Enzyme engineering

Wingard, Lemuel B.

doi:10.1007/bfb0006665

Cited by 20 publications

(1 citation statement)

References 139 publications

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“…116 The plugflow columns have recently been used for milk and whey treatment. 31 • 46>5S>58>82 Milk and whey have very low viscosity and lactose, i.e., the substrate for the reactor is a very highly soluble constituent thereof.…”

Section: Reactors For Milk and Whey Treatmentmentioning

confidence: 99%

Beta‐galactosidase technology: A solution to the lactose problem

Shukla¹,

Wierzbicki

1975

C R C Critical Reviews in Food Technology

124

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Section: Reactors For Milk and Whey Treatmentmentioning

confidence: 99%

Beta‐galactosidase technology: A solution to the lactose problem

Shukla¹,

Wierzbicki

1975

C R C Critical Reviews in Food Technology

124

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Yeast alcohol dehydrogenase immobilized in a glutaraldehyde–albumin matrix: Kinetics and cofactor diffusional effects*

Millis¹,

Wingard²

1981

Biotech & Bioengineering

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SummaryThis study was carried out to define how the overall rate of reaction would be influenced by different degrees of diffusional resistance to cofactor transport within an oxidoreductase membrane matrix. To accomplish this, 0.7-6.6pM yeast alcohol dehydrogenase was immobilized in an albumin matrix crosslinked with 2.5 or 5.0% glutaraldehyde to give 102-1685 pm thick membranes. The enzyme half-life was at least doubled at pH 7.5 or 8.8 on immobilization. Values of the kinetic constants for the soluble and immobilized enzyme were determined at 25°C and pH 8.8 over the range of 0.01-1.0M bulk solution concentration of ethanol as substrate and 140-1000pM bulk solution concentration of nicotinamide adenine dinucleotide (NAD+) as cofactor, to give essentially single substrate kinetics in NAD+ .Equilibrium partitioning of ethanol and NAD' between the solution and membrane was measured and used in the data analysis. The four kinetic constants for the soluble enzyme agreed with literature values; and all increased with immobilization of the enzyme. The Michaelis constants for NAD+ and for ethanol were greater for the immobilized enzyme. The diffusional resistance to NADi transport, presented in terms of the Thiele modulus, showed that the overall rate of reaction was decreased by about 50% even at values of the modulus as low as 2.0.

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Hollow‐fiber membrane bioreactors using immobilized E. coli for protein synthesis

Inloes

Smith

Taylor

et al. 1983

Biotech & Bioengineering

105

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Actively growing Escherichia coli C600(pBR322), immobilized within the macroporous matrix of asymmetric-wall hollow-fiber membranes, has been propagated to extremely high densities, typically more than 10(12) cells/mL of accessible void volume, in some regions cells accounting for nearly 100% of the available macrovoid volume forming a tissue-like mass. Production rates of beta-lactamase, an enzyme used as an indicator of the culture's biosynthetic potential, remained at high and relatively stable levels for more than three weeks of continuous operation, and effluent supernatant enzyme activities attained 25% of the accumulated level measured in a 24-h shaker-flask culture. Based on the accessible void volume within the fiber wall, the beta-lactamase productivity was independent of the specific asymmetric membrane used. On a per cell basis, however, cells cultured using hollow-fiber membranes were only 10% as productive as those in the shaker-flask culture, possibly due to the high packing density or culture aging. By contrast, the hollow-fiber bioreactor was 100 times more productive than the shaker-flask culture on a reactor-volume basis, primarily as a consequence of the high cell densities. Reactor productivity was dependent on the number of cells in the reactor, suggesting that reactor performance was kinetically controlled and not mass transport limited.

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Enzyme engineering

Cited by 20 publications

References 139 publications

Beta‐galactosidase technology: A solution to the lactose problem

Beta‐galactosidase technology: A solution to the lactose problem

Yeast alcohol dehydrogenase immobilized in a glutaraldehyde–albumin matrix: Kinetics and cofactor diffusional effects*

Hollow‐fiber membrane bioreactors using immobilized E. coli for protein synthesis

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