-
3
-
-
0032479388
-
Lipases: Interfacial enzymes with attractive applications
-
Schmid R.D., Verger R. Lipases: interfacial enzymes with attractive applications. Angew Chem Int Ed. 37:1998;1609-1633.
-
(1998)
Angew Chem Int Ed
, vol.37
, pp. 1609-1633
-
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Schmid, R.D.1
Verger, R.2
-
4
-
-
0032167489
-
Microbial lipases form versatile tools for biotechnology
-
Jaeger K.E., Reetz M.T. Microbial lipases form versatile tools for biotechnology. Trends Biotechnol. 16:1998;396-403.
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(1998)
Trends Biotechnol
, vol.16
, pp. 396-403
-
-
Jaeger, K.E.1
Reetz, M.T.2
-
7
-
-
0032993482
-
Effects of metal salts on the structure and activity of alpha-chymotrypsin in ethanol water
-
Sasaki T., Kise H. Effects of metal salts on the structure and activity of alpha-chymotrypsin in ethanol water. Bull Chem Soc Jpn. 72:1999;1321-1325.
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(1999)
Bull Chem Soc Jpn
, vol.72
, pp. 1321-1325
-
-
Sasaki, T.1
Kise, H.2
-
8
-
-
0033591415
-
Drastic enhancement of the enantioselectivity of lipase-catalysed esterification in organic solvents by the addition of metal ions
-
Aqueous salt solutions were added to isopropyl-ether-based reaction mixtures for esterification of phenoxypropionic acids. Whereas water alone increased rates with both enantiomers, LiCl inhibited reaction of the wrong enantiomer. Enantioselectivity at the optimum final LiCl concentration of around 12 mM was five-times better than with water alone.
-
Okamoto T., Ueji S. Drastic enhancement of the enantioselectivity of lipase-catalysed esterification in organic solvents by the addition of metal ions. Chem Commun. 1999;939-940. Aqueous salt solutions were added to isopropyl-ether-based reaction mixtures for esterification of phenoxypropionic acids. Whereas water alone increased rates with both enantiomers, LiCl inhibited reaction of the wrong enantiomer. Enantioselectivity at the optimum final LiCl concentration of around 12 mM was five-times better than with water alone.
-
(1999)
Chem Commun
, pp. 939-940
-
-
Okamoto, T.1
Ueji, S.2
-
9
-
-
0033586348
-
Protein refolding in predominantly organic media markedly enhanced by common salts
-
Aqueous lysozyme solutions denatured by 8 M urea were diluted into aqueous-organic mixtures (usually 60% solutions of various diols). Some refolding to catalytically active lysozyme occurs, and the yield is greater in the presence of certain salts. For example, 1 M LiCl in 80% ethylene glycol raises the yield from 3% to 22%. The mechanism is thought to involve salting-in of forms that would otherwise aggregate irreversibly.
-
Rariy R.V., Klibanov A.M. Protein refolding in predominantly organic media markedly enhanced by common salts. Biotechnol Bioeng. 62:1999;704-710. Aqueous lysozyme solutions denatured by 8 M urea were diluted into aqueous-organic mixtures (usually 60% solutions of various diols). Some refolding to catalytically active lysozyme occurs, and the yield is greater in the presence of certain salts. For example, 1 M LiCl in 80% ethylene glycol raises the yield from 3% to 22%. The mechanism is thought to involve salting-in of forms that would otherwise aggregate irreversibly.
-
(1999)
Biotechnol Bioeng
, vol.62
, pp. 704-710
-
-
Rariy, R.V.1
Klibanov, A.M.2
-
10
-
-
0033586738
-
Optimizing the salt induced activation of enzymes in organic solvents: Effects of lyophilization time and water content
-
Subtilisin and a lipase were lyophilized to give powders of around 99% salts. As lyophilization time increased from 50 hours to 90 hours, the water content of the resulting powders progressively decreased. Catalytic activity also changed by up to 10-fold, increasing at first, then decreasing.
-
Ru M.T., Dordick J.S., Reimer J.A., Clark D.S. Optimizing the salt induced activation of enzymes in organic solvents: effects of lyophilization time and water content. Biotechnol Bioeng. 63:1999;233-241. Subtilisin and a lipase were lyophilized to give powders of around 99% salts. As lyophilization time increased from 50 hours to 90 hours, the water content of the resulting powders progressively decreased. Catalytic activity also changed by up to 10-fold, increasing at first, then decreasing.
