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1

Enzymatyczne i chemiczne modyfikacje fosfolipidów

Chojnacka Anna, Niezgoda Natalia

Wiadomości Chemiczne

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2023

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[Z] 77, 5-6

449--477

EN

At the moment, phospholipids are among the most interesting molecules. The possibilities of chemical and enzymatic modifications, while maintaining their integrity and unique nature, also contribute to these compounds' great interest. This review paper concerns the preparation of new phospholipid conjugates containing fragments of biologically active compounds not found naturally in phospholipids, and phospholipids enriched with specific fatty acids with health-promoting properties (structured phospholipids). Chemical methods for the synthesis of phospholipids containing conjugated linolenic acid (CLA), dehydroepiandrosterone (DHEA) or selected non-steroidal anti-inflammatory drugs (NSAIDs) at the sn-1 and/or sn-2 position have been described. In addition, the evaluation of the antiproliferative activity of the obtained conjugates against selected cancer cell lines was also described. Enzymatic methods of modifying natural phospholipids leading to their enrichment with bioactive polyunsaturated fatty acids and conjugated acids have also been described.

2

Synthesis of isoamyl acetate using protein-coated microcrystals of different lipases

Türk Murat

Polish Journal of Chemical Technology

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2023

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Vol. 25, nr 2

15--20

EN

The goal of this study was the immobilization of different lipases as protein-coated microcrystals on K2SO4 and their uses in the synthesis of isoamyl acetate in n-hexane medium. The optimum conditions, such as lipase variety, temperature, the initial molar ratio of vinyl acetate/isoamyl alcohol, immobilized lipase amount, and reaction time were determined. The highest conversion was obtained when protein-coated microcrystals of Thermomyces lanuginosus lipase (TLL-PCMCs) was used for the synthesis of isoamyl acetate. The optimum temperature, the initial molar ratio of vinyl acetate/isoamyl alcohol, immobilized lipase amount, and reaction time were determined to be 50 °C, 3.0, 30 mg, and 360 min, respectively. Under the optimized conditions, isoamyl acetate yield was obtained as 95%. TLL-PCMCs retained 90% of their initial activity after five repeat use in the isoamyl acetate synthesis. TLL-PCMCs may be used in the preparation of industrially important aroma compounds due its ease of preparation and efficiency.

3

Wyznaczanie energii aktywacji oraz optymalnej temperatury reakcji hydrolizy palmitynianu p-nitrofenylu katalizowanej przez lipazy

Miłek Justyna

Przemysł Chemiczny

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2021

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T. 100, nr 1

103--104

PL

Na podstawie modelu matematycznego opisującego wpływ temperatury na aktywność lipaz z Rhizopus oryzae 3562 oraz Enterobacter aerogenes wyznaczono energie aktywacji Ea i dezaktywacji Ed oraz optymalne temperatury Topt procesu hydrolizy palmitynianu p-nitrofenylu (p-NPP). Wartości Ead, Topt wynosiły odpowiednio 32,86±14,86 kJ/mol, 59,74±8,72 kJ/mol i 298,02 ± 3,02 K dla lipazy R. oryzae 3562 oraz 45,37 ± 16,28 kJ/mol, 59,28 ± 14,07 kJ/mol i 295,00 ± 2,74 K dla lipazy E. aerogenes. Założono, że reakcje hydrolizy p-NPP katalizowane przez badane lipazy przebiegały zgodnie z kinetyką pierwszego rzędu ze względu na stężenie enzymu.

EN

Exptl. data on the temp. relationship of lipases from Rhizopus oryzae 3562 and Enterobacter aerogenes activity published by Kumari et al. (2008), were used to calc. the optimum temp., activation energies and deactivation energies of the p-nitrophenyl palmitate hydrolysis according a resp. math. model of the reaction. The calcd. values were 298.02±3.02 K, 32.86±14.86 kJ/mol and 59.74±8.72 kJ/mol for lipase from R. oryzae 3562 and 295.00 ± 2.74 K, 45.37 ± 16.28 kJ/mol and 59.28 ± 14.07 kJ/mol for lipase from E. aerogenes.

