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  • 1
    Electronic Resource
    Electronic Resource
    Structured bienzymatical models formed by sequential enzymes bound into artificial supports: Active glucose transport effect (1972)
    Springer
    The journal of membrane biology 8 (1972), S. 313-332 
    Details
    ISSN: 1432-1424
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Two different artificial membrane systems bearing two built-in sequential enzymes are studied and compared in this communication. The first is a nonstructured membrane bearing two mixed enzymes: β-galactosidase and glucose-oxidase. Its use enables a mathematical model to be formulated describing the heterogeneous phase kinetics of a bienzymatic system. The second is a multi-layer membrane system in which the structural dissymmetry involves a spatial orientation of the reacting metabolites, resulting in active glucose transport. The latter system consists of two active leaflets, the first phosphorylating glucose (hexokinase+ATP), the second dephosphorylating glucose-6 phosphate (phosphatase). On either side of this system, a perm-selective proteic layer allows the passage of glucose but not of glucose-6 phosphate. When positioned between two compartments containing glucose, such a membrane accumulates glucose on its phosphatase side, while degrading ATP. The accumulation of glucose as a function of the initial concentration shows the classical saturation of the transport system. Fructose competes with glucose transport. The chemical balance of these two reactions has the appearance of hydrolysis of ATP. Vectorial catalysis is a result of the dissymmetry in distribution of active sites and can be explained by an oscillatory concentration profile of glucose inside the membrane. The bienzymatic mechanism, a model of which is given here, is valid for any thickness of active layers and applicable to a system where both active sides are part of the same molecule as soon as it forms a uniformly oriented monolayer throughout the membrane structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01868108
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  • 2
    Electronic Resource
    Electronic Resource
    Optically active diamide as a model for studying interactions between mineral salts and nylon type polyamides in methanol solutions (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 12 (1974), S. 851-863 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: N,N′-Dicaproyl (-)1,2-diaminopropane (I) was used as a convenient model for the study of the optical activity of a nylon type polyamide: polysebacamide (-)1,2-diaminopropane (II). ORD of I was measured in different solvents. A peculiar behavior is observed in methanol in the presence of mineral salts. The influence of 0.1M potassium salts (Cl-, Br-, SCN-, NO3-, SO4-2) and 0.1M alkaline chlorides and alkaline earth chloride hexahydrates on the optical activity of I in methanol are described. Alkaline salts and MgCl2 give approximately the same effect: there is a decrease of the rotations without change of sign. SrCl2 and CaCl2 shift ORD curves towards the negative rotations, the last one giving complete inversion. This inversion is directly related to the CaCl2 concentration and is attributed to adduct formation between amide groups and salt. Assuming that the different species are at equilibrium, an apparent equilibrium constant is obtained from the optical rotations for a complex of one mole of CaCl2 with one mole of I. Results are used to discuss the complex ORD of poly(-) 1,2-diaminopropane sebacamide in methanol saturated with CaCl2.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1974.170120415
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  • 3
    Electronic Resource
    Electronic Resource
    Effect of nonelectrostatic interactions on the macromolecular behavior of polyelectrolytes. I. Potentiometric titrations of PLL in water and aqueous-organic mixtures (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 12 (1974), S. 2659-2670 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The potentiometric and viscosity behavior of salt-free solutions of the polycondensate between L-lysine and 1,3-benzenedisulfonyl chloride (PLL) and related polyelectrolytes, have been investigated in water and in aqueous-organic mixtures (acetone-water). The effects of counterions and solvent on the pH-induced conformational transition is related to hydrophobic interactions. The transition from a compact state to a more extended one shifts towards high values of neutralization with increasing length of N-tetraalkylammonium counterions. Moreover, the above transition gradually disappears as the percentage of acetone in the mixture is increased, which is interpreted as reflecting the breakdown of the compact structure due to hydrophobic interactions stabilized by bulky counterions. A linear decrease in the free energy variation ΔGt° is observed with increasing percentage of acetone up to about 40% of acetone, and a value of 1200 cal/unit is obtained for PLL in water, which is a reasonable value compared to other data for hydrophobic polyelectrolytes.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1974.170121120
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  • 4
    Electronic Resource
    Electronic Resource
