摘要:

AbstractThe enzyme β‐galactosidase (lactose) obtained from several microbial sources was immobilized on zirconia‐coated porous glass particles. The immobilized enzymes were characterized by determining pH profiles, kinetic constants, thermal profiles, and operationalhalf‐lives in lactose and whey ultrafiltrate solutions. Studies were carried out on continuous reactor performance, and enzyme requirements for scale‐up were estimated. Lactose or whey hydrolyzed by this technique could find use commercially as a sweetener in a number of dairy

ISSN:0006-3592    

DOI:10.1002/bit.260160302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractThe kinetic behavior of water insoluble enzyme columns was studied using the hydrolysis of GPNA (N‐glutaryl‐L‐phenylalanine‐p‐nitroanilide) by α‐chymotrypsin as a model. Thermal denaturation of soluble and insoluble enzyme was compared in a batch reactor and in a tubular reactor. Convection of metabolites, enzyme reaction, diffusion of metabolites across porous particles and the kinetic behavior of a water insoluble enzyme column were tested.The respective and mutual effects of the first two phenomena were comprehensively analyzed for both stationary state and transient conditions. When the ingoing substrate concentration was varying with time, convection‐reaction equations were solved by digital computation. The possible effects of diffusion limitations and unstirred layers

ISSN:0006-3592    

DOI:10.1002/bit.260160303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractOne of the main reasons for immobilizing an enzyme is to enable its reuse, or continuous use, in a reactor. Consequently immobilized enzyme stability is an important factor in enzyme reactor design. The performance of the reactor will decrease if during operation the support material disintegrates into smaller particles that pass out of the reactor system.When β‐galactosidase is immobilized by covalent attachment to AE‐cellulose, the smaller particles have a higher activity. After subjection of the immobilized enxyme to a shear stress the average particle size decreases and the total enzymic activity increases. A loss of small particles from the reactor, although constituting a small weight percent loss of support, will result in a disproportionately large loss in activity. The relevance of these observations to reactor performance is discu

ISSN:0006-3592    

DOI:10.1002/bit.260160304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractA tubular membrane reactor offers many advantages over a solid wall reactor to carry out an enzyme catalyzed reaction. With proper membrane selectivity, the product, may be separated from the reacting stream and the enzyme recycled for continuous reuse. In most cases, enzyme reuse contributes to the economic feasibility of a continuous enzyme catalyzed process. Furthermore, the efficiency and performance of a membrane reactor is greater than that of a solid wall reactor.Continuous hydrolysis of starch by the enzyme β‐amylase, carried out in a commercially available tubular membrane unit, is studied at different starch and enzyme concentrations for a given system pressure and inlet flow rate. Results show that the performance of the membrane reactor is in all cases greater than that of the solid wall reactor. A steady state in performance of permeation rate is, however, not reached by the membrane reactor, which shows a continuous decline within the periods examined in this study. This decline is caused in part by the aging of the starch solution, but mostly by the formation of a concentrated, or gel, layer at the membrane surface. This appears to be the main limiting factor for this process since the decline in reaction and permeation rate results in a severe decrease in the amount of maltose in the permea

ISSN:0006-3592    

DOI:10.1002/bit.260160305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractHen's egg white lysozyme (EC 3.2.1.17) has been covalently attached to a polystyrene matrixviainteraction of protein nucleophiles with an aromatic imidazolide function under anhydrous conditions. The polymer‐enzyme complex is prepared in a way which allows nonaqueous solubilization of the complex. The activity of the bound enzyme compares favorably with the activity of the native protein. The pH optima for the matrix‐supported protein are shifted toward the basic side. The effect of substrate concentration on rate has been determined. (A preliminary report of this work has been published: G. J. Bartling, H. D. Brown, S. K. Chattopadhyay,Nature243, 342–344 (1

ISSN:0006-3592    

DOI:10.1002/bit.260160306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractThe disintegration of baker's yeast (Saccharomyces cerevisiae) by a high pressure homogenizer, to a pressure of 25,000 psi. (172.37 MNm−2) is described, together with details of the methods of measurement used to obtain information on the valve movement and pressure transients. The theory of the mechanism of cell disintegration is discusse

ISSN:0006-3592    

DOI:10.1002/bit.260160307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractTrypsin (EC 3.4.4.4) was immobilized in low yield on aminoalkylsilylated magnetite (Fe3O4). Better results were obtained when trypsin was immobilized by crosslinking with glutaraldehyde on magnetite. The preparation contained 36 mg protein/g magnetite and the enzyme retained 46% and 11% of esterase and proteolytic activity. Immobilized trypsin was more heat stable than trypsin. Invertase (β‐D‐fructofuranoside fructohydrolase, EC 3.2.1.26) was cross‐linked on magnetite with glutaraldehyde in low yield due to the inactivation of the enzyme. However in the presence of 1% sucrose, the total activity recovered was 79% of the initial activity and the preparation contained 4.4 mg/g of active invertase. Immobilized invertase was less active than invertase when acting on oligosaccharides of the raffinose family. The immobilized enzymes could be easily recovered, from solutions or suspensions, magnet

ISSN:0006-3592    

DOI:10.1002/bit.260160308

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractPartially purified lactoses (β‐D‐galactoside galactohydrolase, EC 3.2.1.23) fromAspergillus niger,Ladobacillus helveticus, andSaccharomyces lactiswere immobilized on diazotized porous glass particles (mean pore diameter, 86.5 nm: particle size diameters, 75–125 μm). In acid whey containing 4–4.5% lactose,A. nigerlactase gave the highest activity (89 μmoles lactose hydrolyzed/g glass, min) at 55°C and pH 4.5. Glass‐immobilizedA. nigerlaclases (lactase‐BG) retained much hydrolytic activity after storage and periodic use for 165 days at 55°C. For values ofXgreater than 30%, hydrolysis of 0.12Mlactose in acid whey by a continuous flow column packed with 2 ml of lactase‐BG particles could be correlated byX= 17.2(V/F) + 12.5 whereX= lactose hydrolysis, percent of lactose originally present;V= volume of packed bed of lactase‐BG, ml;F= flow rate

ISSN:0006-3592    

DOI:10.1002/bit.260160309

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

ISSN:0006-3592    

DOI:10.1002/bit.260160310

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

ISSN:0006-3592    

DOI:10.1002/bit.260160311

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY