蛋黄磷脂的提纯

利用蛋白质不溶或微溶于某些溶剂的特点,用混合溶剂萃取粗蛋黄磷脂制备精蛋黄磷脂的工艺,该工艺易于实现工业化生产,磷脂纯度可达98%以上。     

The emulsifying properties of egg yolk phosphatidylcholine

The effects of lipid concentration and w/w ratios on the formation of emulsions by some combinations of phosphatidylcholine, cholesterol oleate, cholesterol and triglyceride were studied, with the following results. Phosphatidylcholine emulsified cholesterol oleate and triglyceride, the degree of dispersion and emulsion stability increasing with phosphatidylcholine concentration. Cholesterol reduced the degree of dispersion of phosphatidylcholine-triglyceride emulsions but enhanced the emulsion stability. Triglyceride disrupted the colloidal phase of phosphatidylcholine and cholesterol in high concentrations and did so more effectively when the proportion of cholesterol to phosphatidylcholine was high.     

Selective extraction of phospholipids from egg yolk

Solubility differences of phospholipids and tri-glycerides in methanol have been used with advantage for the selective quantitative extraction of phospho-lipids, almost free of triglycerides, from egg yolk. Cholesterol, a comparatively minor component of egg yolk lipids, is easily removed from the methanolic solution of phospholipids by low temperature crystal-lization (5 C), if required.     

Molecular species of phosphatidyl ethanolamine from egg yolk

Phosphatidyl ethanolamine was isolated from total egg yolk lipids by preparative thin layer chromatography (TLC). The purified phosphatide contained 3% of the alkoxy derivative. It was degraded to diglycerides in the presence of purified sphingomyelin by phospholipase C fromClostridium welchii. The diglycerides were acetylated and resolved on the basis of unsaturation by argentation TLC. The fatty acid composition of the original phosphatidyl ethanolamine and the derived acetates was determined by gas chromatography, as was the molecular weight distribution of the diglyceride acetates. The placement of the fatty acids in the parent phosphatide was deduced by hydrolysis with phospholipase A fromCrotalus atrox, and in the acetates with pancreatic lipase. Some 33 major species of phosphatidyl ethanolamine were identified and compared to those for egg yolk lecithins. Presented in part at the Canadian Federation of Biological Societies Meeting, Kingston, June 1968.     

Stereospecific analysis of triglycerides

Stereospecific analysis determines how the fatty acids of triglycerides are distributed over the three different positions of the glycerol. The special problem is the differentiation of position I-1 and L-3 of glycerol. In the presently known methods, triglycerides are first degraded to mixtures of diglycerides, either by the action of a lipase or by degradation with a Grignard reagent. The isomeric diglycerides are then resolved with the help of a stereospecific enzyme, either a diglyceride kinase or (after conversion of the diglycerides to phospholipids) a phospholipase. It is then possible to analyze or calculate the fatty acid composition for each position on the glycerol. The key to a successful stereospecific analysis is the preparation of a representative diglyceride mixture by a truly random degradation of the triglyceride. The Grignard degradation is the most reliable method, but it is not always applicable, and it is accompanied by some isomerization of glycerides. There is room for improvement in the method. Analyse of natural fats have shown most of them to be asymmetric, i.e., the composition of fatty acids in position 1 differs markedly from that of position 3. Several rules of fatty acid distribution have become apparent. Presented at the 62 nd Annual AOCS Meeting, Houston, May 1971.     

