摘要:

AbstractPancreatic lipase has been immobilized onto stainless steel beads by adsorption followed by crosslinking, and onto polyacrylamide by covalent bonding. The activities of the two types of immobilized enzyme toward the particulate substrate, tributyrin emulsion droplets, were determined experimentally, and rate constants based on Michaelis‐Menten kinetics were calculated. The activity of the stainless steel–lipase was determined for various flow conditions and for various support sizes by the use of a differential fluidized bed recycle reactor. The rate constants calculated indicate that the experimental reaction rate is free from mass transfer influences, since the observed Michaelis constant does not vary with the fluidization velocity or with the support particle size. In addition, the Michaelis constant of the stainless steel–lipase was found to be equal to that of the free enzyme, suggesting that adsorption and subsequent crosslinking does not alter the enzyme–substrate affinity. The emulsion substrate mass transfer rates, calculated from the filtration theory, indicate that each substrate particle which contacts the immobilized enzyme is hydrolyzed to a significant extent. Theexperimentally determined kinetic rate constants may be used directly to predict the size of integral fluidized bed r

ISSN:0006-3592    

DOI:10.1002/bit.260171002

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

年代:1975

数据来源: WILEY

摘要:

AbstractEnzymatic hydrolysis of insoluble amorphous cellulose byTrichoderma viridecellulase was investigated in a batch reactor at several substrate concentrations and three enzyme levels. The reactions were carried out at 50°C and pH 4.8. Enzyme was rapidly adsorbed onto solids on contact, then gradually returned to the liquid phase as the reaction proceeded. A kinetic model that considered the fast adsorption which was followed by the slow reaction, and subsequent product inhibition was developed to interpret the experimental observations. The resulting equation successfully correlated the data for up to 70% conversion. The methods for determining the kinetic parameters are discussed

ISSN:0006-3592    

DOI:10.1002/bit.260171003

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

年代:1975

数据来源: WILEY

摘要:

AbstractUrate oxidase from hog liver (urate: oxygen oxidoreductase, EC 1.7.33) has been entrapped in a crosslinked 2‐hydroxyethyl methacrylate gel with a 47% retention of activity. The kinetic behavior of the gel entrapped enzyme has been studied in a slurried tank reactor using uric acid as substrate. Internal diffusion effects were found to be negligible for particle sizes below 128 μm. A threefold increase inKm(app) was observed for the 128 μm particles and attributed to diffusional effects. The pH activity profile of the gel entrapped enzyme was bell‐shaped at high substrate concentration and could be fitted to a titration curve of two ionizable groups, a basic group having a pKof 7.9 and an acidic group with a pKof 11.0. The gel entrapped enzyme showed excellent stability between pH 6.5 and

ISSN:0006-3592    

DOI:10.1002/bit.260171004

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

年代:1975

数据来源: WILEY

摘要:

AbstractA process for the utilization of modified whey syrups in wine alcohol fermentations is described. Palatable wines containing 10–12.5% alcohol were produced when various strains ofS. cerevisiaevar.ellipsoideuswere fermented with hydrolyzed whey permeate syrups and grape juice concentrates. Experimental control of final alcohol and residual sugar levels in the wines by various chaptalization techniques is discussed. The possibility of utilizing this process in areas where both whey and grapes are abundant is mentione

ISSN:0006-3592    

DOI:10.1002/bit.260171005

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

年代:1975

数据来源: WILEY

摘要:

AbstractThe kinetic properties of α‐galactosidase ofMortierella vinaceawere investigated in detail using PNPG (p‐nitrophenyl‐α‐D‐galactopyranoside) as a substrate. Consequently, the enzyme was markedly inhibited not only by the substrate, but also by the galactose hydrolized. The initial rate of reaction at sufficiently high substrate concentrations, however, did not fall to zero and did approach a finite value. Galactose behaved as a mixed inhibitor and was neither totally competitive nor totally noncompetitive. A rate equation was obtained from a generalized equation derived from a kinetic model which took both the inhibitions into consideration. The constants used in the equation were appropriately estimated. The calculated rate agreed fairly well with the observed initial rate. Moreover, the PNPG hydrolysis progressing in a batch system was found to be approximately representable by simple first order kinetics in which the rate constant was dependent on the initial substrate co