-
(1999)
Biotechnol Bioeng
, vol.63
, pp. 233-241
-
-
Ru, M.T.1
Dordick, J.S.2
Reimer, J.A.3
Clark, D.S.4
-
11
-
-
0033553149
-
Markedly enhancing enzymatic enantioselectivity in organic solvents by forming substrate salts
-
Addition of bulky organic acids significantly improves lipase enantioselectivity with the amine PheOMe as substrate. Bulky amines have similar effects with acid substrates in reactions with subtilisin and a lipase. The effects are attributed to formation of ion-paired salts in the organic medium. Structure-based calculations indicate the counter-ion interferes more with the binding of the less-favoured enantiomer.
-
Ke T., Klibanov A.M. Markedly enhancing enzymatic enantioselectivity in organic solvents by forming substrate salts. J Am Chem Soc. 121:1999;3334-3340. Addition of bulky organic acids significantly improves lipase enantioselectivity with the amine PheOMe as substrate. Bulky amines have similar effects with acid substrates in reactions with subtilisin and a lipase. The effects are attributed to formation of ion-paired salts in the organic medium. Structure-based calculations indicate the counter-ion interferes more with the binding of the less-favoured enantiomer.
-
(1999)
J Am Chem Soc
, vol.121
, pp. 3334-3340
-
-
Ke, T.1
Klibanov, A.M.2
-
12
-
-
0033553105
-
Rationalization of the enantio-selectivity of subtilisin in DMF
-
Colombo G., Toba S., Merz K.M. Rationalization of the enantio-selectivity of subtilisin in DMF. J Am Chem Soc. 121:1999;3486-3493.
-
(1999)
J Am Chem Soc
, vol.121
, pp. 3486-3493
-
-
Colombo, G.1
Toba, S.2
Merz, K.M.3
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13
-
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0032407760
-
X-ray studies on two forms of bovine beta-trypsin crystals in neat cyclohexane
-
Zhu G.Y., Huang Q.C., Wang Z.M., Qian M.X., Jia Y.S., Tang Y.Q. X-ray studies on two forms of bovine beta-trypsin crystals in neat cyclohexane. Biochim Biophys Acta. 1429:1998;142-150.
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(1998)
Biochim Biophys Acta
, vol.1429
, pp. 142-150
-
-
Zhu, G.Y.1
Huang, Q.C.2
Wang, Z.M.3
Qian, M.X.4
Jia, Y.S.5
Tang, Y.Q.6
-
14
-
-
0033573935
-
Volatile buffers can override the 'pH memory' of subtilisin catalysis in organic media
-
'pH memory' disappears if a volatile buffer such as ammonium formate is used. Drying from buffers containing just one of these ions will cause large changes in protonation state. The role of counter-ions in controlling acid-base status is stressed.
-
Zacharis E., Halling P.J., Rees D.G. Volatile buffers can override the 'pH memory' of subtilisin catalysis in organic media. Proc Natl Acad Sci USA. 96:1999;1201-1205. 'pH memory' disappears if a volatile buffer such as ammonium formate is used. Drying from buffers containing just one of these ions will cause large changes in protonation state. The role of counter-ions in controlling acid-base status is stressed.
-
(1999)
Proc Natl Acad Sci USA
, vol.96
, pp. 1201-1205
-
-
Zacharis, E.1
Halling, P.J.2
Rees, D.G.3
-
15
-
-
0033545522
-
The effect of counterion, water concentration, and stirring on the stability of subtilisin BPN' in organic solvents
-
Sears P., Witte K., Wong C.H. The effect of counterion, water concentration, and stirring on the stability of subtilisin BPN' in organic solvents. J Mol Catal B. 6:1999;297-304.
-
(1999)
J Mol Catal B
, vol.6
, pp. 297-304
-
-
Sears, P.1
Witte, K.2
Wong, C.H.3
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16
-
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0032497415
-
Kinetic study of chemoselective acylation of amino-alditol by immobilized lipase in organic solvent: Effect of substrate ionization
-
When oleic acid is in excess over the co-substrate N-methylglucamine, ester synthesis becomes progressively more favoured relative to amide formation. This is attributed to protonation of the substrate amino group, making it unavailable for reaction. With an excess of base in the medium, either glucamine or a non-reactive tertiary amine, amide synthesis is favoured.