    Effect of nonelectrostatic interactions on the macromolecular behavior of polyelectrolyes. II. Influence of urea and dyes on the viscometric and optical behavior of PLL (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 12 (1974), S. 2671-2682 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of urea and of dyes on the viscometric behavior of aqueous solutions of PLL has been investigated. The compact structure, which is characteristic of PLL in pure water, is found to disappear progressively as the amount of urea is increased. This is interpreted as due to the destruction in such media of nonelectrostatic interactions responsible for the stabilization of the compact structure of PLL in pure water. In 8M urea, the macromolecular behavior of PLL during the ionization is dependent only on the repulsive interactions between the charged groups. The extension of PLL is then practically independent of the nature of counterions, contrary to what was observed in pure water. In the presence of dye (acridine orange), the compact form of PLL is stabilized, and the dye is found to bind for the two structures of PLL. The analogy between the behavior of Bu4N+ and that of dye is in agreement with the fact the Bu4N+ leads to a stabilization of the compact structure by way of specific interactions between N-tetraalkylammonium counterions and the PLL chain through the structure of water. The hydrodynamic behavior of PLL is in good agreement with data obtained from potentiometric and optical activity measurements.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1974.170121121
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  • 5
    Electronic Resource
    Electronic Resource
    Conformational transition of poly(methacrylic acid) in methanol-water mixtures (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 12 (1974), S. 2767-2778 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of ionization on the potentiometric and viscometric behavior of both poly(methacrylic acid) (PMA) and poly(acrylic acid) (PAA) was investigated in methanol-water mixtures. The potentiometric and viscosity data revealed that the conformational change which takes place for PMA in water gradually disappears with increasing content of methanol in methanol-water mixtures. For mixtures containing 40 and 50% methanol, the behavior of PMA solutions becomes similar to that of PAA, i.e., the discontinuity versus the degree of ionization is no longer detectable and the molecule unfolds regularly upon ionization. The addition of methanol leads to the breakdown of the compact structure of PMA which is stabilized, at low degree of ionization in water, by nonelectrostatic interactions between the methyl groups of PMA.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1974.170121206
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  • 6
    Electronic Resource
    Electronic Resource
    Study of stereoregularity of poly(vinyl ketone)s by proton nuclear magnetic resonancePart of the thesis of L. Merle. (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 709-728 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Zwei Poly(vinylketone), Poly(methylvinylketon) (PMVK) und Poly(phenylvinylketon) (PPVK) werden isotaktisch synthetisiert. Die 1H-NMR Spektren dieser Polymeren und der meso- und racemischen Modell-Dimeren ermöglichen die Ermittlung des Anteils isotaktischer Diaden aus der Fläche der Peaks der kettenständigen, nichtäquivalenten β-Methylenprotonen (HA und HB). Die Differenz zwischen den chemischen Verschiebungen der HA und HB Protonen ist bei beiden Polymeren (isotaktischem PMVK und isotaktischem PPVK) mit etwa 0,8 ppm außergewöhnlich groß. Die Kopplungskonstanten und die Frequenzen der β-CH2- und der α-CH-Gruppen wurden unter Anwendung des ABX2-Systems bestimmt.Es wird eine spontane Epimerisierung des isotaktischen PPVK gefunden, die stets von einem Abbau begleitet ist. Dies führt zu dem Schluß einer gleichzeitigen photochemischen Reaktion vom Typ Norrish II.
    Notes: Two poly(vinyl ketone)s, poly(methyl vinyl ketone) (PMVK) and poly(phenyl vinyl ketone) (PPVK), are isotacticly synthesized. The 1H-NMR spectra of these polymers and of the meso and racemic model dimers help to determine the percentage of isotactic dyads using the area of the peaks of the non equivalent protons (HA and HB) of the β-methylene group of the chain. The difference between the chemical shifts of the HB and HB protons is exceptionally large (approximately 0,8 ppm for both isotactic PMVK and isotactic PPVK). The coupling constants and the β-CH2 and the α-CH groups' frequencies are determined by applying the ABX2 system.A spontaneous epimerization of isotactic PPVK is found; this is always accompanied by a degradation and leads to the assumption of a simultaneous photochemical reaction of the Norrish II type.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760314
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  • 7
    Electronic Resource
    Electronic Resource
    Polymères optiquement actifs. XI. Polycondensats formophénoliques de la N-benzoyl L-tyrosine (TyB) et de la N-p-hydroxyphénylsulfonyl L-phénylalanine (phhps). synthèse et activité optique (1973)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 165 (1973), S. 17-29 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die in der Überschrift genannten Polymeren wurden durch Kondensation von Formaldehyd mit optisch aktiven, Phenolgruppen tragenden Monomeren, N-benzoyl L-tyrosine (TyB) et N-(p-Hydroxyphenylsulfonyl)-L-phenylalanin (PhHPS), in saurer (Pa) und basischer (Pb) Lösung hergestellt. Ihre chemische Zusammensetzung wurde anhand der IR-Spektren, des Molekulargewichts eines Grundbausteins (Mr) und durch Vergleich mit anderen Polykondensaten des gleichen Typs untersucht. PaTyB, PbTyB und PbPhHPS haben die zu erwartende Struktur, beim PaPhHPS hingegen tritt eine weitere Reaktion ein, die aufgeklärt wird. Die Drehwerte von PaTyB und PbTyB hängen vom Reaktionsmilieu der Polykondensation ab und ändern sich mit dem Lösungsmittel. Die Unterschiede verschwinden nur in 0,1 molarer Kalilauge in Gegenwart von hohen Konzentrationen an Salzen (KCl, LiBr). Der Einfluß von Wasser in Dioxan und von Salzen in 0,1 molarer Kalilauge wird mit Hilfe der Rotationsdispersion (DRO) untersucht. Die nachgewiesenen, negativen Drehwertsbeiträge werden schwachen Bindungen zwischen den Aminogruppen im Polymeren und Wasser, KCl und LiBr zugeordnet.
