' theorem. For ethylene oxide and ethylene imine Koopmans' theorem fails in predicting the correct order of ionic states. For C2H4O the ordering of the ionization potentials is 2b 1(), 4a 1, 1a 2(), 2b 2,3a 1, 1b 1(), 1b 2, 2a 1 and for C2H5N 6a, 5a, 3a, 2a, 4a, 3a, 1a, 2a. The agreement of the computed ionization potentials with the experimental values is very satisfactory.  相似文献   

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