bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of new yeast lipases
Authors: Hou Ching T. 
Published: June 2007

AbstractPreviously, we used a simple, sensitive agar plate method to screen lipase activity from 1229 selected cultures, including 508 bacteria, 479 yeasts, 230 actinomycetes and 12 fungi, that covered many genera and species. About 25% of the cultures tested were lipase‐positive. We also expanded our screening method to focus specifically on the pH dependence and thermostability of these lipase activities. In this report, we have characterized 25 yeast lipases, obtained from our screening program, on the basis of their positional specificity against triglycerides. Lipase was produced by growing cultures on nutrient medium in the presence of vegetable oil at 25°C for 4 d. Of the 25 new yeast lipases analyzed, 19 showed 1,3‐positional specificity and 6 showed random specificity. No 2‐positional specific lipases were found. Among those cultures with highest lipase activity are: Candida silvicola NRRL YB‐2846 (random); Candida sp. 55 (random); Candida sp. 125 (random); Pichia americana NRRL Y‐2156 (1,3‐specific); P. muscicola NRRL Y‐7005 (random); P. petersanii NRRL YB‐3808 (1,3‐specific); and Yarrowia lipolytica NRRL YB‐423 (random). Characterization of Candida sp. strain 55 lipase on its substrate preference showed that this enzyme hydrolyzed soybean oil triglyceride species LLLn, LLL, LLO, and LLP more readily than LOO, LOP, OOO, LOS, and POO, where L=linoleic, Ln=linolenic, O=oleic, P=palmitic, and S=stearin.
Additive effects of acyl‐binding site mutations on the fatty acid selectivity of Rhizopus delemar lipase
Authors: Klein Robert R. , King Gregory , Moreau Robert A. , McNeill Gerald P. , Villeneuve Pierre , Haas Michael J. 
Published: June 2007

AbstractThe fatty acid specificity and pH dependence of triacylglycerol hydrolysis by the Rhizopus delemar lipase acylbinding site mutant Val206Thr+Phe95Asp (Val, valine; Thr, threonine; Phe, phenylalanine; Asp, aspartic acid) were characterized. The activity of the double mutant prolipase was reduced by as much as 10‐fold, compared to the wild‐type prolipase. However, the fatty acid specificity profile of the enzyme was markedly sharpened and was dependent on the pH of the substrate emulsion. At neutral pH, strong preference (10‐fold or greater) for hydrolysis of triacylglycerols of medium‐chainlength fatty acids (C8:0 to C14:0) was displayed by the variant prolipase, with no hydrolysis of triacylglycerols of short‐chain fatty acids (C4:0 to C6:0) and little activity manifested toward fatty acids with 16 or more carbons. At acidic pH values, the fatty acid selectivity profile of the double mutant prolipase expanded to include short‐chain triacylglycerols (C4:0, C6:0). When assayed against a triacylglycerol mixture of tributyrin, tricaprylin and triolein, the Val206Thr+Phe95Asp prolipase displayed a high selectivity for caprylic acid and released this fatty acid at least 25‐fold more efficiently than the others present in the substrate mixture. When presented a mixture of nine fatty acid methyl esters, the wild‐type prolipase showed a broad substrate specificity profile, hydrolyzing the various methyl esters to a similar extent. Contrastingly, the double mutant prolipase displayed a narrowed substrate specificity profile, hydrolyzing caprylic methyl ester at nearly wild‐type levels, while its activity against the other methyl esters examined was 2.5‐ to 5‐fold lower then that observed for the wild‐type enzyme.
Enzymatic synthesis of position‐specific low‐calorie structured lipids
Authors: Akoh Casimir C. , Yee Lisa N. 
Published: June 2007

AbstractAn immobilized sn‐1,3‐specific lipase from Rhizomucor miehei (IM 60) was used to catalyze the interesterification of tristearin (C18:0) and tricaprin (C10:0) to produce low‐calorie structured lipids (SL). Acceptable product yields were obtained from a 1:1 mole ratio of both triacylglycerols with 10% (w/w of reactants) of IM 60 in 3 mL hexane. The SL molecular species, based on total carbon number, were 44.2% C41 and 40.5% C49, with 3.8 and 11.5% unreacted tristearin C57 and tricaprin C27, respectively, remaining in the product mixture. The best yield of C41 species (44.3%) was obtained with zero added water. Tricaprylin (C8:0) was also successfully interesterified with tristearin in good yields at 1:1 mole ratio. Products were analyzed by reverse‐phase high‐performance liquid chromatography with an evaporative light‐scattering detector. Reaction parameters, such as substrate mole ratio, enzyme load, time course, added water, reaction media, and enzyme reuse, were also investigated. Hydrolysis by pancreatic lipase revealed the specific fatty acids present at the sn‐1,3 positions of SL.
Water activity‐adjusted enzymatic partial hydrolysis of phospholipids to concentrate polyunsaturated fatty acids
Authors: Ono Masayo , Hosokawa Masashi , Inoue Yoshikazu , Takahashi Koretaro 
Published: June 2007

