| 1. |
- Adlercreutz, Patrick, et al.
(författare)
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Enzymatic conversions of polar lipids. Principles, problems and solutions
- 2001
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Ingår i: Journal of Molecular Catalysis - B Enzymatic. - 1381-1177. ; 11:4-6, s. 173-178
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Forskningsöversikt (refereegranskat)abstract
- This text provides a brief overview of the principles of enzymatic lipid conversion and some recent advances in the enzymatic conversion of glycerophospholipids and galactolipids. Lipases and phospholipases are used to exchange fatty acids or the polar group in the lipids. The reactions can be carried out either as hydrolysis-esterification sequences or as one-step transferase reactions. The scope and limitations of the different methods are discussed.
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| 2. |
- Adlercreutz, Patrick, et al.
(författare)
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Enzymatic fatty acid exchange in glycerophospholipids
- 2003
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Ingår i: European Journal of Lipid Science and Technology. - : Wiley. - 1438-7697 .- 1438-9312. ; 105:10, s. 638-645
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Forskningsöversikt (refereegranskat)abstract
- Lipases can be used to exchange fatty acids in the sn-1 position of glycerophospholipids and phospholipase A2 is useful for the corresponding exchange reaction in the sn-2 position. In both cases, the exchange can be done in a one-step acidolysis process or in a two-step process. In the latter case, the original fatty acid in the desired position is removed by enzymatic hydrolysis or alcoholysis and after isolation of the resulting lysophospholipid, the new fatty acid is introduced, using the same enzyme, in an esterification reaction. Several synthesis examples from the literature are reviewed. Incorporation of a new fatty acid into the sn-1 position is more favourable than incorporation into the sn-2 position because of the magnitudes of the equilibrium constants of the reactions and because lipases can be used at much lower water activity than phospholipase A2. With the consecutive use of both enzymes highly pure products with defined fatty acids in both positions can be obtained.
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| 3. |
- Lyberg, Ann-Marie, et al.
(författare)
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Enzymatic and chemical synthesis of phosphatidylcholine regioisomers containing eicosapentaenoic acid or docosahexaenoic acid
- 2005
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Ingår i: European Journal of Lipid Science and Technology. - : Wiley. - 1438-7697 .- 1438-9312. ; 107:5, s. 279-290
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Tidskriftsartikel (refereegranskat)abstract
- Regioselective incorporation of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) into phosphatidylcholine (PC) was carried out using enzymatic and chemical synthesis. Incorporation at the sn-1 position was successfully achieved by lipase-catalysed esterification of 2-palmitoyl-lysophosphatidylcholine (LPC), although in most cases, the enzymes incorporated EPA and DHA at lower rates than other fatty acids. For the incorporation of DHA, Candida antarctica lipase B was the only useful enzyme, while incorporation of EPA was efficiently carried out using either this enzyme or Rhizopus arrhizus lipase. The highest yields in the lipase-catalysed reactions were obtained at the lowest water activity (close to 0). However, by carrying out the reactions at a higher water activity of 0.22, more EPA and DHA were incorporated. Esterification of 2-palmitoyl-LPC with pure EPA at this water activity converted 66 mol-% of LPC to PC using Rhizopus arrhizus lipase as catalyst. When the fatty acid was DHA and the catalyst Candida antarctica lipase B, 45 mol-% of PC was obtained. For incorporation of EPA and DHA at the sn-2 position, phospholipase A(2) was used, but the reaction was very slow. Chemical coupling of 1 -palmitoyl-LPC and EPA or DHA was more efficient, resulting in complete conversion of LPC.
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| 4. |
- Mbatia, Betty, et al.
(författare)
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Enzymatic oil extraction and positional analysis of omega-3 fatty acids in Nile perch and salmon heads
- 2010
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Ingår i: Process Biochemistry. - : Elsevier BV. - 1873-3298 .- 1359-5113. ; 45:5, s. 815-819
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Tidskriftsartikel (refereegranskat)abstract
- The use of commercial proteases, bromelain and Protex 30L for oil extraction/recovery of polyunsaturated fatty acids (PUFA) from Nile perch and salmon heads was evaluated. Four phases were obtained after hydrolysis, oily phase, emulsion, aqueous phase and sludge. An increase in water content during the hydrolysis resulted in a decrease in oil yield. Maximum oil yield was obtained when hydrolysis was performed with Protex 30L at 55 C, without pH adjustment or water addition. An oil yield of 11.2% and 15.7% of wet weight was obtained from Nile perch and salmon heads, respectively, compared to 13.8% and 17.6%, respectively obtained using solvent extraction. Fatty acid distribution analysis showed 50% of palmitic acid was in sn-2 position in Nile perch triglycerides (TAG), while only 16% of this fatty acid was in sn-2 position in salmon oil TAG. (C) 2010 Elsevier Ltd. All rights reserved.
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| 5. |
- Adlercreutz, Dietlind, et al.