The structural analysis of wheat flour glycerolipids

The compositions of the fatty acids in the 1, 2 and 3 positions of the principal glycerolipids and their various stereoisomers were determined. Fatty acids in the 1 and 3 positions of triglycerides were similar in composition and less unsaturated than those in the 2 position. Fatty acids in the 1,2-, 1,3- and 2,3-diglycerides were distributed in a pattern which indicated isomerization ofsn-1,2-diacylglycerol. Lysophosphatidyl choline (the principal monoacyl lipid) consisted of about 80% 1-acyl and 20% 2-acyl isomers. The fatty acid compositions indicated that most of the 2-lysophosphatidyl choline was formed by isomerization of 1-lysophosphatidyl choline. Most of the digly cerides and lysophosphatidyl choline were synthesized in the ripening wheat grain. However a small proportion of these partial glycerides and all of the other minor partial glycerides (monoglycerides, digalactosyl monoglycerides) appeared to be the result of limited lipolysis of the corresponding diacyl lipids in the wheat or in the freshly-milled flour. Fatty acids in the 2 position of all the fully acylated glycerides were very similar in composition, but there were considerable differences in the 1 position fatty acids.     

Solvent extraction of lipid components from egg yolk solids

The effects of solvent systems on extraction of lipid components from commercially spray-dried egg yolks were investigated. Hexane, hexane:isopropanol (2:1), and chloroform:methanol (2:1) were studied, and the effects of temperature of extraction and ratio of solvent to egg were examined in a 3×2×2 factorial design. Hexane removed more fat and phospholipid and less cholesterol and pigment than the more polar solvents. Increased solvent ratio extracted more of the lipid components, although temperature of the extraction had little effect on removal of the lipid components.     

Utilization of docosahexaenoic acid from intravenous egg yolk phospholipid

Docosahexaenoic acid (DHA, 22∶6n−3) is provided directly to human premature infants during parenteral nutrition from the egg yolk fraction of an intravenous fat emulsion. This study aimed to determine whether the high egg yolk phospholipid content of Intralipid 10% (IL 10%, Pharmacia, Uppsala, Sweden) relative to the standard emulsion Intralipid 20% (IL 20%, Pharmacia) could be a strategy to increase the delivery of DHA to the developing brain. Male, Large White piglets were randomly selected from sows 3 d after birth. Piglets were assigned to receive a 9-d continuous intravenous infusion commencing 5 d after birth of either Intralipid (IL) 10%, IL 20%, or Lipofundin S 20% (LFS; B. Braun, Melsungen, Germany). There were four piglets in each treatment group. IL 10% provides twice as much DHA as IL 20%, while LFS provides no DHA. Protein and other nutrients were provided enterally using a low-fat milk formula. After 9 d, animals were killed, and the fatty acid compositions of blood, liver, and cerebral cortex were analyzed. IL 10% infusion approximately doubled the amount of plasma phospholipid DHA (μg/mL of plasma) in comparison to IL 20%. However, red blood cells, liver, and cerebral cortex phospholipid DHA levels were indistinguishable between these two groups. LFS was associated with reduced levels of DHA in plasma, red blood cell and liver phospholipids in comparison to IL 20%. We conclude that infusion of additional phospholipid is an ineffective strategy for increasing DHA delivery to piglet tissues. This may be due to the formation of inert phospholipid particles in plasma. The data do not support the concept of using IL 10% as a means of providing additional DHA to premature human infants.     

Elucidating enzyme-based cleaning of protein soils (gelatine and egg yolk) using a scanning fluid dynamic gauge

The enzyme-based cleaning of two model protein soils was investigated using a scanning fluid dynamic gauge (sFDG). The sFDG device allows data to be collected from more than one sample or location during a single experiment and therefore makes a range of comparative studies feasible. The sFDG was modified to allow the forces imposed on the surface to be controlled during a test. Gelatine films on stainless steel swelled in the presence of alkali at 20 °C but were not removed. Enzymes from a commercial dishwasher product interrupted swelling when the mean water volume fraction of the film reached ∼0.9 and promoted removal. The enzyme effectiveness decreased over time. Egg yolk deposits (spray dried on mica) were studied in a protease/buffer solution at 40 °C. The deposits swelled on contact with alkali, and removal started after ∼40 min. Some flow over the deposit was required to achieve complete cleaning, but the time taken to clean exhibited a weak dependence on the shear stress imposed by the flow for shear stresses above 10 Pa. The cleaning behaviour was strongly influenced by the nature of the deposit. Baking the deposit at 150 °C reduced the rate and extent of swelling as well as the rate of removal, and could result in the formation of a residual film that exhibited yield stress characteristics.     