AbstractSelective partial hydrolyses of egg yolk phospholipid and squid skin phospholipid were carried out. By keeping the water activity (aw) of Lipozyme IM at an intermediate level, it was easy to concentrate docosahexaenoic acid (DHA). It was also possible to concentrate both DHA and arachidonic acid (AA) simultaneously to a certain level under this aw range. However, it was impossible to concentrate AA alone when DHA was present. Though there is a limitation in concentrating AA exclusively, the proposed aw‐adjusted hydrolytic reaction is a promising way for preparing phospholipids rich in DHA.
Preparation of highly purified concentrates of eicosapentaenoic acid and docosahexaenoic acid
Authors: Breivik Harald , Haraldsson Gudmundur G. , Kristinsson Björn 
Published: June 2007

AbstractBecause of the complexity of marine lipids, polyunsaturated fatty acid (PUFA) derivatives in highly purified form are not easily prepared by any single fractionation technique. The products are usually prepared as the ethyl esters by esterification of the body oil of fat fish species and subsequent physicochemical purification processes, including short‐path distillation, urea fractionation, and preparative chromatography. Lipase‐catalyzed transesterification has been shown to be an excellent alternative to traditional esterification and short‐path distillation for concentrating the combined PUFA‐content in fish oils. At room temperature in the presence of Pseudomonas sp. lipase and a stoichiometric amount of ethanol without any solvent, efficient transesterification of fish oil was obtained. At 52% conversion, a concentrate of 46% eicosapentaenoic acid (EPA) plus docosahexaenoic acid (DHA) was obtained in excellent recovery as a mixture of mono‐, di‐, and triacylglycerols. The latter can be easily separated from the saturated and monounsaturated ethyl esters and converted into ethyl esters either by conventional chemical means or enzymatically by immobilized Candida antarctica lipase. Urea‐fractionation of such an intermediary product can give an EPA+DHA content of approximately 85%.
Production of high yields of docosahexaenoic acid by Schizochytrium sp. strain SR21
Authors: Yaguchi T. , Tanaka S. , Yokochi T. , Nakahara T. , Higashihara T. 
Published: June 2007

AbstractThe culture conditions for high‐yield production of docosahexaenoic acid (DHA) by Schizochytrium sp. strain SR21 were investigated in a fermenter. With increasing carbon (glucose) and nitrogen (corn steep liquor and ammonium sulfate) sources (up to 12% glucose) in the medium, DHA productivity increased without a decrease in growth rate, i.e., 2.0, 2.7, and 3.3 g DHA/L/d with 6, 10, and 12% glucose, respectively. Eventually, 48.1 g dry cells/L and 13.3 g DHA/L were produced in 4 d with 12% glucose. DHA productivity was decreased with 15% glucose, i.e., 3.1 g/L/d. With 12% glucose, the lipid content was 77.5% of dry cells, and DHA content was 35.6% of total fatty acids. The lipid was composed of about 95% neutral lipid and 5% polar lipid. In polar lipids, the contents of phosphatidylcholine (PC), phosphatidylethanolamine, and phosphatidylinositol were 74, 11, and 5%, respectively. The PC profile was simple, 70% of PC molecules were 1‐palmitoyl‐2‐DHA‐PC and 1.2‐di‐DHA‐PC. These results indicate that Schizochytrium sp. strain 21 is an excellent source for microbial DHA production, including not only the acid form of DHA but also 2‐DHA‐PC.
Industrial high‐performance liquid chromatography purification of docosahexaenoic acid ethyl ester and docosapentaenoic acid ethyl ester from single‐cell oil
Authors: Yamamura R. , Shimomura Y. 
Published: June 2007

