Die multikomponenten Formen von Cellulase (EC 3.2.1.4) ausAspergillus oryzae

The enzyme cellulase fromAspergillus oryzae was resolved into four multiple forms, using anion exchange chromatography on DEAE Sephadex A-50 and gel filtration on Sephadex G-75. The stages of fractionation were followed by electrophoresis on cellulose acetate strips. These enzyme forms are characterized by different enzyme activities and isoelectric points.

Herrn Univ.-Prof. Dr.Hans Tuppy zum 65. Geburtstag herzlichst gewidmet.     

Reactions with hydrazidoyl halides. IV. Synthesis of thiazolo[3,2-a]benzimidazoles,imidazo[2,1-6]thiazoles and pyrazolo[4,3-b]thiazines

Hydrazidoyl halides were condensed with 2-mercaptobenzimidazole yielding 4a-c and 7a,b which were cyclized to the corresponding 2-arylhydrazonothiazolo[3,2-a]benzimidazol-3-ones 5a,b and 3-substituted 2-arylazo thiazolo[3,2-a]benzimidazoles 8a,b respectively. Imidazo[2,1-b]thiazoles were obtained by the reaction of hydrazidoyl halides with 2-mercapto-4,5-dihydroimidazole. Also, hydrazidoyl halides 6a,b were reacted with 3-amino-4-mercapto-5-phenylpyrazole to give pyrazolo[4,3-b]thiazines 15a,b . The structures of the products were assigned on the basis of their elemental analysis and spectral data.     

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.

---

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.     

Synthesis of Triazolyl-Oxadiazolyl-Thiazolyl- and Thiadiazolylbenzofuran of Potential Biological Activity

4,7-Dimethoxy ( Ia ) and 4-methoxy ( Ib ) 6-hydroxybenzofuran-5-carbohydrazide were reacted with aryl or alkyl isothiocyanates to give the corresponding thiosemicarbazides ( IIa-h ). Cyclization of the substituted thiosemicarbazides with sodium hydroxide led to the formation of 1,3,4-triazol-2-yl-benzofuran derivatives ( IIIa-d ). Desulfurization of thiosemicarbazide by mercuric oxide gave 1,3,4-oxadiazolyl-benzofuran ( IVa-c ). Treatment of thiosemicarbazide with ethyl bromo-acetate or f -bromopropionic acid yielded 4-thiazolidin-2-yl-carbonyl-benzofuran ( Va-h ). The reaction of compounds IIb , e , f with sulphuric acid or phosphorus oxychloride gave 1,3,4-thiadiazol-2-yl-benzofuran ( VIa-d , VII ).     

Synthesis and Inhibitory Activity Against Epstein-Barr Virus of Some New 1,2,3,4-Tetrahydropyrimidine-2-thiones

1,2,3,4-Tetrahydropyrimidine-2-thiones 4a–n were synthesized through the reaction of aromatic aldehydes 1a–n , ethyl acetoacetate (2) and thiourea ( 3) . The structures of all newly synthesized heterocyclic compounds elucidated by the use of IR, ¹H NMR, mass spectra, and elemental analyses. The inhibitory activity against the Epstein-Barr Virus early antigen (EBA-VA) of all newly synthesized heterocyclic compounds were evaluated.     

Synthesis of Heterocycles via 2-Thioxo-1,2-dihydropyridine-3-carbonitrile Derivative

The present study aimed to investigate the synthetic potentiality and chemical reactivity of 2-thioxo-1,2-dihydropyridine-3-carbonitrile derivative 1. This goal performed via its reaction with each of 1-chloroacetone and iodomethane to afford the corresponding 2-alkylthio derivatives 3 and 9, respectively. Compound 3 underwent intramolecular cyclization to afford the corresponding thieno[2,3-b]pyridine derivative 4 which in turn, reacted with dimethylformamide/dimethylacetal followed by hydrazine hydrate and nitrous acid to afford the corresponding pyridothienopyrimidine and pyridothienopyridazine derivatives 6 and 8, respectively. On the other hand, Compound 9 reacted with hydrazine hydrate to give 3-aminopyrazolo[3,4-b]pyridine derivative 10, which diazotized with nitrous acid to give the corresponding diazonium salt 11. Compound 11 coupled with several active –CH₂-containing reagents to synthesize the corresponding pyridopyrazolo-triazines 15, 24, 29, and 31. The formulas of all newly synthesized heterocyclic compounds were elucidated by considering the data of IR, ¹H NMR, Mass spectral data, as well as data from elemental analyses.     