-
Maugard T., Remaud-Simeon M., Monsan P. Kinetic study of chemoselective acylation of amino-alditol by immobilized lipase in organic solvent: effect of substrate ionization. Biochim Biophys Acta. 1387:1998;177-183. When oleic acid is in excess over the co-substrate N-methylglucamine, ester synthesis becomes progressively more favoured relative to amide formation. This is attributed to protonation of the substrate amino group, making it unavailable for reaction. With an excess of base in the medium, either glucamine or a non-reactive tertiary amine, amide synthesis is favoured.
-
(1998)
Biochim Biophys Acta
, vol.1387
, pp. 177-183
-
-
Maugard, T.1
Remaud-Simeon, M.2
Monsan, P.3
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17
-
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0002662732
-
Enhancement of Candida antarctica lipase B enantioselectivity and activity in organic solvents
-
Parker M.C., Brown S.A., Robertson L., Turner N.J. Enhancement of Candida antarctica lipase B enantioselectivity and activity in organic solvents. Chem Commun. 1998;2247-2248.
-
(1998)
Chem Commun
, pp. 2247-2248
-
-
Parker, M.C.1
Brown, S.A.2
Robertson, L.3
Turner, N.J.4
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18
-
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0002975120
-
Effect of salt hydrate pair on lipase-catalyzed regioselective monoacylation of sucrose
-
Kim J.E., Han J.J., Yoon J.H., Rhee J.S. Effect of salt hydrate pair on lipase-catalyzed regioselective monoacylation of sucrose. Biotechnol Bioeng. 57:1998;121-125.
-
(1998)
Biotechnol Bioeng
, vol.57
, pp. 121-125
-
-
Kim, J.E.1
Han, J.J.2
Yoon, J.H.3
Rhee, J.S.4
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19
-
-
0032917548
-
Enhancement of immobilized protease catalyzed dipeptide synthesis by the presence of insoluble protonated nucleophile
-
2 hydrochloride was used as amino-component for a chymotrypsin reaction, rates were maximal for less-than-stoichiometric additions of triethylamine. The un-neutralised hydrochloride promotes separation of a water-rich liquid phase around the catalyst particles.
-
2 hydrochloride was used as amino-component for a chymotrypsin reaction, rates were maximal for less-than-stoichiometric additions of triethylamine. The un-neutralised hydrochloride promotes separation of a water-rich liquid phase around the catalyst particles.
-
(1999)
Enzyme Microb Technol
, vol.24
, pp. 480-488
-
-
Barros, R.J.1
Wehtje, E.2
Adlercreutz, P.3
-
20
-
-
0029959897
-
Prediction of the solvent dependence of enzymatic prochiral selectivity by means of structure-based thermodynamic calculations
-
Ke T., Wescott C.R., Klibanov A.M. Prediction of the solvent dependence of enzymatic prochiral selectivity by means of structure-based thermodynamic calculations. J Am Chem Soc. 118:1996;3366-3374.
-
(1996)
J Am Chem Soc
, vol.118
, pp. 3366-3374
-
-
Ke, T.1
Wescott, C.R.2
Klibanov, A.M.3
-
21
-
-
0029818293
-
Rational control of enzymatic enantioselectivity through solvation thermodynamics
-
Wescott C.R., Noritomi H., Klibanov A.M. Rational control of enzymatic enantioselectivity through solvation thermodynamics. J Am Chem Soc. 118:1996;10365-10370.
-
(1996)
J Am Chem Soc
, vol.118
, pp. 10365-10370
-
-
Wescott, C.R.1
Noritomi, H.2
Klibanov, A.M.3
-
22
-
-
0032513720
-
Insights into the solvent dependence of chymotryptic prochiral selectivity
-
The previously reported [20] solvent effect on selectivity in acetylation of 2-(3,5-dimethoxybenzyl)-1,3-propanediol is shown to be largely attributable to effects on kinetics of the pro-R reaction. This is rationalised by modelling of the transition state structures.