(författare)
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An enzymatic method for the synthesis of mixed-acid phosphatidylcholine
- 2004
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Ingår i: Journal of the American Oil Chemists Society. - : Wiley. - 0003-021X. ; 81:6, s. 553-557
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Tidskriftsartikel (refereegranskat)abstract
- The enzymatic synthesis of PC with decanoic acid in the sn-1 and hexanoic acid in the sn-2 position is described. The procedure comprises the following enzymatic steps: (i) treatment of egg yolk with phospholipase A(2) (PLA(2)) to hydrolyze egg yolk PC to 1-acyl lysophosphaticlylcholine (LPC) (ii) esterification of I-acyl LPC with hexanoic acid catalyzed by PLA(2) to yield PC with hexanoic acid in the sn-2 position; (iii) removal of the FA in the sn-1 position by lipase-catalyzed ethanolysis to yield 2-hexanoyl LPC; and finally (iv) introduction of decanoic acid in this position by lipase-catalyzed esterification of 2-hexanoyl LPC to yield 1-decanoyl-2-hexanoyl-PC. Two egg yolks with a weight of 16 g were required to obtain 160 mg of the desired product. The chemical purity of the PC product and the positional purity of the FA were around 99%. The method is applicable for the synthesis of other mixed-acid PC species as well.
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| 6. |
- Adlercreutz, Dietlind
(författare)
-
Enzymatic Synthesis of Mixed Acid Phospholipids
- 2002
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Mixed acid phospholipids are valuable compounds, which are used mainly in membrane- and lipoprotein research and in liposome technology. The chemical synthesis of these special lipids is rather difficult and involves both toxic chemicals and harsh reaction conditions, which makes the products less attractive for medical and biological applications. Enzymes in contrast catalyze chemical reactions under mild conditions, providing a promising alternative to the traditional chemical approach. In the thesis 1,3 specific lipases and phospholipase A2 have been applied in order to incorporate fatty acids specifically into the sn-1 and sn-2 position respectively. The phospholipase A2-catalyzed esterification of 1-acyl lysophosphatidylcholine with oleic acid to produce phosphatidylcholine with oleic acid in the sn-2 position was studied in toluene under water activity controlled conditions. The aim of the study was to find the conditions most favorable for the synthesis reaction. To do this the impact of various reaction parameters such as water activity, substrate concentration and temperature on enzyme activity and equilibrium yield was determined. The phosphatidylcholine to lysophosphatidylcholine ratio at equilibrium increased with decreasing water activity and increasing fatty acid concentration, as can be expected from the law of mass action of an esterification reaction. The enzyme activity on the other hand decreased under conditions that favor the esterification. The best yield in the synthesis reaction was 60% at a water activity of 0.11 and an oleic acid concentration of 1.8 M. 1,3 specific lipases were employed to introduce caproic acid into the sn-1 position of phosphatidylcholine. The reaction was carried out in either one step (transesterification reaction) or in two steps (ethanolysis and re-esterification). A comparison between these two reaction modes was made with regard to product yield, product purity, reaction time, and by-product formation as a consequence of acyl migration. Esterification and transesterification reactions were studied in toluene under water activity controlled conditions. The yield in both types of reactions was the same under identical conditions. The highest yield (78%) was obtained at a water activity of 0.11 and a caproic acid concentration of 0.8 M. The reaction time was shorter in the esterification than in the transesterification reaction. The difference in reaction time was especially pronounced at low water activities and high fatty acid concentrations. The loss due to acyl migration was around 16% under a wide range of conditions. The incorporation of a fatty acid into the sn-1 position proved to be thermodynamically more favorable than the incorporation of a fatty acid into the sn-2 position. By a combination of lipase and phospholipase A2 action it was possible to convert egg yolk phosphatidylcholine, containing various fatty acids into phosphatidylcholine with capric acid in the sn-1 position and caproic acid in the sn-2 position. Two egg yolks with a weight of 16 g were required in order to obtain 160 mg of the desired product.
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| 7. |
- Adlercreutz, Dietlind, et al.
(författare)
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Synthesis of phosphatidylcholine with defined fatty acid in the sn-1 position by lipase-catalyzed esterification and transesterification reaction.
- 2002
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Ingår i: Biotechnology and Bioengineering. - : Wiley. - 1097-0290 .- 0006-3592. ; 78:4, s. 403-411
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Tidskriftsartikel (refereegranskat)abstract
- The incorporation of caproic acid in the sn-1 position of phosphatidylcholine (PC) catalyzed by lipase from Rhizopus oryzae was investigated in a water activity-controlled organic medium. The reaction was carried out either as esterification or transesterification. A comparison between these two reaction modes was made with regard to product yield, product purity, reaction time, and byproduct formation as a consequence of acyl migration. The yield in the esterification and transesterification reaction was the same under identical conditions. The highest yield (78%) was obtained at a water activity (a(w)) of 0.11 and a caproic acid concentration of 0.8 M. The reaction time was shorter in the esterification reaction than in the transesterification reaction. The difference in reaction time was especially pronounced at low water activities and high fatty acid concentrations. The loss in yield due to acyl migration and consequent enzymatic side reactions was around 16% under a wide range of conditions. The incorporation of a fatty acid in the sn-1 position of PC proved to be thermodynamically much more favorable than the incorporation of a fatty acid in the sn-2 position.