4

The activation energies and optimum temperatures of olive oil hydrolysis by lipase porcine pancreas

Miłek Justyna

Ecological Chemistry and Engineering. S

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2021

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Vol. 28, nr 3

389--398

EN

Lipase activity is a perfect indicator for the monitoring of processes of bioremediation of degraded soils. Lipase is also used in the processes of oil hydrolysis in wastewater treatment. To be able to predict and model processes with used lipase in environmental operations, knowledge of the kinetic parameters of the process are required. The paper presents the determined values of activation energies and optimum temperatures for porcine pancreas lipase. The parameters were estimated based on the literature of the activity curves vs. temperature for hydrolysis of olive oil by lipase. It was noticed that concentration of gum arabic added as an emulsifier during lipase activity measurements influences on the obtained values of determined parameters. A mathematical model describing the effect of temperature on porcine pancreas lipase activity was used. Based on the comparison analysis, the optimum temperature Topt were obtained in the range from 313.30 ±0.56 to 319.62 ±0.96 K, activation energies Ea were from 51 ±10 to 82.6 ±9.9 kJ/mol, and values of deactivation energies Ed were in the range from 122.7 ±4.0 to 150.9 ±5.8 kJ/mol.

5

A Promising Way to Dispose of Fatty Waste by Hydrolysis and Study of the Conditions for Immobilization of Rhizopus Japonicus Lipase on Carriers

Skliar Viktoriia, Krusir Galina, Shunko Hanna, Zakharchuk Valentyna, Malovanyy Myroslav

Journal of Ecological Engineering

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2020

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Vol. 21, nr 2

201--208

EN

The hydrogenation process in oil and fat production is accompanied by the formation of a large amount of waste, the majority of which includes spent catalysts and spent sorbents. The bioconversion of lipids through the use of immobilized enzyme preparations expands the possibilities and is one of the most powerful resource potentials of environmental biotechnology. The adsorption methods are most effective, which is due to the ease of the binding process, the low cost of the carrier and the absence of toxic substances. Immobilization of adsorption provides a large surface area, which is important for the lipolytic enzymes performing catalysis at the interface. In most cases, adsorption slightly reduces the activity of lipases and, which is extremely important, does not affect their specificity. It was shown that the use of activated carbon with a grain size of 2.0–2.8 as a carrier for immobilization of lipase, leads to maximum preservation of the initial lipolytic activity. The weight ratio of carrier/ enzyme, optimal in terms of preservation of lipolytic activity, was 1 g of biopolymer carrier per 500 mg of lipase (1: 0.5) with preservation of 36.33% of the initial activity of the native enzyme. From the obtained experimental data, it follows that the rational conditions for the immobilization of Rhizopus japonicus is GM 1.5, temperature 25°С, duration of immobilization 15 minutes, the size of particles of activated carbon as a matrix is 2.0–2.8 mm. The lipolytic activity of the enzyme immobilized under these conditions is preserved by more than 30% compared with the native one, which is a high indicator of the preservation of activity.

6

Polycarbonate biodegradation by newly isolated Bacillus strains

Arefian Mojgan, Tahmourespour Arezoo, Zia Mohammadali

Archives of Environmental Protection

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2020

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Vol. 46, no. 1

14--20

EN

As polycarbonate is frequently used in many products, its accumulation in landfills is absolutely harmful to the environment. The aims of this study were the screening and isolation of polycarbonate-degrading bacteria (PDB) and the assessment of their ability in the degradation of polycarbonate (PC) polymers. Nine-month buried- -PC films were used for PDB isolation and identification. The biodegradation ability of the isolates was determined by growth curve, clear zone formation, lipase and amylase production, AFM and FTIR. Bacillus cereus and Bacillus megaterium were identified and considered as PDB. The degradation ability of B. megaterium was significantly higher than that of B. cereus. Both were lipase and amylase positive. AFM and FTIR results showed the initiation of bacterial attachment. The PC biodegradation ability of isolates can be very efficient. Finding such efficient isolates (which was less studied before) will promise a decrease in plastic contamination in the future.

