摘要:

AbstractA new water‐soluble acrylic polymer5, with spacer‐arms bearing benzamidine groups, was synthesized as a polymeric inhibitor to protect trypsin during immobilization of this enzyme on two different water‐insoluble carriers, i.e., VINAC‐S and ACAPROSUC. The latter is an acrylic polymer and bears sidechains ending with succinimido ester groups, whereas VINAC‐S is a polyvinylic matrix having aldehyde groups. The trypsin‐VINAC‐S conjugates prepared in the presence of the polymeric inhibitor5were twice as active towardsN2‐benzoyl‐L‐arginine ethyl ester, and four times as active towards haemoglobin, as the corresponding conjugates prepared in the absence of5. More than 80% of the overall initial esterolytic activity of trypsin was retained by the corresponding ACAPROSUC conjugate, when the immobilization reaction was carried out in the presence of5. The overall residual activity of the conjugate was 46% when operating in the absence of5. The above method of enzyme protection should prove very useful in immobilized enzyme methodo

ISSN:0025-116X    

DOI:10.1002/macp.1981.021820601

出版商:Hüthig&Wepf Verlag    

年代:1981

数据来源: WILEY

摘要:

AbstractL‐LeucineN‐carboxyanhydride was polymerized inN,N‐dimethylformamide (DMF) or 1,4‐dioxane (DIO) at 25°C with either 1,6‐hexanediamine (1) or its monocarbamate2using a constant volume apparatus, initially filled with nitrogen or carbon dioxide. Number average molar masses from amino end group titrations on one hand and from initial monomer/initiator ratios and conversions on the other were practically identical for monomer conversions between 25 and 79%, indicating both the living nature of the polymerization and a participation of all initially present amino groups, despite the fact that polymer precipitation was observed at higher conversions for all systems and an additional precipitation of the carbonate2for the system1/DIO/CO2at low conversions. Two kinetic stages were observed for the latter system, but three kinetic stages for all other ones. The absence of a rapid initial polymerization period for the system,1/DIO/CO2as contrasted to the high initial rates for the systems1/DMF/CO2or1/DMF/N2points towards a carbamate mechanism in the first case and an amine mechanism in the second. The relation between intrinsic viscosities and number average molar masses of poly(L‐leucine) in trifluoroacetic acid at 25°C was found as [η] = 0,0169 〈M

ISSN:0025-116X    

DOI:10.1002/macp.1981.021820602

出版商:Hüthig&Wepf Verlag    

年代:1981

数据来源: WILEY

摘要:

AbstractL‐,D‐, and variousD,L‐phenylalanineN‐carboxyanhydrides (NCA's) were polymerized with benzylamine and various concentrations ofN‐methylbenzylamine, respectively, inN,N‐diethylformamide at 25°C. Three kinetic stages were observed for all systems: a fast “initiation” stage (I) followed by a slower stage (II) and a faster pseudo‐first order propagation stage (III). The initiation rate is higher forN‐methylbenzylamine than for benzylamine. The propagation rate constants,kpL, of the stage II polymerization of the L‐monomer are independent of initiator type and concentration, whereas the corresponding stage III rate constants vary with the initial monomer/initiator ratio. For each propagation stage, the ratios of rate constants,kpD,L/kpLandkpD,L/kpD, respectively follow the pattern predicted by the absence of crossover reactions. Molar masses calculated from monomer conversion are higher than those determined from amine end group concentration forN‐methylbenzylamine initiated polymerizations, but lower for be

ISSN:0025-116X    

DOI:10.1002/macp.1981.021820603

出版商:Hüthig&Wepf Verlag    

年代:1981

数据来源: WILEY

摘要:

AbstractSoluble hydrophillc polyaldehydes can be used as linking and crosslinking reagents for the modification and immobilization of proteins. An imine bond (or possibly an α‐hydroxyamino bond) between NH2functions of proteins or matrices and the aldehyde functions of the soluble polymer is formed under mild conditions. The polyaldehydes used were HIO4‐oxidized soluble polysaccharides of different degrees of oxidation, and the NH2matrices were Enzacryl AA and Enzacryl AH (for reference purposes also aminohexylcellulose), macroporous copolymer of glycidyl methacrylate reacted with ammonia, and nylon 6 and Estapor latices both with surface amino groups. Dextrans and Zulkowski starch were readily oxidized with HIO4, the degree of oxidation being determined by means of a modified photometric aldehyde determination method. As regards the reaction of the matrices with the polyoxidized polysaccharides (“glycosidation of the matrix”), it was found that 20 h incubation at 20°C and phosphate buffer pH = 6 furnished good results. In the investigations discussed in the present paper, relatively large quantities of polysaccharide were used for incubation, in order to achieve a high degree of glycosidation. For a closer analysis of matrices, several methods for the determination of the NH2concentrations on matrices were examined; in this case the reaction with pentafluorobenzaldehyde in aqueous phase followed by fluoride‐analysis furnished well reproduci

ISSN:0025-116X    

DOI:10.1002/macp.1981.021820604

出版商:Hüthig&Wepf Verlag    

年代:1981

数据来源: WILEY

摘要:

AbstractThe interaction of poly(L‐glutamic acid) with 3,6‐dioxaoctamethylenediamine was studied by circular dichroism spectroscopy under different conditions. In aqueous solution at pH 5,6 and in aqueous 1,4‐dioxane (30–50 vol.‐%) at pH 7,3 the conformation of poly(L‐glutamic acid) was completely changed from α‐helical to random coil in the presence of an excess

ISSN:0025-116X    

DOI:10.1002/macp.1981.021820605

出版商:Hüthig&Wepf Verlag    

年代:1981

数据来源: WILEY

摘要:

AbstractStrips of amorphous cellulose film were conditioned under wet atmospheres of 80 and 100% relative humidity or heated at 393 Kin vacuofor different time intervals. The structural change of these samples was investigated using differential scanning calorimetry (DSC), IR spectrometry, x‐ray diffractometry (x‐ray), and the density‐gradient column method. In the initial stage of conditioning of cellulose samples at a wet atmosphere, it was found that the thermally determined relative volume fraction (α) of the amorphous part of cellulose stays constant while the diffusion coefficient (Dod), calculated from the rate of H → D exchange of OH groups observed in IR, decreases rapidly. This fact seems to show that the rearrangement of cellulose molecules does not occur as a whole but only partly in the vicinity of the OH groups which affect the process of H → D exchange. If large amounts of water are supplied, however, cellulose molecules rearrange freely and provide a crystalline structure, as observed clearly by x‐ray. On the other hand, during the heat‐treatment of amorphous cellulose, the decrease of α andDodcan be clearly observed by DSC and IR from the initial stage of treatment. Judging from the change of α andDod, it was inferred that the hydrogen bond formation occurs step by step simultaneously with the rearrangement of cellulose molecules b

ISSN:0025-116X    

DOI:10.1002/macp.1981.021820606

出版商:Hüthig&Wepf Verlag    

年代:1981

数据来源: WILEY

摘要:

AbstractWith the intention to prove the possibility of applying the Diels‐Alder reaction to trap a trace amount of residual styrene monomer in polystyrene, a model reaction between cyclopentadiene with styrene in a diluteo‐chlorobenzene solution was carried out. In the presence of an excess amount of dicyclopentadiene, the consumption of styrene was measured with time lapse by means of gaschromatography. At temperatures ranging from 140 to 220°C, the amount of styrene was observed to decrease remarkably until it reached an equilibrium concentration. The higher the temperature was, the higher the equilibrium concentration became. The equilibrium constants at each temperature and the activation energy for the reaction were calcul

ISSN:0025-116X    

DOI:10.1002/macp.1981.021820607

出版商:Hüthig&Wepf Verlag    

年代:1981

数据来源: WILEY

摘要:

AbstractNew nitrogen mustard analogues in which bis(2‐chloroethyl)‐amino groups are separated by oxyethylene groups, 1,14‐dichloro‐3,12‐bis(2‐chloroethyl)‐3,12‐diaza‐6,9‐dioxatetradecan (3c) and 1,17‐dichloro‐3,15‐bis(2‐chloroethyl)‐3,15‐diaza‐6,9,12‐trioxaheptadecane (3d), were synthesized by reaction of bis(2‐hydroxyethyl)amine (2) with bis(2‐chloroethyoxy)ethylene (1a) and with 1,11‐dichloro‐3,6,9‐trioxaundecane (1b), respectively, followed by treatment with thionyl chloride. The analogues were then complexed with heparin. The resulting heparin‐complexes show inhibiting acti

ISSN:0025-116X    

DOI:10.1002/macp.1981.021820608

出版商:Hüthig&Wepf Verlag    

年代:1981

数据来源: WILEY

摘要:

AbstractThree cyclopentamers (2a–c) and a chainlike pentanuclear oligomer (3a) were prepared by stepwise syntheses. The molecules of the cyclic compounds with 20 links containo,o′‐methylene bridged 2‐hydroxy‐5‐methyl‐1,3‐phenylene or 2‐hydroxy‐5‐tert‐butyl‐1,3‐phenylene units in a strictly defined manner. The properties of the cyclic pentamer2aand the chainlike pentanuclear oligomer3awere compared. They differ by their solubilities, melting points, IR and1H NMR spectra (pseudorotation) and fragmentation behaviour shown by their mass spectra. The pseudorotation of the cyclic compounds

ISSN:0025-116X    

DOI:10.1002/macp.1981.021820609

出版商:Hüthig&Wepf Verlag    

年代:1981

数据来源: WILEY

摘要:

AbstractThe synthesis of triblock copolymers with crystalline outer blocks of polybutyramide and a central block of polystyrene or polyisoprene was performed. First polystyrene (or polyisoprene) fitted at both ends with acyllactam functions were obtained. In a second step these endstanding functions promote the lactame polymerization to yield the polyamide blocks. A careful characterization of the resulting samples was carried out. The behaviour of these block copolymers is typically that of a thermoplastic elastomer, whereby the crystalline blocks constitute the physical crosslinks in the samples.

ISSN:0025-116X    

DOI:10.1002/macp.1981.021820610

出版商:Hüthig&Wepf Verlag    

年代:1981

数据来源: WILEY