-
Ke T., Klibanov A.M. Insights into the solvent dependence of chymotryptic prochiral selectivity. J Am Chem Soc. 120:1998;4259-4263. The previously reported [20] solvent effect on selectivity in acetylation of 2-(3,5-dimethoxybenzyl)-1,3-propanediol is shown to be largely attributable to effects on kinetics of the pro-R reaction. This is rationalised by modelling of the transition state structures.
-
(1998)
J Am Chem Soc
, vol.120
, pp. 4259-4263
-
-
Ke, T.1
Klibanov, A.M.2
-
23
-
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0031770229
-
On the role of transition-state substrate desolvation in enzymatic enantioselectivity in aqueous-organic mixtures
-
Literature data on the effects of co-solvent addition on enantioselectivity were analysed using the authors' own method consisting of the desolvation of different parts of the isomeric transition states. In this case calculated energetics of desolvation did not explain the observed effects.
-
Luque S., Ke T., Klibanov A.M. On the role of transition-state substrate desolvation in enzymatic enantioselectivity in aqueous-organic mixtures. Biocatal Biotrans. 16:1998;233-248. Literature data on the effects of co-solvent addition on enantioselectivity were analysed using the authors' own method consisting of the desolvation of different parts of the isomeric transition states. In this case calculated energetics of desolvation did not explain the observed effects.
-
(1998)
Biocatal Biotrans
, vol.16
, pp. 233-248
-
-
Luque, S.1
Ke, T.2
Klibanov, A.M.3
-
24
-
-
0032499234
-
Application of structure-based thermodynamic calculations to the rationalization of the enantioselectivity of subtilisin in organic solvents
-
Enantioselectivity in the subtilisin-catalysed transesterification of 1-phenylethanol and trans-sobrerol varied up to sixfold between different solvents. The method of Wescott et al. [21] was applied to rationalise the results in this resolution, but gave only a weak correlation.
-
Colombo G., Ottolina G., Carrea G., Bernardi A., Scolastico C. Application of structure-based thermodynamic calculations to the rationalization of the enantioselectivity of subtilisin in organic solvents. Tetrahedron-Asymmetry. 9:1998;1205-1214. Enantioselectivity in the subtilisin-catalysed transesterification of 1-phenylethanol and trans-sobrerol varied up to sixfold between different solvents. The method of Wescott et al. [21] was applied to rationalise the results in this resolution, but gave only a weak correlation.
-
(1998)
Tetrahedron-Asymmetry
, vol.9
, pp. 1205-1214
-
-
Colombo, G.1
Ottolina, G.2
Carrea, G.3
Bernardi, A.4
Scolastico, C.5
-
25
-
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0032552502
-
Lipase-catalyzed transesterification in organic media: Solvent effects on equilibrium and individual rate constants
-
Garcia-Alles L.F., Gotor V. Lipase-catalyzed transesterification in organic media: solvent effects on equilibrium and individual rate constants. Biotechnol Bioeng. 59:1998;684-694.
-
(1998)
Biotechnol Bioeng
, vol.59
, pp. 684-694
-
-
Garcia-Alles, L.F.1
Gotor, V.2
-
26
-
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0032946805
-
Kinetics of lipase-catalysed esterification in organic media: Correct model and solvent effects on parameters
-
Janssen A.E.M., Sjursnes B.J., Vakurov A.V., Halling P.J. Kinetics of lipase-catalysed esterification in organic media: correct model and solvent effects on parameters. Enzyme Microb Technol. 24:1999;463-470.
-
(1999)
Enzyme Microb Technol
, vol.24
, pp. 463-470
-
-
Janssen, A.E.M.1
Sjursnes, B.J.2
Vakurov, A.V.3
Halling, P.J.4
-
27
-
-
0032032060
-
Lipase-catalyzed enantioselective esterification of ibuprofen in organic solvents under controlled water activity
-
Ducret A., Trani M., Lortie R. Lipase-catalyzed enantioselective esterification of ibuprofen in organic solvents under controlled water activity. Enzyme Microb Technol. 22:1998;212-216.