AbstractThe use of polyunsaturated fatty acids (PUFA) as medicine or in functional diets requires high purity. An industrial purification method for PUFA from Schizochytrium sp. SR21 oil was investigated. This oil contains fewer unwanted components than fish oils. Docosahexaenoic acid and docosapentaenoic acid ethyl esters (DHA‐E and DPA‐E) were prepared by treatment of this oil with ethanol and 1 N potassium hydroxide in hexane. DHA‐E and DPA‐E were purified by an industrial high‐performance liquid chromatography (HPLC) plant. The separation plant consists of two columns (400 mm i.d., 1,000 mml) with temperature‐controlled water jackets and double‐plunger (four heads) injection and eluent pumps. This plant was computer‐controlled and equipped with an explosion‐prevention system. The packed material was octadecylsilica (reverse‐phase ODS), and the eluent was methyl alcohol/water (98:2). DHA‐E and DPA‐E from single‐cell oil were highly purified by this industrial HPLC method in a one‐step process. The DHA‐E and DPA‐E obtained were better than 99% purity.
Carica papaya latex‐catalyzed synthesis of structured triacylglycerols
Authors: Foglia T. A. , Villeneuve P. 
Published: June 2007

AbstractOne impediment to the industrial use of enzymes in fat and oil transformations is the higher cost often associated with an enzymatic process compared with the corresponding chemical process. Processes that utilize plant enzymes, however, may have advantages because of their lower cost and ready availability. One example of such a plant‐derived enzyme is Carica papaya latex (CPL), the principal source of the protease papain. Recently, it has been shown that this latex also catalyzes the lipolysis of triacylglycerols and that this latex lipase has a selectivity for short‐chain acyl groups as well as a 1,3‐glycerol selectivity. These selectivities can be used in the synthesis of structured triacylglycerols. In this paper we describe the utility of CPL in lipase‐catalyzed reactions, specifically the synthesis of low‐calorie triacylglycerol analogs.
Improvement of palm oil through breeding and biotechnology
Authors: Jalani B. S. , Cheah S. C. , Rajanaidu N. , Darus A. 
Published: June 2007

AbstractThe oil palm Elaeis guineensis is the highest oil‐yielding crop and has the potential to become the major supplier of both edible oil and renewable industrial feedstock. The oil yield from wild groves is presently less than 0.5 t/ha/y. However, through breeding and selection, the oil yield of commercial plantations could reach as much as 8 t/ha/y. New planting materials also have the capability of better oil yields with high iodine value (IV), slow height increment, and larger kernels. The oil also contains considerable amounts of carotenoids (500–700 ppm), vitamin E (600–1000 ppm), and sterols (250–620 ppm). The oil yield of another oil palm species, E. oleifera, is approximately 0.5 t/ha/y with high contents of carotenoids (700–1500 ppm), vitamin E (700–1500 ppm), and sterols (3500–4000 ppm). The above traits could be improved through breeding and biotechnology. Biotechnological efforts at the Palm Oil Institute of Malaysia are directed toward the production of oil with high IV and high monounsaturated fatty acids for edible purposes and industrial uses. Isolation and manipulation of the genes involved in the biosynthesis of fatty acids are the main focus. The aim is to increase the efficiency of conversion of palmitate (C16:0) to oleate (C18:1). Levels of palmitate and oleate are controlled by the enzymes acyl‐acyl carrier protein (ACP) thioesterase and β‐keto acyl ACP synthase II. The chain termination reactions of C16:0 and C18:1 are independent, thus paving the way for the possibility of reducing palmitate levels by switching off the palmitoyl ACP thioesterase gene.
Purification of γ‐linolenic acid from borage oil by a two‐step enzymatic method
Authors: Shimada Yuji , Sugihara Akio , Shibahiraki Masahiro , Fujita Hiroyuki , Nakano Hirofumi , Nagao Toshihiro , Terai Tadamasa , Tominaga Yoshio 
Published: June 2007

