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Comparison of hydrolysis and esterification behavior of Humicola lanuginosa and Rhizomucor miehei lipases in AOT-stabilized water-in-oil microemulsions: II. Effect of temperature on reaction kinetics and general considerations of stability and productivity (1995)

Crooks, Gavin E. ; Rees, Gareth D. ; Robinson, Brian H. ; [et al.]

New York, NY [u.a.] : Wiley-Blackwell

Biotechnology and Bioengineering 48 (1995), S. 190-196

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ISSN: 0006-3592

Keywords: hydrolysis ; esterification ; Humicola lanuginosa ; Rhizomucor miehei ; Chemistry ; Biochemistry and Biotechnology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology

Notes: Humicola lanuginosa lipase (HIL) and Rhizomucor miehei lipase (RrnL), isolated from commercial preparations of Lipolase and Lipozyme, respectively, were solubilized in AOT-stabilized water-in-oil (w/o) microemulsions in n-heptane and aspects of their hydrolysis and condensation activity examined. The temperature dependence of HIL hydrolysis activity in unbuffered R = 10 microemulsions matched very closely that for tributyrin hydrolysis by Lipolase in an aqueous emulsion assay. Apparent activation energies were measured as 13 ± 2 and 15 ± 2 kJ mol / respectively. Condensation activity, however, was essentially independent of temperature over the range 5° to 37°C. The stability of HIL over a 30-day period was very good at all pH levels (6.1, 7.2, 9.3) and R values studied (5, 7.5, 10, 20), except when high pHs and low R values were combined. The excellent stability was reflected by the linearity of the productivity profiles which facilitate system optimization. The temperature dependence of RmL hydrolysis activity toward pNPC4 showed a maximum at 40°C and an apparent Eact = 20 ± 2 kJ mol-1 was calculated based on the linear region of the profile (5° to 40°C). RmL esterification activity showed only a slight dependence on temperature over the studied range (0° to 40°C) and an apparent Eact = 5 ± 1 kJ mol-1 was measured for octyl decanoate synthesis. Both RmL and HIL, therefore, have potential for application in low temperature biotransformations in microemulsion-based media. The stability of RmL over a 30-day period was good in R = 7.5 and R = 10 microemulsions containing pH 6.1 buffer, and this was reflected in the linearity of their respective productivity profiles. RmL stability was markedly poorer at more alkaline pH, however, and proved to be sensitive to relatively small changes in the R value. © 1995 John Wiley & Sons, Inc.

Additional Material: 10 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/bit.260480304

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Comparison of hydrolysis and esterification behavior of Humicola lanuginosa and Rhizomucor miehei lipases in AOT-stabilized water-in-oil microemulsions: I. Effect of pH and water content on reaction kinetics (1995)

Crooks, Gavin E. ; Rees, Gareth D. ; Robinson, Brian H. ; [et al.]

New York, NY [u.a.] : Wiley-Blackwell

Biotechnology and Bioengineering 48 (1995), S. 78-88

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ISSN: 0006-3592

Keywords: hydrolysis ; esterification ; Humicola lanuginosa ; Rhizomucor miehei ; Chemistry ; Biochemistry and Biotechnology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology

Notes: Lipolase and Lipozyme are produced in large quantities (as a result of genetic engineering and overexpression) for the detergents market and provide a cheap source of highly active biocatalysts. Humicola lanuginosa lipase (HIL) and Rhizomucor miehei lipase (RmL) have been isolated in partially purified form from commercial preparations of Lipolase and Lipozyme, respectively. These lipases were solubilized in Aerosol-OT (AOT)-stabilized water-in-oil (w/o) microemulsions in n-heptane. HIL and RmL activity in these microemulsions was assayed by spectrophotometric measurement of the initial rate of p-nitophenyl butyrate hydrolysis, and by chromatographic determination of the initial rate of octyl decanoate synthesis from 1-octanol and decanoic acid. The hydrolytic activity of HIL in microemulsions measured as a function of buffer pH prior to dispersal, followed a sigmoidal profile with the highest activities observed at alkaline pHs. This broadly matches the pH-activity profile for tributyrin hydrolysis by Lipolase in an aqueous emulsion assay. The hydrolytic activity of RmL in the same microemulsions, measured as a function of pH, gave a bell-shaped profile with a maximum activity at pH 7.5. Again, the observed pH-activity profile was similar to that reported for a purified RmL in a tributyrin-based aqueous emulsion assay. In contrast, the esterification activity exhibited by both HIL and RmL in AOT microemulsions over the available range pH 6.1 to 10.4, decreases as the pH increases, most likely reflecting the effect of substrate ionization. The dependence of the hydrolytic and condensation activity of HIL on R, the mole ratio of water to surfactant, were similar with both profiles exhibiting a maximum at R = 5. The hydrolytic and esterification activities of RmL followed similar R-dependent profiles, but the profiles in this case exhibited a maximum at R = 10. The water activities at these R values were directly measured as 0.78 and 0.9, respectively. Measured water activities were unperturbed by the presence of lipase at the concentrations used in these studies. © 1995 John Wiley & Sons, Inc.

Additional Material: 14 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/bit.260480111

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Substituent-induced chemical shifts along C=C double bondsSterically Congested Molecules, Part 8. For Part 7, see Ref. 6. (1993)

Knorr, Rudolf ; von Roman, Therese ; Freudenreich, Johannes ; [et al.]

Chichester : Wiley-Blackwell

Organic Magnetic Resonance 31 (1993), S. 557-565

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ISSN: 0749-1581

Keywords: 13C NMR ; 1H NMR Olefins ; Substituent effects ; Substituent-induced chenical shifts (SCS) ; Chemistry ; Analytical Chemistry and Spectroscopy

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: 1H and 13C NMR signals were assigned and CH coupling constants (1J, 2J, 3J) determined for a series of α-mono-and α,α-disubstituted (1,1,3,3-tetramethyl-2-indanylidene)methanes with the following α-substituents: (mesityl)2B, n-propyl, phenyl, tert-butyl-C(=NH), cyano, (tert-butyl)2C(OH), pivaloyl, H2N-CO, PhNH-CO, carboxy, ritro, acetoxy, Me3SiO, Me3Si, PhS, PhSMe+, PhSO, PhSO2, bromo and trimethylstannyl. The 1J couplings with the olefinic proton span the range 124.3-193.7 Hz. Substituent-induced chemical shifts (SCS) of most of the nuclei with respect to the α-unsubstituted olefin obey simple additivity in the α,α-disubstituted compounds and are very similar to the SCS values along the C=N double bond in the isoelectronic (1,1,3,3-tetramethyl-2-indanylidene)amines within the error limits. The exceptions concern nuclei in the immediate vicinity of the perturbing substituent. A dominant mechanistic contribution of electric field effects appears likely for the more distant aromatic part of the indanylidene moiety. The chemical shifts of two (2,2,5,5-tetramethylcyclopentylidene)methanes are shown to be compatible with the SCS parameters from the indanylidene series.

Additional Material: 2 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/mrc.1260310608

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