7

Kinetic properties of Lipase obtained from Pseudomonas aeruginosa isolated from crude oil contaminated soil

Femi-Ola Titilayo Olufunke, Orjiakor Paul Ikechukwu, Enerijiofi Kingsley Erhons, Oke Iyanuoluwa Omolade, Fatoyinbo Adebayo Adeola

Zeszyty Naukowe Akademii Morskiej w Szczecinie

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2019

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nr 59 (131)

154--161

EN

Soil contaminated with crude oil has negatively affected some of the communities in Ekiti State region in Nigeria. There is an increased interest in microbial lipases because of their enormous potential in industrial and biotechnological applications. This study investigated the characteristics of partially-purified lipase from Pseudomonas aeruginosa isolated from oil-contaminated soil in Ado-Ekiti, Ekiti State. The lipase was purified by gel-filtration, having a molecular weight of 39.11 kDa, with Km and Vmax values of 12.50 and 28.86, respectively. The enzyme had an optimal pH of 8.0 and exhibited its maximal activity at 50°C, whereas the relatively stable temperature and pH were 40°C and 5.0, respectively. The enzyme activity was enhanced by olive oil, which served as the carbon source. Sodium chloride enhanced lipase activity, while calcium chloride acted as mild inhibitor, and iron chloride acted a strong inhibitor. The lipase from Pseudomonas aeruginosa possessed properties of an industrial enzyme and will be useful for biodegradation and bioremediation studies.

8

Nowe trendy w regeneracji lipaz ®

Kowalska M., Jagiełło O.

Postępy Techniki Przetwórstwa Spożywczego

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2018

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nr 2

85--89

PL

Możliwość przeprowadzania przez enzymy reakcji biotransformacji, spowodowała wprowadzenie ich jako katalizatorów wielu procesów syntezy, w takich obszarach życia jak: przemysł spożywczy, kosmetyczny, farmaceutyczny czy ogólnie chemiczny. Pomimo szeregu zalet, które są przedstawione w poniższym artykule, ciągle istnieje blokada stosowania lipaz w użyciu powszechnym, a mianowicie wysoka cena. Ze względu na nią lipazy stosowane są tylko dla specjalnych potrzeb i zadań. Aby rozwiązać problem wysokiego kosztu enzymów należy doskonalić metody ich odzysku i regeneracji oraz późniejszego zawrócenia do procesu. Celem artykułu jest przedstawienie możliwych sposobów odzysku, oczyszczenia oraz ponownego użycia zregenerowanego enzymu.

EN

The possibility of biotransformation reactions carried out by the enzymes caused their introduction as catalysts of many synthetic processes in such areas of life as food, cosmetic, pharmaceutical or general chemical industry. Despite of the many advantages that are presented in the following article, there is still a limitation in the use of lipases in a general application. It is a high price. Due to it, lipases are used only for special needs and tasks. To solve the problem of high cost of enzymes, methods for their recovery and regeneration and subsequent return to the process should be improved. The aim of the article is to present the possible ways of recovery, purification and reuse of the regenerated enzyme.

9

Enzymatic synthesis and characterization of polycaprolactone by using immobilized lipase onto a surface-modified renewable carrier

Ulker C., Gokalp N., Guvenilir Y.

Polish Journal of Chemical Technology

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2016

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Vol. 18, nr 3

134--140

EN

In the present study, rice husk ash, which is a renewable and abundant material, was utilized as a carrier for lipase immobilization for the first time. Poly (ε-caprolactone) synthesis was successfully achieved by the new enzymatic catalyst: Candida antarctica lipase B immobilized onto surface-modified rice husk ashes by covalent binding. It was aimed to obtain optimum polymerization conditions at which highest molecular weight was reached and characterize the polymer produced. Moreover, thermal stability and effectiveness of the new biocatalyst in non-aqueous media were also shown with successful polymerization reactions. In addition, by using the new enzyme preparation, ε-caprolactone was able to be polymerized even at 30°C, which was promising for an energy saving process. Consequently, this work provides a new alternative route for poly (ε-caprolactone) synthesis.

10

Enzymatic activity of a novel halotolerant lipase from Haloarcula hispanica 2TK2

Ozgen M., Attar A., Elalmis Y., Birbir M., Yucel M.