Abstractγ‐Linolenic acid (GLA) was purified from borage oil by a two‐step enzymatic method. The first step involved hydrolysis of borage oil (GLA content, 22.2 wt%) with lipase, Pseudomonas sp. enzyme (LIPOSAM). A mixture of 3 g borage oil, 2 g water, and 5000 units (U) LIPOSAM was incubated at 35°C with stirring at 500 rpm. The reaction was 91.5% complete after 24 h. The resulting free fatty acids (FFA) were extracted from the reaction mixture with n‐hexane (GLA content, 22.5 wt%; recovery of GLA, 92.7%). The second step involved selective esterification of borage‐FFA with lauryl alcohol by using Rhizopus delemar lipase. A mixture containing 4 g borage‐FFA/lauryl alcohol (1:2, mol/mol), 1 g water, and 1000 U lipase was incubated at 30°C for 20 h with stirring at 500 rpm. Under these conditions, 74.4% of borage‐FFA was esterified, and the GLA content in the FFA fraction was enriched from 22.5 to 70.2 wt% with a recovery of 75.1% of the initial content. To further elevate the GLA content, unesterified fatty acids were extracted, and esterified again in the same manner. By this repeated esterification, GLA was purified to 93.7 wt% with a recovery of 67.5% of its initial content.
Synthesis of (Z)‐3‐hexen‐1‐yl butyrate in hexane and solvent‐free medium using Mucor miehei and Candida antarctica lipases
Authors: Bourg‐Garros S. , Razafindramboa N. , Pavia A. A. 
Published: June 2007

Abstract(Z)‐3‐Hexen‐1‐yl butyrate is an important flavor and fragrance compound as it represents the model of a natural herbaceous (green) note. Two immobilized lipases from Mucor miehei (Lipozym IM) and from Candida antarctica (Novozym 435) were investigated for their use in the synthesis of (Z)‐3‐hexen‐1‐yl butyrate by direct esterification in n‐hexane. To determine optimal conditions for esterification, we examined the following parameters: temperature, amount of lipase, acid/alcohol ratio, and absence of solvent. In n‐hexane, bioconversion yields reached 95 (after 4 h) and 92% (after 6 h) for, respectively, Lipozym IM [17 (w/w reactants)] and Novozym 435 [2% (w/w reactants)]. In the absence of solvent, at 60°C, Novozym 435‐catalyzed esterification afforded the title compound in 80% yield. Up to 250 g (in hexane) and 160 g (without solvent) of ester were easily prepared, in a single operation, at a laboratory scale, in few hours, using 2% (w/w reactants) lipase.
Synthesis of cocoa butter equivalent by lipase‐catalyzed interesterification in supercritical carbon dioxide
Authors: Liu Kuan‐Ju , Cheng Hong‐Ming , Chang Rey‐Chang , Shaw Jei‐Fu 
Published: June 2007

AbstractWith supercritical carbon dixoide as a reaction medium, the syntheses of cocoa butter equivalent by interesterification with various lipases were investigated. The study showed that among those five lipases tested, lipase IM‐20 from Mucor miehei was the most effective and specific in synthesizing this cocoa butter equivalent product by interesterification. The yields of cocoa butter equivalent are affected by pressure, substrate oil composition, solubility and co‐solvent. The best reaction conditions were: reaction pressure at 1500 psi, triglyceride with high content of POP (P, palmitate; O, oleate) and POO, reaction medium with 5.0% water, and reaction temperature at 50°C. The major component of cocoa butter, POS (S, stearate), can be increased by 6.0% by adding a small amount of carbon dioxide. The yield and melting point of the purified cocoa butter equivalent are 53.0% and 34.3°C, respectively.
Lipase‐catalyzed alcoholysis with supercritical carbon dioxide extraction 1: Influence of flow rate
Authors: Gunnlaugsdottir Helga , Sivik Björn 
Published: June 2007

AbstractA combined process of lipase (E.C. 3.1.1.3) catalysis and extraction of product with supercritical carbon dioxide was studied. The effect of different flow rates of the extraction fluid on the selective removal of the ethyl esters (EE) synthesized in a lipase‐catalyzed alcoholysis of cod liver oil with ethanol was investigated. The faster the flow rate, the faster the extraction rate and the higher the recovery of EE. For example, after a 270‐min extraction, the total recovery of EE was 1520 mg for a flow rate of 0.3 liter carbon dioxide at atmospheric pressure and room temperature/min (NL/min) as compared to 250 mg when 0.015 NL/min was used. The concentration of EE in the carbon dioxide was found to decrease with increasing flow rate, which indicates that the rate of diffusion of EE limits their extraction at fast flow rates. A high flow rate was found to result in a more selective extraction of EE, i.e., less amounts of other lipid components present in the reaction mixture were coextracted with the EE. Further, by increasing the flow rate, the equilibrium of the reaction was shifted slightly toward ester synthesis. An increase in the flow rate from 0.015 to 0.075 NL/min resulted in an approximately 10% increase in total conversion (from 73 to 82%), whereas only a negligible increase was obtained when the flow rate was increased further to 0.15 NL/min.
Lipase‐catalyzed alcoholysis with supercritical carbon dioxide extraction 2: Phase behavior
Authors: Gunnlaugsdottir Helga , Karlsson Anders Å. , Sivik Björn 
Published: June 2007