-
(1998)
Enzyme Microb Technol
, vol.22
, pp. 212-216
-
-
Ducret, A.1
Trani, M.2
Lortie, R.3
-
28
-
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0043213963
-
Thermodynamic and kinetic aspects on water vs. organic solvent as reaction media in the enzyme-catalysed reduction of ketones
-
Rates and enantioselectivities were measured between -1°C and 50°C in hexane. The rate increased 16-fold between water activity 0.53 and 0.97 - a significant increase in activation enthalpy was more than compensated by a fall in entropy, -TΔS.
-
Jönsson A., Wehtje E., Adlercreutz P., Mattiasson B. Thermodynamic and kinetic aspects on water vs. organic solvent as reaction media in the enzyme-catalysed reduction of ketones. Biochim Biophys Acta. 1430:1999;313-322. Rates and enantioselectivities were measured between -1°C and 50°C in hexane. The rate increased 16-fold between water activity 0.53 and 0.97 - a significant increase in activation enthalpy was more than compensated by a fall in entropy, -TΔS.
-
(1999)
Biochim Biophys Acta
, vol.1430
, pp. 313-322
-
-
Jönsson, A.1
Wehtje, E.2
Adlercreutz, P.3
Mattiasson, B.4
-
29
-
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0032894468
-
The temperature dependence of enzymatic kinetic resolutions reveals the relative contribution of enthalpy and entropy to enzymatic enantioselectivity
-
Enantioselectivity was measured for lipase-catalysed hydrolysis in water and esterification in hexane, with a variety of enzymes and substrates. Differences in activation entropy make a major contribution to discrimination in most cases. Literature data on various enzymic resolutions suggests enthalpy-entropy compensation, but this partly reflects the range of enantioselectivities that can be measured experimentally.
-
Overbeeke P.L.A., Ottosson J., Hult K., Jongejan J.A., Duine J.A. The temperature dependence of enzymatic kinetic resolutions reveals the relative contribution of enthalpy and entropy to enzymatic enantioselectivity. Biocatal Biotrans. 17:1999;61-79. Enantioselectivity was measured for lipase-catalysed hydrolysis in water and esterification in hexane, with a variety of enzymes and substrates. Differences in activation entropy make a major contribution to discrimination in most cases. Literature data on various enzymic resolutions suggests enthalpy-entropy compensation, but this partly reflects the range of enantioselectivities that can be measured experimentally.
-
(1999)
Biocatal Biotrans
, vol.17
, pp. 61-79
-
-
Overbeeke, P.L.A.1
Ottosson, J.2
Hult, K.3
Jongejan, J.A.4
Duine, J.A.5
-
31
-
-
0032478326
-
Effect of pressure on the catalytic activity of subtilisin Carlsberg suspended in compressed gases
-
Effects at fixed water activity were modest in compressed propane and t-amyl alcohol, but increasing pressures up to 300 bar reduced rates substantially in near-critical ethane and carbon dioxide, corresponding to large positive activation volumes.
-
Fontes N., Nogueiro E., Elvas A.M., de Sampaio T.C., Barreiros S. Effect of pressure on the catalytic activity of subtilisin Carlsberg suspended in compressed gases. Biochim Biophys Acta. 1383:1998;165-174. Effects at fixed water activity were modest in compressed propane and t-amyl alcohol, but increasing pressures up to 300 bar reduced rates substantially in near-critical ethane and carbon dioxide, corresponding to large positive activation volumes.
-
(1998)
Biochim Biophys Acta
, vol.1383
, pp. 165-174
-
-
Fontes, N.1
Nogueiro, E.2
Elvas, A.M.3
De Sampaio, T.C.4
Barreiros, S.5
-
32
-
-
0032573075
-
Comparison of X-ray crystal structures of an acyl-enzyme intermediate of subtilisin Carlsberg formed in anhydrous acetonitrile and in water
-
The structure of the trans-cinnamoyl intermediate formed in acetonitrile-soaked crystals is essentially the same as that formed in water. An acetonitrile molecule found in the substrate binding site of the free enzyme is displaced in the acyl-enzyme, while a second acetonitrile continues to occupy the site of the nucleophilic water in the aqueous structure. Crystals soaked in acetonitrile for long periods, or those that are air dried, have low active site contents (by phenylmethanesulfonyl fluoride [PMSF] titration) and become impermeable to a tracer dye. The authors emphasize the importance of the supramolecular structure of the crystals.