Stereospecific analysis of maize triglycerides

This is the first report of stereospecific analyses of plant triglycerides isolated from seeds of distinct genotypes rather than from commerically refined oils. Triglycerides from six maize inbreds were analyzed. The strains exhibited a wide range of fatty acid compositions (palmitic acid 7.8–19.1%, oleic acid 17.0–43.0%, linoleic acid 41.6–68.3%). The distribution of the fatty acids among the 1, 2 and 3 positions of the triglycerides was clearly nonrandom for all six strains. At the 2 position of the triglycerides over 98% of the fatty acids were unsaturated. More plamitic and stearic acids were found in position 1 than in 3. The general fatty acid pattern of maize triglycerides was similar to that found in most animal triglycerides.     

Stereospecific analysis of soybean triacylglycerols

Thirty soybean germplasm lines representing a wide distribution of fatty acid compositions were analyzed stereospecifically by using a chiral column to resolve the sn-1 and sn-3 positions of glycerol. The amounts of each acyl group on each of the sn positions were plotted vs. the amount of that acyl group in the triacylglycerols (TAG), and the plots were fitted by linear regression. The deviation of individual data points from the linear regressions was much greater than observed in previous studies. This could be attributed to the inclusion of a number of germplasm lines with elevated or reduced percentages of saturates. The stereospecific distributions could not be fit with previously suggested mathematical models because the plots had intercepts that were not allowed by the models. Statistical tests of the analytical procedure indicated that slight oxidation of or bias against the polyunsaturates had occurred and that the Grignard deacylation method gave slightly less representative analyses of the sn-2 position than pancreatic lipase deacylation on these TAG.     

Stereospecific analysis of fish oil triacyl-sn-glycerols

Stereospecific analysis of fish oil triacyl-sn-glycerols was carried out by novel high-performance liquid chromatography on a chiral stationary phase. The positional distributions of fatty acids were determined without accumulation of errors in a particular position and preferential hydrolysis for a particular fatty acid. High-resolution gas-liquid chromatography on an open tubular column detailed the distribution of unsaturated fatty acid isomers having olefinic bonds in different positions. The distribution of fatty acids was not independent of other fatty acids. The distribution of long-chain highly unsaturated fatty acids 22:6(n-3), 22:5(n-3) and 20:5(n-3) was governed by total amounts of 20:1 and 22:1 in triacyl-sn-glycerols. Long-chain monounsaturated acids 20:1 and 22:1 were influenced by the position of the olefinic bond in 20:1 occurring in triacyl-sn-glycerols. Shorter-chain C14-C18 fatty acids seemed to be influenced by total fatty acid composition. These results introduce a concept of mutual interaction between fatty acids to the investigation of positional distribution of fatty acids.     

Stereospecific analysis of some cruciferae species

Results of stereospecific analysis of nine Cruciferae seed oils are presented. The major fatty acids in the oils investigated are nonrandomly distributed, not only between inner and outer positions, but also between sn-1 and sn-3 positions. When the positional data were plotted versus erucic acid content, a regular and characteristic distribution pattern for each fatty acid was obtained. Category I acids (saturated acids and acids with more than 18 carbon atoms) prefer either of the outer positions. Erucic acid, however, has a clear preference for the sn-3 position. When in the outer positions, Category II acids (unsaturated acids with 18 carbon atoms) as a rule prefer the sn-1 to the sn-3 position. This tendency increases with decreasing unsaturation.     