AbstractThe phase behavior of systems containing ethanol plus lipid samples with different lipid compositions plus carbon dioxide was studied visually at 40°C and pressures of 0.01, 9, 15, and 23 MPa by means of a high‐pressure sapphire cell. The systems studied represent the main components present in a lipase‐catalyzed alcoholysis reaction of cod liver oil in supercritical carbon dioxide. Two phases, a vapor and a liquid phase, were observed in all systems studied at supercritical conditions.
Targeting NF‐κB pathway with an IKK2 inhibitor induces inhibition of multiple myeloma cell growth
Authors: Jourdan Michel , Moreaux Jérôme , Vos John De , Hose Dirk , Mahtouk Karène , Abouladze Matthieu , Robert Nicolas , Baudard Marion , Rème Thierry , Romanelli Angela , Goldschmidt Hartmut , Rossi Jean‐François , Dreano Michel , Klein Bernard 
Published: June 2007

SummaryThe pathophysiologic basis for multiple myeloma (MM) has been attributed to the dysregulation of various paracrine or autocrine growth factor loops and to perturbations in several signal transduction pathways including IκB kinase/nuclear factor‐κB (IKK/NF‐κB). The present study aimed at investigating the effect of a pharmaceutical IKK2 inhibitor, the anilinopyrimidine derivative AS602868, on the in vitro growth of 14 human MM cell lines (HMCL) and primary cells from 13 patients. AS602868 induced a clear dose‐dependent inhibition of MM cell growth on both HMCL and primary MM cells, which was the result of a simultaneous induction of apoptosis and inhibition of the cell cycle progression. Combination of AS602868 with suboptimal doses of melphalan or Velcade showed an additive effect in growth inhibition of HMCL. AS602868 also induced apoptosis of primary myeloma cells. Importantly, AS602868 did not alter the survival of other bone marrow mononuclear cells (CD138−) co‐cultured with primary MM (CD138+) cells, except for CD34+ haematopoietic stem cells. The results demonstrate the important role of NF‐κB in maintaining the survival of MM cells and suggest that a pharmacological inhibition of the NF‐κB pathway by the IKK2 inhibitor AS602868 can efficiently kill HMCL and primary myeloma cells and therefore might represent an innovative approach for treating MM patients.
In or out? Methodological considerations for including and excluding findings from a meta‐analysis of predictors of antiretroviral adherence in HIV‐positive women
Authors: Voils Corrine I. , Barroso Julie , Hasselblad Victor , Sandelowski Margarete 
Published: June 2007

Abstract Title. In or out? Methodological considerations for including and excluding findings from a meta–analysis of predictors of antiretroviral adherence in HIV–positive women Aim.  This paper is a discussion detailing the decisions concerning whether to include or exclude findings from a meta‐analysis of report of quantitative studies of antiretroviral adherence in HIV‐positive women.Background.  Publication constraints and the absence of reflexivity as a criterion for validity in, and reporting of, quantitative research preclude detailing the many judgements made in the course of a meta‐analysis. Yet, such an accounting would assist researchers better to address the unique challenges to meta‐analysis presented by the bodies of research they have targeted for review, and to show the subjectivity, albeit disciplined, that characterizes the meta‐analytic process.Data sources.  Data were 29 published and unpublished studies on antiretroviral adherence in HIV‐positive women of any race/ethnicity, class, or nationality living in the United States of America. The studies were retrieved between June 2005 and January 2006 using 40 databases.Review methods.  Findings were included if they met the statistical assumptions of meta‐analysis, including: (1) normal distribution of observations; (2) homogeneity of variances; and (3) independence of observations.Results.  Relevant studies and findings were excluded because of issues related to differences in study design, different operationalizations of dependent and independent variables, multiple cuts from common longitudinal data sets, and presentation of unadjusted and adjusted findings. These reasons led to the exclusion of 73% of unadjusted relationships and 87% of adjusted relationships from our data set, leaving few findings to synthesize.Conclusion.  Decisions made during research synthesis studies may result in more information losses than gains, thereby obliging researchers to find ways to preserve findings that are potentially valuable for practice.