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| 8. |
- Egger, Dietlind, et al.
(författare)
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Characterization and optimization of phospholipase A2 catalyzed synthesis of phosphatidylcholine
- 1997
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Ingår i: BBA - Protein Structure and Molecular Enzymology. - 0167-4838. ; 1343:1, s. 76-84
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Tidskriftsartikel (refereegranskat)abstract
- The phospholipase A2 (PLA2) catalyzed synthesis and hydrolysis of phosphatidylcholine (PC) was studied in a water activity controlled organic medium. The aim of the study was to find the conditions most favorable for the synthetic reaction. To do this, the impact of various parameters such as water activity, substrate concentration and temperature on enzyme activity and equilibrium yield was determined. The PC to lysophosphatidylcholine (LPC) ratio at equilibrium increases with decreasing water activity and increasing fatty acid concentration, as can be expected from the law of mass action of an esterification reaction. The enzyme activity on the other hand decreases under conditions that favor the esterification. The best yield in the synthetic reaction is 60% at a water activity of 0.11 and an oleic acid concentration of 1.8 M. That is to our knowledge the highest yield ever reported in this reaction. Both the hydrolysis and synthesis reaction follow Michaelis-Menten kinetics, the apparent K(m) values are the same for PC and LPC, namely 4.9 mM. V(max) is 82.5 and 10.4 nmol h-1 mg-1 for the hydrolysis and synthesis reaction, respectively. Studies on PLA2 at water activity controlled conditions resulted in a more complete understanding of the enzymatic reaction and allowed to find the conditions most favorable for the synthetic reaction.
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| 9. |
- Orellana-Coca, C, et al.
(författare)
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Chemo-enzymatic epoxidation of oleic acid and methyl oleate in solvent-free medium
- 2005
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Ingår i: Biocatalysis and Biotransformation. - : Informa UK Limited. - 1024-2422 .- 1029-2446. ; 23:6, s. 431-437
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Tidskriftsartikel (refereegranskat)abstract
- Chemo-enzymatic epoxidation of oleic acid (OA) and its methyl ester has been performed using hydrogen peroxide and immobilized lipase from Candida antarctica (Novozym(R) 435). The purpose of the study was to characterize the reaction under solvent-free conditions. The reaction temperature had a significant impact on epoxidation of OA. At lower temperatures, the substrate conversion was hindered by the formation of solid epoxystearic acid product. Nearly 90% conversion of OA to the epoxide product was obtained after 6 h at 50 degrees C. Longer reaction times at 40 degrees C and above resulted in by-product formation and eventually lowered the product yield. In contrast, the reaction with methyl oleate (MO) was less influenced by temperature. Almost complete epoxidation was achieved at 40-60 degrees C, the higher the temperature the shorter was the reaction time. The main epoxidation product obtained was epoxystearic acid methyl ester (EME), and the remaining was epoxystearic acid (EA) formed by the hydrolytic action of the lipase. Recycling of the lipase for epoxidation of MO at 50 degrees C indicated that the immobilized enzyme was prone to activity loss.
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| 10. |
- Orellana Coca Åkerman, Cecilia, et al.
(författare)
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Analysis of fatty acid epoxidation by high performance liquid chromatography coupled with evaporative light scattering detection and mass spectrometry
- 2005
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Ingår i: Chemistry and Physics of Lipids. - : Elsevier BV. - 0009-3084. ; 135:2, s. 189-199
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Tidskriftsartikel (refereegranskat)abstract
- Conventionally, epoxidation of unsaturated fatty acids has been studied either with titrimetric methods or in a lengthy procedure involving derivatization followed by gas chromatography (GC). We have developed a more rapid and descriptive analysis procedure for the substances using high performance liquid chromatography (HPLC) with evaporative light scattering detection (ELSD). Chemo-enzymatic epoxidation of unsaturated fatty acids (oleic, linoleic and linolenic acid, respectively) has been performed using hydrogen peroxide and immobilized lipase from Candida antarctica (Novozym 435). The fatty acids and their epoxidation products were separated by HPLC on a C-18 reversed-phase column using methanol-water containing 0.05% acetic acid as mobile phase. The method facilitated the simultaneous determination of fatty acids and epoxides differing from each other in the number of epoxide rings, the degree of unsaturation and the position of the epoxide rings and double bonds. An important aspect of the method development was the use of electrospray ionization and tandem mass spectrometry to confirm the structure of the epoxide products. It is suggested that the HPLC method, providing more information about the kind and concentration of fatty acids and their epoxides, represents a powerful complement to the existing methods for monitoring epoxidation processes on fatty acids. (c) 2005 Elsevier Ireland Ltd. All rights reserved.
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