Polish Journal of Chemical Technology

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2016

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Vol. 18, nr 2

20--25

EN

A strain of Haloarcula hispanica isolated from Tuzkoy salt mine, Turkey exhibited extracellular lipolytic activity. Important parameters such as carbon sources and salt concentration for lipase production were investigated. Optimal conditions for the enzyme production from Haloarcula hispanica 2TK2 were determined. It was observed that the lipolytic activity of Haloarcula hispanica was stimulated by some of the carbon sources. The high lipase acitivity values were obtained in the presence of 2% (v/v) walnut oil (6.16 U/ml), 1% (v/v) fish oil (5.07 U/ml), 1% (v/v) olive oil (4.52 U/ml) and 1% (w/v) stearic acid (4.88 U/ml) at 4M NaCl concentration. Lipase was partially purified by ammonium sulfate precipitation and ultrafiltration. Optimal temperature and pH values were determined as 45oC and 8.0, respectively. Lipase activity decreased with the increasing salt concentration, but 85% activity of the enzyme was maintained at 5M NaCl concentration. The enzyme preserved 41% of its relative activity at 90oC. The partially purified lipase maintained its activity in the presence of surfactants such as Triton X-100 and SDS. Therefore, the lipase which is an extremozyme may have potential applications especially in detergent industry.

11

Improving the Hydrophobic Properties of Starch-Protein Raw Material by Enzymatic Modification

Wietecha J., Kazimierczak J., Pałys B., Gutowska A.

Fibres & Textiles in Eastern Europe

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2016

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Vol. 24, no. 6 (120)

196--201

EN

In this study, starch-protein raw material was esterified with oleic acid, vinyl laurate as well as rape oil as an acyl donor. Chloroform was used as a reaction medium and immobilized lipase from Candida antarctica as a catalyst. The degree of substitution (DS) of the products was determined by the volumetric method. The effect of the reaction parameters such as the kind of acyl donor or scale of the process on the DS, was studied. The product with the highest DS (in small scale - 0.11) was found in the reaction carried out at 50 °C for 6 h with oleic acid. Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) analyses confirmed the esterification of the starch-protein material. The hydrophobicity of non-esterified material and the final product was evaluated using the sessile drop method according to European Pharmacopeia 8.0. The possibility of processing the product of esterification into pellets to be used for film and fittings production was examined.

PL

Mąka funkcjonalna uzyskana w wyniku kontrolowanej obróbki hydrotermicznej klasycznej mąki została wykorzystana do pozyskania nowych biopolimerów. Głównym składnikiem tego produktu jest skrobia, ale zawiera on także inne substancje, w tym białka. W pracy przedstawiono badania dotyczące enzymatycznej modyfikacji skrobiowej frakcji surowca skrobiowo-białkowego z zastosowaniem kwasu oleinowego, oleju rzepakowego i laurynianu winylu jako donorów grup acylowych. Jako środowisko reakcji zastosowano chloroform, zaś jako katalizatora użyto immobilizowaną lipazę Candida antarctica. Stopień podstawienia produktu (DS) określano metodą wolumetryczną. Badano wpływ na stopień podstawienia takich parametrów reakcji jak rodzaj donora czy skala procesu. Produkt o najwyższym DS uzyskano prowadząc reakcję (w małej skali) w 50°C przez 6 h z wykorzystaniem kwasu oleinowego jako drugiego substratu. Spektroskopia w podczerwieni z transformacją Fouriera (FTIR) oraz magnetyczny rezonans jądrowy (NMR) potwierdziły otrzymanie pochodnych estrowych. Hydrofobowość materiału wyjściowego i produktów estryfikowanych oceniano stosując metodę siedzącej kropli zgodną z European Pharmacopeia 8.0. Zbadano możliwość przetwarzania pochodnych estrowych na granulat, z którego wytwarzane mogą być folie i kształtki.

12

Aktywność metaboliczna grzybni trufli letniej Tuber aestivum/Tuber uncinatum Vittad

Jankiewicz U., Russel S., Bagińska E., Hilszczańska D.