Kinetic and mechanistic investigations on the oxidation of N’-heteroaryl unsymmetrical formamidines by permanganate in aqueous alkaline medium

Kinetic studies on the oxidation of two substituted azinyl formamidines (Azn-Fs), namely N,N-dimethyl-N’-(pyrimidin-2-yl) formamidine (Pym-F) and N,N-dimethyl-N’-(pyridin-2-yl) formamidine (Py-F), by alkaline permanganate have been performed by spectrophotometry. The spectroscopic and kinetic evidence reveals the formation of 1:1 intermediate complexes between the oxidant and substrates. The influence of pH on the oxidation rates indicated that the reactions are base-catalyzed. The reactions show identical kinetics, being first order each in [MnO₄ ^?]₀ and [Azn-F]₀, but with a fractional first-order dependence on [OH^?]. The effect of temperature on the reaction rate has been studied. Increasing ionic strength has no significant effect on the rate. The final oxidation products of Pym-F and Py-F were identified as 2-aminopyrimidine and 2-aminopyridine, respectively, in addition to dimethyl amine and carbon dioxide. Under comparable experimental conditions, the oxidation rate of Py-F is higher than that of Pym-F. A reaction mechanism adequately describing the observed kinetic behavior is proposed, and the reaction constants involved in the different steps of the mechanism have been evaluated. The activation parameters with respect to the rate-limiting step of the reactions, along with thermodynamic quantities, are presented and discussed.     

Order and type of basic sets of polynomials associated with functions of algebraic semi block matrices

§ 1 is an introduction to basic sets of polynomials and to algebraic infinite matrices. In § 2 we investigate the order of basic sets associated with functions of algebraic semi block matrices whose elements are of a certain order of magnitude. In § 3 we investigate the type of such basic sets.     

The Sextic Centrifugal Distortion Terms for an Open-Shell Complex Consisting of a Diatomic Molecule in a (2S+1)Sigma Electronic State and a Closed-Shell Partner

An effective Hamiltonian for calculating rotational energy levels of an open-shell diatomic molecule, in a (2S+1)Sigma electronic state, weakly bonded to a closed-shell partner was presented (W. M. Fawzy, J. Mol. Spectrosc. 191, 68-80 (1998)). The Hamiltonian was given as H = H(ev) + H(rot) + H(sr) + H(ss) + H(cd) + H(srcd) + H(sscd), where all the quartic centrifugal distortion correction terms were included in the Hamiltonian term H(cd) but the sextic centrifugal distortion terms were ignored. This Hamiltonian is useful in cases where the complex has a well-defined equilibrium geometry and if the barrier to large-amplitude motion is large compared to the rotational constant of both the closed-shell molecule and its paramagnetic partner; if the barrier to large-amplitude motion is small compared to the rotational constant of one or both of the fragments, then a different treatment is required. In this paper, we introduce the new Hamiltonian terms H(sex(A))(cd) and H(sex(S))(cd), which represent the sextic centrifugal distortion correction terms for an asymmetric rotor. We also introduce all the nonvanishing matrix elements of each of the H(sex(A))(cd) and H(sex(S))(cd) operators. These operators and their matrix elements are required for calculating the rotational energy levels of relatively high J values in the described type of weakly bonded open-shell complexes. The terms H(sex(A))(cd) and H(sex(S))(cd) and their matrix elements are also valid for any stable asymmetric rotor in a nondegenerate electronic state. A brief discussion of the new Hamiltonian terms and their matrix elements is given. Copyright 2000 Academic Press.     

Abeliaside,a new phenolic glucoside from Abelia triflora

A new phenolic glucoside, abeliaside, along with four known compounds, 5,6,7,4′-tetrahydroxy flavones, caffeic acid, 4-O-caffeoylquinic acid and caffeic acid glucoside, was isolated from the leaves of Abelia triflora R. Br. (Caprifoliaceae). The structure of the new compound was elucidated by different spectroscopic techniques. Compounds 1–5 were assayed for their anticancer activities against two cancerous human cell lines, MCF-7 and PC-3 cells, and normal Vero cell line using the crystal violet staining method. From the results it could be seen that caffeic acid possessed the highest anticancer effect against MCF-7 (IC₅₀: 17 μg/mL) and PC-3 (IC₅₀: 20.1 μg/mL) compared to vinblastine sulphate as reference drug (IC₅₀: 4.6, 2.8 μg/mL). The other compounds showed weak anticancer activity on both cell lines.