摘要:

AbstractThis review describes immunoaffinity purification as a tool for the processscale isolation of high‐value, therapeutic‐grade biochemicals from complex media. To this end, practicalities of activation, antigen coupling and operation in anti‐human IgG monoclonal antibody recovery have been studied using cyanogen‐bromide activated Sepharose CL‐4B and composite Macrosorb K4AX immobilised with polyclonal human IgG as a model for general immunoaffinity systems. The characteristics required of solid phases are discussed in the context of the efficient application of bioselective processes early in the purification sequences. The importance of the technique for isolating biologically active biomolecules for in‐vivo administration has been discussed in the light of current, stringent regulatory requirements. Finally, the prospect of scale‐up and automation of the technique has b

ISSN:0268-2575    

DOI:10.1002/jctb.280480202

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractThe spectrophotometric properties of zinc complexes with murexide in the absence and presence of cationic, anionic and nonionic surfactants were studied. The addition of cationic surfactants stabilized the complex and hence improved the intensity of the absorption band(sensitized the reaction).A method for the determination of>0.01% zinc in aluminum metal and some aluminum base alloys was developed. The method was based on measuring the absorbance of the formed complex with murexide and cetylpyridinium bromide at pH 8. The apparent molar absorptivity was 4.7 ± 0.01 × 104litre mol−1cm−1at 470 nm. A linear calibration curve was obtained for up to 1.44 ppm of zinc. In the presence of sodium fluoride and thiourea masking solutions, common ions in aluminum metal and alloys did not inte

ISSN:0268-2575    

DOI:10.1002/jctb.280480203

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractCondensation of mono‐ and di‐bromo‐derivatives of 1,5‐dihydroxy‐4,8‐diaminoanthraquinone and of 1,8‐dihydroxy‐4,5‐diaminoanthraquinone with phenols and thiols afforded the corresponding β‐ethers and thioethers. These compounds coloured polyester in bright reddish‐blue to greenish‐blue hues of generally good fastness to light and sublimation. The colour of the dyes is discussed with respect to the nature and orientat

ISSN:0268-2575    

DOI:10.1002/jctb.280480204

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractTetrahydrofurfuryl alcohol could be obtained by catalytic hydrogenation of either furfural or furfuryl alcohol using Pd‐, Ru‐, Rh‐ and Ni‐supported catalysts as well as their mixtures with a Cu‐supported catalyst. In the case of furfural hydrogenation, the best results (97 % yield, 100 % conversion, 98 % selectivity) were obtained in the presence of Ni and Cu. However, this catalytic mixture could not be recycled. In the case of furfuryl alcohol hydrogenation, Ni‐supported catalysts were the most active. Nickel‐onsilica‐alumina catalyst containing 59 % of metal lead to the best results (98–99 % yield, selectivity and conversion>99 %). Moreover, it could be recycled. Hydrogenation of furfuryl alcohol in the presence of this catalyst was the best procedure for the production of tetrahydr

ISSN:0268-2575    

DOI:10.1002/jctb.280480205

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractNonionic surfactants above their critical micelle concentration in aqueous solution phase separate, at the cloud point, as the temperature is raised as a result of concommitant changes in micellar size, shape and interactions. We discuss the ways in which the cloud point changes in the presence of various additives. If(sufficient)alkane is solubilised in aqueous surfactant (or water in an alkane solution) single phase microemulsions result. If further alkane(or water)is added separation into two phases occurs. Depending on temperature, the separation results from either attainment of the natural curvature of the surfactant film coating the microemulsion drops, or from interactions between droplets. In two phase(oil+aqueous)systems, one phase is a microemulsion and the other the excess of the dispersed(droplet)phase. The type of microemulsion obtained(i.e. the hydrophile‐lipophile balance of the system)depends on the temperature, and can be understood in terms of changes in the natural curvature of the surfactant films with temperatur

ISSN:0268-2575    

DOI:10.1002/jctb.280480206

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractA commercial mixture of methylcyclopentadiene dimers mainly consisting of four dimeric compounds with partial structures of 1‐methyl‐ and 2‐methylnorbornene, undergoes slow oxidation and isomerization when it is dissolved in CH2Cl2, CHCl3or CCl4. Both reactions are simultaneous but independent of each other. Isomerization only concerns those isomers that contain in their structure a 2‐methylnorbornene ring.The nature of the isomerization and the influence of different acid media is

ISSN:0268-2575    

DOI:10.1002/jctb.280480207

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractAlpha‐amylase fromAspergillus oryzaehas been immobilized onto corn grits and porous silica(specific areas 180 and 440 m2g−1).Kinetic parameters of immobilized enzyme have been determined.Immobilization of alpha‐amylase results in the formation of less polymerized products resulting in an apparent decrease in the number of transglycosylation reactions, for both maltotetraose and starch as substrates, when compared with free enzyme.Diffusional limitations for substrate and products have been quantified in the case of the three supports used. External diffusional resistances were important in all cases for the reaction products, whilst they became negligible for the substrate in the case of silica supports. Moreover, internal transfer limitations were identified with silica 180 m2g−1support. It was demonstrated that diffusional resistances were in direct relation to the apparent modification of the enzyme action pattern after immobil

ISSN:0268-2575    

DOI:10.1002/jctb.280480208

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractLipase from porcine pancreas was immobilized on cellulose beads having various degrees of hydrophobicity, by covalent linking and by hydrophobic adsorption. Lipolytic activity was measured in heterogeneous organicaqueous systems of various hydrophobicities using olive oil as a substrate. The main factors influencing lipase activity were hydrophobicity of the reaction mixture and of the carrier. Carriers with increased hydrophobicity enhanced lipase activity more than less hydrophobic ones. Lipase immobilized covalently on cellulose beads was less active than that adsorbed onto tritylcellulose but was considerably more thermostable.

ISSN:0268-2575    

DOI:10.1002/jctb.280480209

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractMeasured activation energies of ignition of a wide variety of solid materials of practical importance are tabulated. The Frank‐Kamenetskii model of thermal ignition was used in their determination. Comments are made on the values in terms of the nature of the respective materials and in terms of the value of the measured quantities as input to mathematical simulation of ignitio

ISSN:0268-2575    

DOI:10.1002/jctb.280480210

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractA new nitrile hydratase producing strain ofRhodococcushas been found. A method for purification of the nitrile hydratase and a characterization of the enzyme is described. The hydratase is a 52‐kdal protein consisting of two subunits of molecular weights, 26 and 23 kdal, respectively.The hydratase exhibits a broad substrate specificity. Aliphatic saturated or unsaturated nitriles, as well as aromatic nitriles, are substrates for the enzyme. Inhibition of the enzyme activity by amides and carboxylic acids was observed. The optimum pH of the hydratase is 7.5. The enzyme is rather unstable, even at room temperature.The enzyme may be applied for the production of acrylamide. For this application of the enzyme, the optimal temperature is about 4°C, where the enzyme exhibits a satisfactory activity and stabili

ISSN:0268-2575    

DOI:10.1002/jctb.280480211

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY