Differential scanning calorimetric studies of aqueous dispersions of phosphatidylcholines containing two polyenoic chains

Keough, K. M. W.; Kariel, N.

doi:10.1016/0005-2736(87)90130-1

Cited by 84 publications

(36 citation statements)

References 20 publications

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“…In semi-synthesizing mixed-chain PE, all chemical and enzymatic reactions were carried out strictly under N 2 to avoid possible lipid oxidation. All lipids were purified by column chromatography on silica gel 60, with which a mixture of CHCl 3 , CH 3 High Resolution DSC Measurements-The lipid samples used for DSC experiments were prepared according to our previously reported protocols (9). Specifically, the lyophilized lipid power was dispersed in cold aqueous buffer solution containing 50 mM NaCl, 0.25 mM diethylenetriaminepentaacetic acid, 5 mM phosphate buffer, pH 7.4, and 0.02 mg/ml NaN 3 .…”

Section: Methodsmentioning

confidence: 99%

“…Nevertheless, the pioneer work of Keough and co-workers (1-3) did provide interesting results showing how variations in the number of cis double bonds in the sn-2 acyl chain of phosphatidylcholine (PC) at certain fixed positions can affect the phase transition temperature (T m ) of the lipid bilayer. Specifically, Keough and associates (1)(2)(3) have shown by DSC that the introduction of a cis double bond into the sn-2 acyl chain of C (20):C(20)PC at carbon 11 from the carbonyl end, or C(11), gives rise to C (20): C(20:1⌬ 11 )PC, which has a considerably lower T m relative to its saturated counterpart. The introduction of a second cis double bond into the sn-2 acyl chain at the methylene-interrupted position toward the methyl end yields C (20):C(20:2⌬ 11,14 )PC with a further reduction in T m .…”

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confidence: 99%

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Effects of Various Numbers and Positions of cisDouble Bonds in the sn-2 Acyl Chain of Phosphatidylethanolamine on the Chain-melting Temperature

Wang

Huo

et al. 1999

Journal of Biological Chemistry

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In an attempt to investigate systematically the effects of various single and multiple cis carbon-carbon double bonds in the sn-2 acyl chains of natural phospholipids on membrane properties, we have de novo synthesized unsaturated C 20 fatty acids comprised of single or multiple methylene-interrupted cis double bonds. Subsequently, 15 molecular species of phosphatidylethanolamine (PE) with sn-1 C 20 -saturated and sn-2 C 20 -unsaturated acyl chains were semi-synthesized by acylation of C 20 -lysophosphatidylcholine with unsaturated C 20 fatty acids followed by phospholipase D-catalyzed base-exchange reaction in the presence of excess ethanolamine. The gel-to-liquid crystalline phase transitions of these 15 mixed-chain PE, in excess H 2 O, were investigated by high resolution differential scanning calorimetry. In addition, the energy-minimized structures of these sn-1 C 20 -saturated/sn-2 C 20 -unsaturated PE were simulated by molecular mechanics calculations. It is shown that the successive introduction of cis double bonds into the sn-2 acyl chain of C(20):C(20)PE can affect the gel-to-liquid crystalline phase transition temperature, T m , of the lipid bilayer in some characteristic ways; moreover, the effect depends critically on the position of cis double bonds in the sn-2 acyl chain. Specifically, we have constructed a novel T m diagram for the 15 species of unsaturated PE, from which the effects of the number and the position of cis double bonds on T m can be examined simultaneously in a simple, direct, and unifying manner. Interestingly, the characteristic T m profiles exhibited by different series of mixed-chain PE with increasing degree of unsaturation can be interpreted in terms of structural changes associated with acyl chain unsaturation.Most naturally occurring diacyl phospholipids in eukaryotic cell membranes are of a mixed acyl chain variety, meaning that the fatty acids esterified at the sn-1 and sn-2 positions of the glycerol backbone are originated primarily in vivo from saturated and unsaturated fatty acyl-CoA, respectively. Since the chemical composition of fatty acids can vary greatly in terms of the acyl chain length, the degree of unsaturation, and the position of cis carbon-carbon double bonds (⌬-bonds), 1 membrane phospholipids are structurally an extremely diverse group of amphipathic molecules. In a given type of cell, membrane phospholipids may amount to several hundreds of distinctive chemical species. Despite the bewildering diversity, the basic motif of most unsaturated fatty acyl chains is surprisingly simple, viz. in the sn-2 acyl chain, the cis carboncarbon double bonds are invariably separated by a three-carbon unit comprised of a methylene group (-CH 2 -) sandwiched by two olefinic carbons. The biochemical significance of this regular methylene-interrupted interval is, however, not clear.Although it has long been known that mixed-chain diacyl phospholipids in aqueous media can uniquely assemble into a two-dimensional sheet-like structure called the lipid bilayer, progress is non...

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Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

Effects of Various Numbers and Positions of cisDouble Bonds in the sn-2 Acyl Chain of Phosphatidylethanolamine on the Chain-melting Temperature

Wang

Huo

et al. 1999

Journal of Biological Chemistry

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“…Lipid extraction from a 15-g sample of lean tissue followed a modified procedure of Bligh and Dyer (1959) as outlined by Williams et al (2008). Approximately 10 mg of extracted lipid was methylated according to the procedure outlined by Keough and Kariel (1987). Fatty acid methyl esters (FAME) were identified by gas chromatography (GC) using an Agilent 6890 Series GC system equipped with an Agilent 7683 injector (Agilent Technologies, Wilmington, DE) using a 100 m )0.25 mm )0.2mm fused silica capillary column (SPÁ2560 Supelco Park, Bellefonte, PA) under the following conditions: injector at 2408C, detector at 2508C, and oven temperature held at 1408C for 5 min, increased at 48C min (1 to 2408C and then held at 2408C for 10 min.…”

Section: Fatty Acid Analysis Of L Dorsi Muscle and Cereal Grainsmentioning

confidence: 99%

Performance and carcass characteristics of steers fed a low acid-detergent lignin hull, high-oil groat oat in growing and finishing diets

Zalinko¹,

Racz²,

Rossnagel³

et al. 2009

Can. J. Anim. Sci.

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. 2009. Performance and carcass characteristics of steers fed a low acid-detergent lignin hull, high-oil groat oat in growing and finishing diets. Can. J. Anim. Sci. 89: 521Á530. Two trials were conducted to evaluate the performance and carcass traits of steers fed a low aciddetergent lignin hull, high-oil groat (LLH-HOG) oat in cattle diets. In trial 1, 400 steers (275.4920.8 kg) were fed one of two diets with barley or LLH-HOG oat at 37.8% of the diet (DM basis). Dry matter intake (DMI) was lower (P00.02) (7.49 vs. 7.72 kg d( (1 , respectively). Ultrasound fat and longissimus dorsi (l. dorsi) area, carcass weight and dressing percentage were lower (PB 0.01) for steers fed the oat diet. Stearic acid content of the l. dorsi of oat-fed cattle was greater (PB0.01) than barley-or corn-fed cattle. The ratio of polyunsaturated to saturated fatty acids in the muscle of oat-and corn-fed cattle was greater (P00.01) than that of barley-fed cattle. Results indicate that the energy value of the LLH-HOG oat is equivalent or superior to that of barley for growing cattle; however, research is required to identify why feed intake of finishing cattle fed this grain source is reduced. Mcal par kg) e´taient supe´rieures pour la ration renfermant de l'avoine. Lors du deuxie`me essai, 240 bouvillons (341,7918,1 kg) ont rec¸u une de trois rations contenant 88,2 % d'orge, de maı¨s ou d'avoine, 5,1 % d'ensilage d'orge et 6,7 % de supple´ment (selon la matie`re se`che). Durant la finition, les bouvillons nourris avec de l'avoine avaient un gain quotidien moyen plus faible (PB0,01) que celui des animaux nourris avec de l'orge ou du maı¨s (1,40, 1,69 et 1,84 kg par jour, respectivement), signe qu'ils inge´raient moins de matie`re se`che (PB0,01) (9,56, 10,84 et 11,56 kg par jour, respectivement). L'e´paisseur du gras et la superficie du l. dorsi mesure´es aux ultrasons, le poids de la carcasse et la proportion de parage e´taient plus faibles (PB0,01) chez les bouvillons nourris d'avoine. La teneur en acide ste´arique du l. dorsi e´tait plus e´leve´e (PB0,01) chez les sujets recevant de l'avoine que chez ceux nourris d'orge ou de maı¨s. Le rapport entre les acides gras polyinsature´s et sature´s dans les muscles des animaux engraisse´s a`l'avoine et au maı¨s e´tait plus e´leve´(P 00,01) que chez les bouvillons nourris d'orge. Ces re´sultats indiquent que l'avoine LLH-HOG a une valeur e´nerge´tique e´quivalente ou supe´rieure a`celle de l'orge pour les bovins en croissance, mais il faudrait entreprendre d'autres recherches afin d'e´tablir pourquoi les animaux consomment moins de cet aliment durant la finition.