Woda-Środowisko-Obszary Wiejskie

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2015

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T. 15, z. 1

59--68

PL

Celem prezentowanych badań było oznaczenie aktywności enzymów wydzielanych do podłoża przez dwie formy trufli letniej: Tuber aestivum i Tuber uncinatum Vittad. W pracy wykazano, że T. aestivum i T. uncinatum uwalniają do podłoża hodowlanego białka enzymatyczne o aktywności: lakazy, proteazy, lipazy oraz celulazy i ksylanazy. Analiza aktywności enzymatycznej w płynnych hodowlach obu form trufli letniej wykazała znaczne różnice biochemiczne pomiędzy nimi. Obserwowano zdecydowanie większą aktywność zewnątrzkomórkowych enzymów u T. aestivum, szczególnie lakazową i peptydazową. Wyniki badań wskazują na różną swoistość substratową lipaz wydzielanych przez te trufle: T. uncinatum syntetyzuje lipazy wykazujące aktywność tylko do octanu p-nitrofenolu, natomiast T. aestivum – także do palmitynianu p-nitrofenolu. W hodowlach obu form trufli wykryto niewielką aktywność celulolityczną i ksylanolityczną. Ksylanazy i celulazy oraz lakazy wydzielane przez grzybnię obu form tych trufli mogą brać udział w procesie zawiązywania symbiozy mykoryzowej.

EN

Truffle have long been appreciated for their culinary value. However, knowledge about their biochemical activity is still insufficient. Therefore, the aim of this study was to preliminarily assess the enzymatic activity of two forms of summer truffle (Tuber aestivum Vittad.). The results showed that studied fungi of the genus truffle (Tuber spp.) – T. aestivum and T. uncinatum secrete extracellular enzymatic proteins with activities of: laccase, protease lipase, cellulase and xylanase. The high activity of the enzyme was observed between 10th and 20th day of truffle cultivation in liquid culture. Higher activity of all tested enzymes was detected in the culture of T. aestivum. Significant differences observed in the level and kind of enzymatic activity might indicate different metabolic activity of studied forms of summer truffle.

13

Enancjoselektywna enzymatyczna desymetryzacja katalizowana lipazami. Część 1, Związki prochiralne

Kołodziejska R., Karczmarska-Wódzka A., Tafelska-Kaczmarek A., Studzińska R., Dramiński M.

Wiadomości Chemiczne

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2013

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[Z] 67, 7-8

751--772

EN

In the enzymatic asymmetric synthesis, the enzyme allows the desymmetrization of achiral compounds resulting in chiral compounds of high optical purity. Therefore, this type of biotransformation is known as enantioselective enzymatic desymmetrization (EED) [1–11]. This method is related to the generation of an asymmetry (loss of symmetry elements) in prochiral molecules (most often an sp3 or sp2 hybridized carbon atom), in meso synthones, and centrosymmetric compounds. An achiral center of the tetrahedral system is defined as a prochiral one if it becomes chiral as a result of one of the two substituents replacement which, when separated from the particles, are indistinguishable (Scheme 1, 2) [1–4, 9, 12]. Asymmetric synthesis is enantioselective when one of the enantiotopic groups or faces of an optically inactive compound is biotransformed faster than the other (Scheme 3–5) [1, 10, 11, 13–15]. Lipases are enzymes of highest importance in stereoselective organic synthesis, mainly due to their exceptionally broad substrate tolerance, stability, activity in unphysiological systems, and relatively low price [9, 14]. The mechanism of enzymatic hydrolysis catalysed by hydrolases is similar to that observed in the chemical hydrolysis with the use of base. The selectivity of enzymatic catalysis depends on the substrate orientation in the enzyme active site (Scheme 6, 7) [25–29]. Lipases were successfully used for the desymmetrization of different prochiral diesters, alcohols and amines. Most lipases preferentially convert the same prochiral groups in the above mentioned types of reaction. This allows the preparation of the both enantiomers of the product in high chemical and optical yield (Scheme 9–13) [9, 13, 32–56].

14

Enancjoselektywna enzymatyczna desymetryzacja katalizowana lipazami. Część II, Optymalizacja warunków reakcji. Związki mezo

Karczmarska-Wódzka A., Kołodziejska R., Tafelska-Kaczmarek A., Przybyła T., Dramiński M.