-
Schmitke J.L., Stern L.J., Klibanov A.M. Comparison of X-ray crystal structures of an acyl-enzyme intermediate of subtilisin Carlsberg formed in anhydrous acetonitrile and in water. Proc Natl Acad Sci USA. 95:1998;12918-12923. The structure of the trans-cinnamoyl intermediate formed in acetonitrile-soaked crystals is essentially the same as that formed in water. An acetonitrile molecule found in the substrate binding site of the free enzyme is displaced in the acyl-enzyme, while a second acetonitrile continues to occupy the site of the nucleophilic water in the aqueous structure. Crystals soaked in acetonitrile for long periods, or those that are air dried, have low active site contents (by phenylmethanesulfonyl fluoride [PMSF] titration) and become impermeable to a tracer dye. The authors emphasize the importance of the supramolecular structure of the crystals.
-
(1998)
Proc Natl Acad Sci USA
, vol.95
, pp. 12918-12923
-
-
Schmitke, J.L.1
Stern, L.J.2
Klibanov, A.M.3
-
33
-
-
0031958027
-
Physical characterization of porous materials and correlation with the activity of immobilized enzyme in organic medium
-
Barros R.J., Wehtje E., Garcia F.A.P., Adlercreutz P. Physical characterization of porous materials and correlation with the activity of immobilized enzyme in organic medium. Biocatal Biotrans. 16:1998;67-85.
-
(1998)
Biocatal Biotrans
, vol.16
, pp. 67-85
-
-
Barros, R.J.1
Wehtje, E.2
Garcia, F.A.P.3
Adlercreutz, P.4
-
34
-
-
0032486748
-
Mass transfer studies on immobilized alpha-chymotrypsin biocatalysts prepared by deposition for use in organic medium
-
Evidence is presented that preparations made by co-drying can show internal mass transfer limitation at high loading: saturating reaction rates at high loading; and increased specific activity on dilution with enzyme inactivated using tosyl-phenylalanine chloromethylketone.
-
Barros R.J., Wehtje E., Adlercreutz P. Mass transfer studies on immobilized alpha-chymotrypsin biocatalysts prepared by deposition for use in organic medium. Biotechnol Bioeng. 59:1998;364-373. Evidence is presented that preparations made by co-drying can show internal mass transfer limitation at high loading: saturating reaction rates at high loading; and increased specific activity on dilution with enzyme inactivated using tosyl-phenylalanine chloromethylketone.
-
(1998)
Biotechnol Bioeng
, vol.59
, pp. 364-373
-
-
Barros, R.J.1
Wehtje, E.2
Adlercreutz, P.3
-
35
-
-
0032002508
-
Surface active substrates essential in lipase mediated esterifications in foams
-
Aqueous media containing 100 mM oleic acid and n-alcohols a lipase are foamed by aeration, leading to up to 75% esterification.
-
Rao N.M., Haribabu M. Surface active substrates essential in lipase mediated esterifications in foams. Langmuir. 14:1998;738-740. Aqueous media containing 100 mM oleic acid and n-alcohols a lipase are foamed by aeration, leading to up to 75% esterification.
-
(1998)
Langmuir
, vol.14
, pp. 738-740
-
-
Rao, N.M.1
Haribabu, M.2
-
36
-
-
0032074323
-
Enzymatic glyceride synthesis in a foam reactor
-
Lauric acid in a 50% glycerol-water medium could be efficiently esterified with lipase catalysis, by aerating and forming a large foam volume.
-
Yeh Y.C., Gulari E. Enzymatic glyceride synthesis in a foam reactor. J Amer Oil Chem Soc. 75:1998;643-650. Lauric acid in a 50% glycerol-water medium could be efficiently esterified with lipase catalysis, by aerating and forming a large foam volume.
-
(1998)
J Amer Oil Chem Soc
, vol.75
, pp. 643-650
-
-
Yeh, Y.C.1
Gulari, E.2
-
37
-
-
0032590343
-
Characterisation of acylglycerol synthesis in aqueous foams by lipases
-
Shanmugam V.M., Sasikumar P.G., Rao N.M. Characterisation of acylglycerol synthesis in aqueous foams by lipases. J Chem Technol Biotechnol. 74:1999;515-518.
