Enzyme-catalysed Lipid Modification

Adlercreutz, Patrick

doi:10.1080/02648725.1994.10647913

Cited by 29 publications

(7 citation statements)

References 88 publications

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“…When molecular sieves were added to the reaction mixture the water content decreased and the yield was 100%. The equilibrium constant (K 0 ), expressed in [1] units of M −1 , can be calculated using the concentrations of substrates/product and the water activity according to Valivety et al (16). This constant sharply increases as the a w of the system decreases (Table 1).…”

Section: Resultsmentioning

confidence: 99%

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Continuous lipase‐catalyzed production of wax ester using silicone tubing

Wehtje

Costes

Adlercreutz

1999

J Americ Oil Chem Soc

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Enzymatic synthesis of cetyl palmitate was performed in a solvent-free system at 65°C using immobilized Candida antarctica lipase. Batch reactions at controlled water activity showed that the yield could be increased from 88.8 to 99.1% by decreasing the water activity from 1 to 0.05. A continuous reactor configuration was constructed, where two tubular reactors were run in sequence with a separation container in between, in which the water phase was separated from the wax ester phase. The reactor was run for 1 wk at low flow rate (0.005 g/min) with very good operational stability and a productivity of 7.2 g d −1 using 0.4 g of biocatalyst. The activity of the individual preparations decreased during operation. The first reactor had only 30% activity left after 1 wk of operation whereas the second reactor showed only a 10% decrease. This difference in enzyme stability is a direct result of the different water activity in the two reactors.Paper no. J9174 in JAOCS 76, 1489 -1493 (December 1999.KEY WORDS: Nonaqueous media, operational stability, packed-bed reactor, water activity.Lipase-catalyzed esterification is one of the most studied reactions in biocatalysis (1-3). Many enzymatic methods for the production of esters have been described over the last decade (4-7). Moderate reaction conditions, specificity, and high product purity make the biocatalytic routes attractive compared to classical chemical processes. However, the relatively low stability of enzyme must be overcome before lipases become widely used as catalysts in industrial applications. The water formed during the esterification reaction will change the equilibrium position, influence the reaction rate, and reduce enzyme stability. To obtain high thermodynamic conversion and high reaction rate while preventing enzyme deactivation, nearly dry conditions are normally required throughout the reaction. It is important therefore that an enzymatic process include removal of water from the reaction mixture. Toward this goal, different methods of water removal have been proposed. Zacharis et al. (8) controlled water content by using salt hydrate pairs. Trani et al. (9) developed an open batch reactor with water evaporation at atmospheric pressure while Eigtved et al. (10) used a slight vacuum (0.05 atm) to remove the water generated. Recently, Colombié et al. (11) tried to use a hydrophilic solvent in the reaction mixture to solubilize the water formed. Mensah et al.(12) used a cation exchange resin as a selective water adsorbent. In the present study, we propose a new application of our previously developed water control procedure using silicone tubing (13-15) for the continuous lipase-catalyzed production of wax esters in a solvent-free system. MATERIALS AND METHODS Enzyme preparation. Immobilized lipase SP 435 (Novozyme) from Candida antarctica was generously donated by Novo Nordisk A/S (Bagsvaerd, Denmark).Tubing. The silicone tubing, 5.0 mm outer and 3.0 mm inner diameter, was from Leewood Marketing AB (Stockholm, Sweden). The polyvinylchloride (PVC) tub...

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Section: Resultsmentioning

confidence: 99%

“…Lipase-catalyzed esterification is one of the most studied reactions in biocatalysis (1)(2)(3). Many enzymatic methods for the production of esters have been described over the last decade (4)(5)(6)(7).…”

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confidence: 99%

Continuous lipase‐catalyzed production of wax ester using silicone tubing

Wehtje

Costes

Adlercreutz

1999

J Americ Oil Chem Soc

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“…), with important applications in the synthesis of peptides (Schellenberger and Jakubke, 1991), lipids (Adlercreutz, 1994), glycosides (van Rantwijk et al, 1999), and oligosaccharides (Bucke, 1996). Enzymes catalyzing only these kinds of reactions are called transferases, and the ones transferring a glycosyl group are glycosyl transferases.…”

Section: Introductionmentioning

confidence: 99%

Enhanced transglucosylation/hydrolysis ratio of mutants of Pyrococcus furiosus β‐glucosidase: Effects of donor concentration, water content, and temperature on activity and selectivity in hexanol

Hansson¹,

Adlercreutz²

2001

Biotech & Bioengineering

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The transglucosylation reaction catalyzed by wild-type beta-glucosidase CelB from hyperthermophilic Pyrococcus furiosus and active site mutants (M424K, F426Y, M424K/F426Y) was studied. The conversion of pentyl-beta-glucoside to hexyl-beta-glucoside in hexanol was used as a model transglucosylation reaction. Hydrolysis to glucose was a side reaction. The selectivity towards transglucosylation was quantified by the S value defined as follows: S = r(S) x a(W)/r(H) x a(hex) where r(S) and r(H) are the initial rates of transglucosylation and hydrolysis and a(w) and a(hex) are the thermodynamic activities of water and hexanol. The activity (rates of hydrolysis and transglucosylation) and the selectivity (S value) were measured as a function of pentyl-beta-glucoside concentration (5-240 mM), water content (1-100% v/v), and temperature (50-95 degrees C). All mutants had lower activity than the wild-type enzyme, but they had higher selectivity, which means that they provided a higher ratio of transglucosylation product to hydrolysis product. The largest increase in S-value (2.6 fold) was obtained by the F426Y mutant, which resulted in increased hexyl-beta-glucoside yield from 56% to 69%. In addition, the F426Y enzyme had higher selectivity over the wide range of temperatures tested. The activity of CelB wild-type and CelB F426Y increased as a function of water activity (a(w)), and complete activation by the water was obtained in a two-phase system with 20% water phase. In contrast to CelB wild-type, the F426Y mutant had transferase activity as low as a(w) = 0.29. Surprisingly, the S value increased with increasing water activity up to a(w) = 0.92. At still higher water content the S value decreased.

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“…with lipases from Rhizomucor miehei (RML), Aspergillus niger, and A. oryzae) has been developed for the cheese-manufacturing industry [9][10][11][12]. The potential of 1,3-specific lipases for the manufacture of structured triacylglycerols, such as cocoa butter substitutes [10,[13][14][15][16] or as a formula additive for premature infants (Betapol), was clearly recognized. Lipases are also being intensively investigated with regard to the modification of oils rich in high-value polyunsaturated fatty acids such as arachidonic, eicosapentaenoic, docosahexaenoic, and some others.…”

Section: Introductionmentioning

confidence: 99%