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“…The procedure for methylation of fatty acids was based on Keough and Kariel (1987). Following this step, the samples were filtered through a glass filter syringe into GC vials.…”

Section: Fatty Acid Analysismentioning

confidence: 99%

Effect of feeding a processed barley/canola meal pellet on performance and carcass quality of feedlot steers

Williams¹,

Block²,

Christensen³

et al. 2008

Can. J. Anim. Sci.

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. 2008. Effect of feeding a processed barley/canola meal pellet on performance and carcass quality of feedlot steers. Can. J. Anim. Sci. 88: 667Á 676. This study was conducted to evaluate the effects of feeding a processed barley/canola meal pellet on feedlot performance and carcass quality of feedlot steers. Cross-bred steers (N0350) weighing 285922kg were assigned to 1 of 12 pens and fed either pelleted (PB) or rolled (RB) barley as the concentrate. During backgrounding, cattle were fed a diet that contained 41% PB or RB based-concentrate (DM basis), which consisted of 85% barley and 15% canola meal. During finishing the diet contained 86% concentrate (DM basis), which consisted of 94% pelleted or rolled barley and 6% canola meal. Data collection included daily pen feed intake, individual body weights, ultrasound backfat (USBF) and longissimus dorsi (USLD) area measurements. Carcass data included weight, dressing percentage, marbling and liver abscess scores. Carcass fat, lean and bone percentage, fat color, and l. dorsi intramuscular fat content and fatty acid profile were determined on eight-bone rib samples from 20 randomly selected steers from each treatment. Steers fed the PB had similar ADG during backgrounding (1.29 vs. 1.23 kg d (1 ; P B0.01), daily gains were greater for cattle fed RB. As a result, cattle fed PB were on feed for 10 d longer (P00.01) than RB fed cattle. DMI was lower (PB0.01) for cattle fed PB throughout the trial. Feed conversion (kg feed:kg gain) was superior for the group fed the PB during finishing (6.03 vs. 6.21; P00.01) and the total trial (6.27 vs. 6.64; PB0.01). Both diets produced similar carcasses, but inter-muscular fat percentage was higher (P00.03) for the RB group (60.0 vs. 57.4%). Minor differences in fatty acid profile were noted with PB fed steers having higher (PB0.01) levels of C17:0, C18:3n-3 and C20:4n-6. Results from this study indicate that PB can be used effectively in growing programs, however, further research is required to better manage feeding of PB products to avoid DMI reductions most likely due to sub-acute rumen acidosis. Pendant la semifinition, les animaux ont rec¸u une ration contenant 41 % de concentre´PB ou RB (concentration de matie`re se`che) compose´a8 5 % d'orge et a`15 % de tourteau de canola. Pendant la finition, la ration servie contenait 86 % de concentre´(concentration de matie`re se`che) constitue´a`94 % d'agglome´re´s ou de flocons d'orge et de 6 % de tourteau de canola. Parmi les donne´es recueillies, on retrouvait l'ingestion quotidienne d'aliments par enclos, le poids corporel de chaque sujet ainsi que l'e´paisseur du gras dorsal et la superficie du l. dorsi mesure´es aux ultrasons. Les donne´es sur la carcasse incluaient le poids, le rendement, le marbre´et le nombre d'abce`s au foie. Les auteurs ont mesure´la proportion de matie`re grasse, de viande maigre et d'os de la carcasse, la couleur des tissus adipeux et la teneur en matie`re grasse intramusculaire du l. dorsi. Ils ont aussi e´tabli le profil des acides gras sur des e´chanti...

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Differential scanning calorimetric studies of aqueous dispersions of phosphatidylcholines containing two polyenoic chains

Cited by 84 publications

References 20 publications

Effects of Various Numbers and Positions of cisDouble Bonds in the sn-2 Acyl Chain of Phosphatidylethanolamine on the Chain-melting Temperature

Effects of Various Numbers and Positions of cisDouble Bonds in the sn-2 Acyl Chain of Phosphatidylethanolamine on the Chain-melting Temperature

Performance and carcass characteristics of steers fed a low acid-detergent lignin hull, high-oil groat oat in growing and finishing diets

Effect of feeding a processed barley/canola meal pellet on performance and carcass quality of feedlot steers

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