Wiadomości Chemiczne

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2013

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[Z] 67, 9-10

819--841

EN

In the enzymatic asymmetric synthesis, the enzyme allows the desymmetrization of achiral compounds resulting in chiral compounds of high optical purity. Meso compounds (bearing a plane of symmetry) are very important group of compounds used in EEDs (Scheme 1) [1–4]. Similarly to prochiral compounds, selective acylation or hydrolysis of meso substrates leads to optically active products. Most lipases preferentially convert the same enantiomers in the above mentioned types of reaction. This allows the preparation of the both enantiomers of the product in high chemical and optical yield (Scheme 3–20) [35–58]. An effective enzymatic catalysis should be performed under conditions optimal for a biocatalyst performance. Hence, it is essential to select an appropriate reaction medium, the pH, and temperature [6–34]. Optimization of the reaction conditions in terms of an appropriate solvent selection is effective and most frequently the simplest way to modify the enzyme selectivity. One of the most important criteria for the solvent selection is its nature [25]. The enzyme selectivity is conditioned by its conformational rigidity, which increases in more hydrophobic medium (typical hydrophobic solvents, scCO2). A hydrophobic solvent decreases biocatalyst lability, which does not allow the connection between the structurally mismatched substrate and the active side of an enzyme [10, 26–31]. Ionic liquids are a separate group of solvents which, despite their high hydrophobicity (logP << 0) and polarity, can constitute an ideal medium for the biotransformation reactions [18–23].

15

Free fatty acids and a high initial amount of biomass in the medium increase the synthesis of mannosylerythritol lipids by Pseudozyma antarctica

Dzięgielewska E., Adamczak M.

Environmental Biotechnology

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2013

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Vol. 9, No. 1

14--18

EN

It was shown that the addition of lipase to a YPG cultivation medium containing 5% (v/v) of rapeseed oil increased the yield of mannosylerythritol lipids synthesized by P. antarctica from 12.69 to 26.97g·L-1 compared to the control culture. As a renewable resource of free fatty acids for P. antarctica cultivation, post-refining fatty acids (Post-FFA) were used and after 192h a 85.43g·L-1 of biosurfactant was obtained. The experiments indicated that the biosurfactant synthesis could depend on carbon source availability and biomass concentration in the cultivation medium. The supplementation of the medium after 8 days of cultivation (fed-batch culture), with glucose to 2% (w/v) and Post-FFA to 20% (v/v), did not increase the concentration of the biosurfactant in the medium but did increase the total amount of the product from about 170 to 232g. By increasing the initial concentration of the biomass to 500g·L-1, the concentration of biosurfactant was increased to 120.50g·L-1 after 168h.

16

Synteza enzymatyczna multiblokowego kopolimeru poli(bursztynianu butylenu-co-glikolu etylenowego) (PBS-EG) katalizowana lipazą B ze szczepu Candida antarctica

Gradzik B., El Fray M.

Engineering of Biomaterials

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2013

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Vol. 16, no. 121

42--48

PL

W pracy przedstawiono badania nad syntezą segmentowego kopoli(estro-eteru) - poli(bursztynianu butylenu-co-glikolu etylenowego) (PBS-EG) z użyciem lipazy B, pochodzącej ze szczepu Candida antarctica jako katalizatora. Polimeryzację przeprowadzono w roztworach eteru difenylowego z udziałem bursztynianu dietylu i 1,4-butanodiolu oraz poli(glikolu etylenowego) (PEG), wprowadzanego na różnych etapach reakcji, w temperaturze 80oC w warunkach zmiennego ciśnienia. Oceniono wpływ ciśnienia oraz sposobu wprowadzania PEGu na budowę chemiczną i właściwości termiczne otrzymanych kopoli(estro-eterów). Budowa chemiczna zsyntezowanych kopolimerów została oceniona na podstawie spektroskopii magnetycznego rezonansu jądrowego (1H NMR) oraz spektroskopii w podczerwieni (IR). Właściwości termiczne zbadano metodą różnicowej kalorymetrii skaningowej (DSC). Wykazano, że zastosowanie enzymu jako katalizatora prowadzi do otrzymania kopolimeru segmentowego, jednak reakcje przebiegają z dosyć niskimi wydajnościami oraz powstałe kopolimery wykazują małą wartość masy molowej. Stwierdzono również, że na większą wydajność reakcji oraz wzrost masy molowej wpływa jej prowadzenie w warunkach nadciśnienia niż podciśnienia.