    Notes: Les polymères du titre sont préparés par polycondensation en milieu acide (Pa) et en milieu alcalin (Pb) du formaldéhyde avec les monomères phénoliques optiquement actifs N-benzoyl L-tyrosine (TyB) et N-(p-hydroxyphénylsulfonyl)-L-phénylalanine (PhHPS). Leurs compositions chimiques sont vérifiées à partir des spectres IR, de la masse (Mr) du motif monomère et de la comparaison avec d'autres polycondensats du même type. PaTyB, PbTyB et PbPhHPS ont la structure chimique attendue, par contre, PaPhHPS fait l'objet d'une réaction secondaire qui est identifiée. Les pouvoirs rotatoires de PaTyB et PbTyB dépendent du milieu de polycondensation. L'ècart varie d'un solvant à l'autre. II ne s'annule que dans la potasse 0,l M en presence de fortes concentrations de sels (KCl, LiBr). L'influence de l'eau dans le dioxanne et des sels dans la potasse 0,l M est étudiée par dispersion rotatoire (DRO). Les contributions de DRO partielles negatives mises en évidence sont attribuées des espèces chimiques labiles entre les groupes amide portés par les motifs monomères et le co-soluté (H2O, KCI, LiBr).
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1973.021650103
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  • 8
    Electronic Resource
    Electronic Resource
    Polymerization of oxiranylalkylamines and thiiranylalkylamines derived from achiral and racemic secondary amines (1973)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 170 (1973), S. 23-37 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Bei der durch Zn(C2H5)2/H2O, Zn(C2H5)2/CH3OH, Al(C2H5)3/H2O und andere Systeme initiierten Polymerisation von N,N-Diäthyl-N-(oxiran-2-ylmethyl)amin (Ia) erhält man nur niedermolekulare polymere in geringer Ausbeute. Das entsprechende Thiiranderivat N,N-diäthyl-N-(thiiran-2-ylmethyl)amin (IIa), gibt mit demselben Initiator Hochpolymere, die nicht kristallin sind, im Gegensatz zu Propylensulfid. Physikalisch-chemische Eigen-schaften (UV-, IR-Spektren, Neutralisation und Gelbindung bei der Neutralisation) wurden untersucht. Höhere Homologe von IIa, die sich von racemischen sec-Aminen R1R2NH ableiten, werden synthetisiert und mit Zn(C2H5)2/H2O polymerisiert. Der Einfluß von R1 und R2 auf die physikalischen und chemischen Eigenschaften der Polymeren wird diskutiert.
    Notes: The polymerization of N,N-diethyl-N-(oxirane-2-ylmethyl)amine (Ia), by initiator systems such as ZnEt2/H2O, ZnEt2/CH3OH, AlEt3/H2O, and others, gives only low molecular weight polymers with low yields. The corresponding thiirane derivative, N,N-diethyl-N-(thiirane-2-yl-methyl)amine (IIa), with the same type of initiators gives high molecular weight polymers which are non-crystalline contrary to the case of propylene sulfide. Physicochemical properties (UV and IR absorptions, neutralization and gelation during neutralization) of these polymers are studied. Higher homologues of IIa derived from racemic secondary amines R1R2NH are synthesized and polymerized with ZnEt2/H2O. The influence of the substitu ents R1 and R2 on the physical and chemical properties of the polymers is discussed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1973.021700103
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  • 9
    Electronic Resource
    Electronic Resource
    Enzyme-synthetic polyampholyte systems (1986)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 187 (1986), S. 211-221 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polyampholytes, prepared by copolymerization of 2-(N,N-dimethylamino)ethyl methacrylate and methacrylic acid, increase the urease activity over a large pH range, when the acid content is between 24 and 68 mol-%, while the activity of the enzyme is inhibited by polyampholytes having more than 84 mol-% of methacrylic acid groups. The enzyme reaction induces conformational changes of the polyampholyte chain resulting from a pH increase due to the formation of ammonium carbonate. The contraction of the macromolecule was followed by viscometry and by the volume change of a cross-linked analogous polyampholyte gel.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1986.021870120
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  • 10
    Electronic Resource
    Electronic Resource
    Reduction of poly(vinyl ketone)s into secondary poly(allyl alcohol)s (1973)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 172 (1973), S. 115-125 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Verschiedene Poly(vinylketone) mit R = Alkyl oder Phenyl, wurden mit Lithiumaluminiumhydrid oder Kaliumtetrahydroborat reduziert.Die Einflüsse des Substituenten R, der Art und Menge des Hydrids und der Reaktionsdauer auf den Reduktionsgrad werden beschrieben. Aminoderivate der Polyalkohole werden dargestellt.
    Notes: Different poly(vinyl ketone)s in which R is an alkyl or phenyl radical were reduced by lithium aluminum hydride or by potassium tetrahydroborate.The influences of the substituent R, of the nature and quantity of the hydride, and of the duration of the reaction on the degree of reduction are described. Amine derivatives of the polyalcohols are prepared.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1973.021720110
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