-
(1999)
J Chem Technol Biotechnol
, vol.74
, pp. 515-518
-
-
Shanmugam, V.M.1
Sasikumar, P.G.2
Rao, N.M.3
-
38
-
-
0032487739
-
A novel approach to biotransformations in aqueous-organic two-phase systems: Enzymatic synthesis of alkyl beta-[D]-glucosides using microencapsulated beta-glucosidase
-
The enzyme and glucose substrate were in an aqueous phase trapped inside a polymeric capsule membrane. The capsules were then suspended in neat hexanol or octanol substrates. Stability is better than for a support-adsorbed enzyme.
-
Yi Q., Sarney D.B., Khan J.A., Vulfson E.N. A novel approach to biotransformations in aqueous-organic two-phase systems: enzymatic synthesis of alkyl beta-[D]-glucosides using microencapsulated beta-glucosidase. Biotechnol Bioeng. 60:1998;385-390. The enzyme and glucose substrate were in an aqueous phase trapped inside a polymeric capsule membrane. The capsules were then suspended in neat hexanol or octanol substrates. Stability is better than for a support-adsorbed enzyme.
-
(1998)
Biotechnol Bioeng
, vol.60
, pp. 385-390
-
-
Yi, Q.1
Sarney, D.B.2
Khan, J.A.3
Vulfson, E.N.4
-
39
-
-
0000800173
-
Reinforced protein crystals
-
Lysozyme crystals grown in silica gels incorporate large amounts of silica, and have improved mechanical and chemical stability, but still have ordered protein, as shown here by X-ray diffraction.
-
Garcia-Ruiz J.M., Gavira J.A., Otalora F., Guasch A., Coll M. Reinforced protein crystals. Materials Res Bull. 33:1998;1593-1598. Lysozyme crystals grown in silica gels incorporate large amounts of silica, and have improved mechanical and chemical stability, but still have ordered protein, as shown here by X-ray diffraction.
-
(1998)
Materials Res Bull
, vol.33
, pp. 1593-1598
-
-
Garcia-Ruiz, J.M.1
Gavira, J.A.2
Otalora, F.3
Guasch, A.4
Coll, M.5
-
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Subtilisin was covalently attached to a methacrylate co-polymer containing spiropyran groups. The modified enzyme was soluble and active in toluene, but was precipitated by ultraviolet irradiation, which changed the spiropyran to merocyanine groups. Visible irradiation reversed the process.
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Ito Y., Sugimura N., Kwon O.H., Imanishi Y. Enzyme modification by polymers with solubilities that change in response to photoirradiation in organic media. Nat Biotechnol. 17:1999;73-75. Subtilisin was covalently attached to a methacrylate co-polymer containing spiropyran groups. The modified enzyme was soluble and active in toluene, but was precipitated by ultraviolet irradiation, which changed the spiropyran to merocyanine groups. Visible irradiation reversed the process.
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Secundo F., Spadaro S., Carrea G., Overbeeke P.L.A. Optimization of Pseudomonas cepacia lipase preparations for catalysis in organic solvents. Biotechnol Bioeng. 62:1999;554-561. The lipase was prepared in different ways and rates of transesterification and competing hydrolysis determined in carbon tetrachloride, benzene and dioxane at known water activity. Specific activity (per unit protein) was at least 10-fold better for a silica-entrapped (sol-gel process) enzyme than for lyophilised powders or cross-linked crystals.
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The performance of solid substrate suspensions can be improved compared with a reaction system in which substrates are totally dissolved, because the concentration of the favoured enantiomer need not fall as the reaction proceeds. In particular, a given enantiomeric excesses of unreacted substrate can be obtained with a higher yield.
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Wolff A., van Asperen V., Straathof A.J.J., Heijnen J.J. Potential of enzymatic kinetic resolution using solid substrates suspension: improved yield, productivity, substrate concentration, and recovery. Biotechnol Prog. 15:1999;216-227. The performance of solid substrate suspensions can be improved compared with a reaction system in which substrates are totally dissolved, because the concentration of the favoured enantiomer need not fall as the reaction proceeds. In particular, a given enantiomeric excesses of unreacted substrate can be obtained with a higher yield.
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