EN

The paper presents studies on the synthesis of segmented copoly(ester-ether) - a poly(butylene succinate-co-ethylene glycol) (PBS-EG) using as a catalyst - lipase B derived from Candida antarctica strain. The polymerization was performed in the solutions of diphenyl ether, involving diethyl succinate and 1,4-butanediol and poly(ethylene glycol) (PEG) introduced at different stages of the reaction, at 8CPC under variable pressure. The influence of variable pressure and methods of introducing PEG monomer on the chemical structure and thermal properties of resulting copoly(ester-ether) was examined. The chemical structure of synthesized copolyesters was determined by nuclear magnetic resonance spectroscopy (1H NMR) and infrared spectroscopy (IR). The thermal properties were investigated using differential scanning calorimetry (DSC). It was observed that use of enzyme as catalyst allows to obtain a segmented copolymer, however the reactions take place with relatively low yields and molar mass. It was also found that higher yield and molar mass of the reaction was observed at overpressure than at underpressure conditions.

17

Synteza enzymatyczna poli(bursztynianu butylenu) (PBS) katalizowana lipazą B ze szczepu Candida antarctica: nowy, obiecujący materiał dla zastosowań biomedycznych

El Fray M., Gradzik B.

Engineering of Biomaterials

|

2012

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Vol. 15, no. 115

26--31

PL

W pracy przedstawiono polimeryzację enzymatyczną biodegradowalnego poliestru - poli(bursztynianu butylenu) (PBS) przy użyciu lipazy B, pochodzącej ze szczepu Candida antarctica. Polimeryzację przeprowadzono metodą roztworową przy zastosowaniu eteru difenylowego jako medium reakcji. W celu zachowania homogeniczności mieszaniny reakcyjnej użyto estru kwasu bursztynowego, bursztynianu dietylu oraz 1,4-butanodiolu. Polimeryzację prowadzono w ustalonej temperaturze 80°C, zmieniając ciśnienie podczas etapu polikondensacji, odpowiednio 0,3; 1 i 2 mmHg. Oceniono wpływ tego parametru na budowę chemiczną i właściwości fizyko-chemiczne otrzymanego poliestru. Stwierdzono, że niskie ciśnienie zastosowane na etapie polikondensacji powoduje wzrost masy molowej (Mn), zmniejszenie ilości wolnych grup hydroksylowych oraz wzrost temperatury topnienia finalnego poliestru. Optymalne warunki prowadzenia reakcji zanotowano przy ciśnieniu rzędu 0,3 mmHg, przy którym osiągnięto wysoką wydajność reakcji (37%) i najwyższą wartość masy molowej (ponad 2,5 kDa) zaledwie po 9 h prowadzenia reakcji.

EN

In this work, the enzymatic polymerization of biodegradable polyester - poly(butylene succinate) (PBS) with the use of lipase B, derived from Candida antarctica strain is presented. The polymerization was performed by the solution method with the use of diphenyl ether as a solvent. To avoid the phase separation of monomers diethyl succinate and 1,4-butanediol were applied. The polymerization was carried out at a fixed temperature of 80°C, at variable pressure during polycondensation, namely 0.3, 1, and 2 mmHg. The influence of this parameter on the chemical structure and physico-chemical properties of resulting polyesters were examined. It was observed that low pressure used in the polycondensation facilitated an increase of the molecular weight (Mn), the reduction in -OH groups number and an increase in the melting point of the resulting polyesters. The most effective pressure conditions were found at 0.3 mmHg where relatively high yield of the reaction (37%) and the highest molecular weight (above 2.5 kDa) were found after only 9 hours of the reaction.

18

Substrate inhibition in lipase-catalysed transesterification of mandelic acid with vinyl acetate

Dąbkowska K., Pilarek M., Szewczyk K. W.

Chemical and Process Engineering

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2012

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Vol. 33, nr 4

539--546

EN

Kinetic resolution of (R)- and (S)-mandelic acid by its transesterification with vinyl acetate catalysed by Burholderia cepacia lipase has been studied. The influence of the initial substrate concentration on the kinetics of process has been investigated. A modified ping-pong bi-bi model of enzymatic transesterification of (S)-mandelic acid including substrate inhibition has been developed. The values of kinetic parameters of the model have been estimated. We have shown that the inhibition effect revealed over a certain threshold limit value of the initial concentration of substrate.

19

Enzymatic degradation of polycarbonate urethanes crosslinked with carbohydrates

Wojturska J.