ISSN:0006-3592    

DOI:10.1002/bit.260171006

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

年代:1975

数据来源: WILEY

摘要:

AbstractA new suspension culture system (Mini‐AR) based on the Stoke's drag law for suspended particles is described. This apparatus can be utilized for the maintenance of mammalian kidney cells in both short‐ and long‐term cul

ISSN:0006-3592    

DOI:10.1002/bit.260171007

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

年代:1975

数据来源: WILEY

摘要:

AbstractTreatment ofGluconobacter melanogenusIFO 3293 cells with benzene, carbon tetrachloride, cyclohexane, deoxycholate, toluene, or xylene stimulated their conversion ofL‐sorbose toL‐sorbosone two‐ to threefold. The degree of stimulation depended upon the length of exposure time to the agent and the age of theG. melanogenuscells. A rapid decrease in viability of the cells and degradation of cell RNA was noted after treatment with the effective agents. TheG. melanogenuscells were unable to absorbL‐sorbose actively after toluene tr

ISSN:0006-3592    

DOI:10.1002/bit.260171008

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

年代:1975

数据来源: WILEY

摘要:

AbstractL‐Sorbose is oxidized to 2‐keto‐L‐gulonic acid (KGA) via the following sequence of reactions which we call the “sorbosone pathway”:L‐sorbose ⇌L‐sorbosone → KGA. The first step is reversible and is mediated by enzymes found in a soluble fraction obtained fromPseudomonas putidaATCC 21812. Although no cofactor requirements were found for the forward reaction, the reverse reaction clearly required NADH. Enzymes for this NADH‐dependent synthesis ofL‐sorbose could be differentiated on the basis of molecular weights. The second step in the sorbosone pathway is catalyzed by a particulate enzyme found in extracts fromP. putidaandGluconobacter melanogenusIFO 3293. The rate limiting reaction in the sorbosone pathway is the synthesis ofL‐sorbosone. In addition toP. putida,Klebsiella pneumoniae(ATCC 27858) andSerratia marcescens(ATCC 27857) also contain the enzymes which catalyze the reactions of the sorbosone pathway. Two of the bacteria studied,P. putidaandG. melanogenus, also contain an enzyme involved in the further metabolism of KGA toL‐idonic acid. This enzyme, referred to as KGA‐reductase, is found in the soluble fraction of cell‐free extracts an

ISSN:0006-3592    

DOI:10.1002/bit.260171009

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

年代:1975

数据来源: WILEY

摘要:

AbstractTo describe axial dispersion, particle film mass transfer, intraparticle diffusion, and the chemical reaction of the substrate for enzymes immobilized in porous particles in packed columns, we have developed mathematical models for first‐ and zero‐order limits of Michaelis‐Menten kinetics. Steady‐state solutions were derived for both long and short column boundary conditions and for plug flow. Theory was compared to experiments of hydrolysis of sucrose catalyzed by invertase bound to porous glass particles. Steady‐state conversions were measured for a range of flow rates. Pulse response experiments with inert packing were used to determine values of bed void fraction and particle

ISSN:0006-3592    

DOI:10.1002/bit.260171010

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

年代:1975

数据来源: WILEY

摘要:

AbstractWorking conditions of a biochemical fuel cell formed by an oxygen cathode and a platinum bioanode in aSaccharomyces cerevisiaesuspension metabolizing glucose are described. The biocell response in terms of bioanode potential and current drainage under different fermentation conditions is reported. A kinetic equation relating the current, the number of microorganisms, and the substrate concentration is obtained. The bioanode potential corresponds to that of an oxygen concentration polarization cell.

ISSN:0006-3592    

DOI:10.1002/bit.260171011

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

年代:1975

数据来源: WILEY