水稀释硫酸铵盐析法纯化卵黄抗体

以人的免疫球蛋白G1(IgG1)为抗原对无特定病原体(SPF)级来航鸡进行免疫,在34周内采集血清并收集所产鸡蛋,采用水稀释硫酸铵盐析法从鸡蛋卵黄中纯化得到了抗人IgG1的鸡卵黄抗体(IgY),测定了纯化工艺中每一步的蛋白收率,并对免疫周期内不同时间卵黄中抗体的质量浓度、亲和能力及特异性进行了考察。结果显示蛋白总收率为4.90%,其中超滤和沉淀是影响总收率的主要因素;血清和卵黄中抗体的质量浓度在第22—23周达到最大值;亲和常数在第8周达到最大,为1.1×109L/mol;IgY抗体与其他种属的IgG抗原不发生结合,是一种高特异性的抗体。该纯化方法不仅能够制备出纯度很高的抗体,而且工艺简单、经济,易于大规模生产。     

Stereospecific analysis of human plasma triglycerides

Brockerhoff-type procedures were used to determine the amounts of each fatty acid at each position of plasma triglycerides from normal and hyperlipemic humans. Statistically significant differences between both groups are found for the 2 and 3 positions.     

Effect of diet on triglyceride structure and composition of egg yolk lipids

Hens were fed a practical diet supplemented and unsupplemented with 5% menhaden oil and a synthetic fat-free diet for a period of 90 days. Egg yolks from hens fed each of the three diets were analyzed for fatty acid composition and positional distribution of the fatty acids by successive chromatographic techniques. The triglycerides were resolved into fractions containing, 0, 1, 2 and 3+ double bonds per molecule. Each of these types was quantitated and analyzed for fatty acid distribution. The positional distribution was determined with the aid of pancreatic lipase hydrolysis. The feeding of the practical diet supplemented with 5% menhaden oil produced an increase in the 14∶0 acid in the intact triglycerides, 2-monoglycerides and 1,3-diglycerides with the majority of this acid being bound in the 1,3 positions. In the monounsaturated triglycerides the 16∶0 acid was linked predominantly at the 1,3 positions. The feeding of the fat-free diet produced a decrease in the 16∶1 acid content of the egg yolk lipids in the monounsaturated series, in the intact triglycerides, the 2-monoglycerides and the 1,3-diglycerides. The 18∶0 acid was linked more often at the 1,3 positions than at the 2 position, and was not affected by the diet consumed by the hens. Hens fed the fat-free diet produced more monounsaturated and diunsaturated triglycerides than those fed the other diets. Linoleic acid exhibited the greatest degree of preference for the 2 position, which was followed in turn by oleic acid. All other major acyl components were found to be preferentially esterified at the 1,3 positions. The difference observed in the fatty acid composition of egg yolk neutral and polar lipids was attributable to the fatty acid content of the diet. In the case of the oleic and linoleic acids, there was less variation in the saturated fatty acid content, which could be traced to the type of diet fed.     

Volatile compounds induced by herbivory act as aggregation kairomones for the Japanese beetle (Popillia japonica Newman)

The Japanese beetle is a polyphagous insect that typically aggregates on preferred host plants in the field. We studied the response of Japanese beetles to artificial damage, fresh feeding damage, and overnight feeding damage to test the hypothesis that beetles are attracted to feeding-induced volatiles. Crabapple leaves that had been damaged overnight by Japanese beetles or fall webworms attracted significantly more Japanese beetles than did undamaged leaves. Artificially damaged leaves or leaves freshly damaged by Japanese beetles, however, were not significantly more attractive than undamaged leaves. Leaves that had been damaged overnight by Japanese beetles or fall webworms produced a complex mixture of aliphatic compounds, phenylpropanoid-derived compounds, and terpenoids. In comparison, artificially damaged leaves or leaves with fresh Japanese beetle feeding damage generated a less complex blend of volatiles, mainly consisting of green-leaf odors. Feeding-induced odors may facilitate host location and/or mate finding by the Japanese beetle.