Polish Journal of Applied Chemistry

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2011

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Vol. 55, nr 3-4

141-149

EN

The potential erosive effect of enzymes on polycarbonate urethanes has been evaluated. Polyurethanes were obtained in two-stage polyaddition process which involved diisocyanate (TMDI) and poly(carbonate)diol (Desmophen DC2200) The isocyanate prepolymers were crosslinked with carbohydrates (sucrosc, glucose, mannitol, sorbitol) to improve the ability of the enzyme to degrade polymer. Obtained samples were treated by lipase from Candida antarctica (Novozvm 735). Surface characteristic changes after enzymatic degradation were observed using confocal microscopy. The roughness parameters were determined. Also evaluation the degree of changes of the free surface energy was done. In addition, the thermal analysis of pre-degraded and post-degraded residue was performed.

20

Application of lipase in shaping Al2O3-mullite composites

Szafran M., Bednarek P., Piwowarski P.

Kompozyty

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2011

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R. 11, nr 1

90-94

EN

The paper presents the method of Direct Coagulation Casting (DCC) which is a recently developed method of near-netshaping of ceramic components at low costs. The process relies on electrostatic stabilized ceramic suspensions and their destabilization owing to time delayed in situ reactions. In the method, the enzyme-catalized reaction is used to shift the pH of the ceramic suspension to the isoelectric point, which causes coagulation of the slurry. The aim of this work is the research on shaping alumina-mullite composites with the application of a lipase-catalyzed decomposition of glycerin triacetate. Zeta potential measurements in relation to pH were performed and the appropriate substrate and enzyme was chosen to conduct controlled coagulation of ceramic slurry. In the DCC method, the optimal composition of ceramic suspension was experimentally chosen. The slip gaining a high concentration of ceramic powders, small amount of organic additives, good flow properties and the shortest time after which the intensive increase of viscosity, was considered as optimal. The paper also presents the results of the viscosity of slurries with different concentrations of dispersant and lipase. The sintering temperature leading to the best density and mechanical strength parameters was found to be 1600°C. The relative densities of DCC sintered samples were higher than 95%. The Vickers hardness and fracture toughness KIC for DCC sintered samples were measured. The main conclusion is that the DCC method, using the lipaze-catalyzed decomposition of glycerin triacetate, can be successfully applied to the formation of complex-shaped alumina-mullite composites. Very good mechanical properties can be achieved due to the low content of binders and other additives.

PL

W ostatnich latach prowadzone są intensywne badania nad zastosowaniem technik formowania elementów ceramicznych opartych na układach koloidalnych. Do jednych z takich metod należy bezpośrednie odlewanie koagulacyjne (Direct Coagulation Casting, DCC), dzięki któremu można formować elementy o skomplikowanej geometrii, stosując ceramiczne masy lejne o wysokim stężeniu fazy stałej i małej ilości dodatków organicznych. Metoda DCC jest alternatywą dla formowania metodą wtrysku, wymagającą stosowania wysokich ciśnień oraz znacznej ilości dodatków organicznych oraz dla tradycyjnego formowania przez odlewanie do porowatych form gipsowych. W artykule przedstawiono wyniki badań nad formowaniem kształtek z kompozytów tlenek glinu-mullit z wykorzystaniem reakcji enzymatycznego rozkładu trójoctanu glicerolu lipazą. Wykonano pomiary potencjału zeta w funkcji pH dla czystych proszków tlenku glinu i mullitu oraz dla kompozytu wraz z pozostałymi składnikami ceramicznej masy lejnej. Na podstawie otrzymanych wyników dobrano substrat oraz enzym, pozwalające na przeprowadzenie kontrolowanej koagulacji masy lejnej. Na drodze eksperymentalnej dobrano optymalny skład masy lejnej tak, aby lepkość układu była stosunkowo niska, a czas koagulacji masy relatywnie krotki. Przedstawiono wyniki pomiarów lepkości ceramicznych mas lejnych w funkcji czasu dla rożnych ilości upłynniacza i lipazy w masie. Otrzymane elementy spieczono w temperaturze 1600°C. Uzyskano spieki o gęstości względnej powyżej 95% oraz o wysokich wartościach twardości mierzonej metodą Vickersa i odporności na kruche pękanie KIC mierzonej metodą pomiaru długości pęknięć wykonanych wgłębnikiem diamentowym Vickersa.