Addition Of Egg Lecithin Research Articles

A Selective Separation Method for Slower‐Growing Bacteria from Marine Soils

Egg lecithin greatly reduced the antibacterial activities of chlorhexidine gluconate (CHG). By using this antagonistic action, slower‐growing bacteria, for which a longer incubation time was needed for its growth, were isolated from marine soils. The growth of relatively faster‐growing bacteria, which formed visible colonies during a 3 day incubating period, was significantly inhibited by treatment with 8 µg of CHG per mL for 10 min, whereas the addition of egg lecithin to a final concentration of 2%, after the treatment, had no significant effect on the viability of slower‐growing bacteria.

Phosphatidylcholine turnover during senescence of rose petals

Senescence of rose ( Rosa hyb., cv. Mercedes) petals is accompanied by intensive modifications in membrane properties, where a decline in phospholipid content is a major change. Pulse-chase experiments with [ 14C]choline chloride revealed that the decline in phosphatidylcholine (PC) with age is a result of a lower biosynthetic capacity of older petals and not of an increased degradation. The enzyme cytidine-diphospho-choline diacylglycerol phosphorylcholine phosphotransferase (CDP-cholinephosphotransferase, EC 2.7.8.2) was therefore studied in detail. This enzyme is involved in PC synthesis and its activity was demonstrated in microsomal fractions and found to be similar to that reported for other plant systems. The enzyme's V max was higher in microsomes of young petals than of old ones. This, coupled with the reduction in protein content, resulted consequently in a decline in the total activity of the enzyme during the petal senescence. Modifications in the thiol groups of the membrane proteins resulted in changes in the enzyme activity. The activity of the enzyme was enhanced by the addition of egg lecithin and partially inhibited by cholesterol. In addition, it was altered by detergents known to influence the enzyme's membranous microenvironment. Senescence of petals has previously been shown to be accompanied by a decrease in membrane lipid fluidity and protein thiol content. Therefore it is possible that the observed age-related changes in enzyme activity, which lead in turn to the overall reduction in petal phospholipid content, are a result of these membrane changes.

Asperfuran, a novel antifungal metabolite from Aspergillus oryzae.

Asperfuran is a novel antifungal dihydrobenzofuran derivative produced by a strain of Aspergillus oryzae. Asperfuran weakly inhibited chitin synthase from Coprinus cinereus. This inhibition could be abolished by the addition of egg lecithin. In the agar diffusion assay asperfuran induced morphological changes in Mucor miehei at very low concentrations (20 ng/disc) while growth was only partly inhibited. In HeLa S3 and L1210 cells it showed weak cytotoxicity, the IC50 was 25 micrograms/ml.

Role of low density lipoprotein in the activation of plasma lysolecithin acyltransferase activity: Effect of chemical and enzymatic modifications of the lipoprotein on enzyme activity

The effect of various chemical and enzymatic modifications of low density lipoprotein (LDL) on its ability to activate the isolated human plasma lysolecithin acyltransferase (LAT) was studied. Removal of all lipids from LDL resulted in the complete loss of LAT activation. Removal of only neutral lipids by extraction with heptane retained up to 50% of the original activity, which was not increased further by reconstitution of the LDL with the extracted lipids. Hydrolysis of the diacylphosphoglycerides of the LDL with phospholipases resulted in complete loss of LAT activation which was partially restored by the addition of egg lecithin. Hydrolysis of more than 4% of LDL protein by trypsin led to a linear decrease in activity with complete loss of activity occurring when about 25% of the LDL protein is hydrolyzed. Modification of the arginine groups of LDL reversibly inhibited the activation of LAT. Modification of lysine residues of LDL by acetylation, acetoacetylation or succinylation also abolished its ability to activate lysolecithin acylation. Cationization of the lipoprotein destroyed its activity, but the reduction and alkylation only decreased the activity slightly. Complete removal of sialic acid groups by treatment of LDL with neuraminidase reduced the activation of LAT by about 20%. From these results it is concluded that the phospholipids of LDL and the charged groups of LDL apoprotein B are essential for its activation of the acylation of lysolecithin by the lysolecithin acyltransferase of human plasma.

Evidence for a phospholipid requirement of chitin synthase inSchizophyllum commune

Evidence for a lipid dependence of membrane-associated chitin synthase inSchizophyllum commune is based on the following observations: Arrhenius plots of the temperature dependence of this enzyme showed deflections from linearity that are characteristic for lipid-affected membrane-bound enzymes. The activity of chitin synthase dissociated by digitonin decreased at increasing digitonin/protein ratios and could be restored by addition of egg lecithin. After further delipification by sucrose gradient centrifugation, enzyme activity progressively decreased, banded at higher densities, and was less effectively restored by lecithin. The activity of dissociated chitin synthase was also restored by soybean phosphatidylcholine and low concentrations of phosphatidylinositol and phosphatidylserine. At higher concentrations, phosphatidylinositol and phosphatidylserine were inhibitory. Lysophosphatidylcholine and phosphatidylethanolamine were slightly stimulatory, whereas no effect resulting from ergosterol was observed.

Intestinal absorption of dl-alpha-tocopherol from bile salts and polysorbate 80 micellar solutions in rat.

The intestinal absorption of dl-alpha-tocopherol (VE) from various micellar solutions was studied by the in situ recirculating perfusion in rat small intestine. The perfused micellar solutions of VE were formed by sodium taurocholate (STC), sodium taurodeoxycholate (STDC) or polysorbate 80 (PS-80). The absorption ratio of VE was STC greater than STDC greater than PS-80 micellar solutions. The addition of egg lecithin (PC) to all micellar solutions caused the decrease of the absorption. The absorption ratio did not necessarily have a simple correlation with the VE solubilization in these micellar solutions. And it was also found that the absorption ratio correlated with the micellar size and with net water flux in the intestinal lumen.

Purification of apo-3-D-(-) hydroxybutyrate dehydrogenase from rat liver mitochondria.

3-D-(-) hydroxybutyrate dehydrogenase (EC 1.1.1.30) from rat-liver mitochondria was purified in the form of the soluble, phospholipid-free apoenzyme by a procedure involving: (1) solubilization of the membrane bound enzyme by controlled digestion of membrane phospholipids with porcine pancreas phospholipase A2; (2) stabilization and separation of the released apoenzyme as a complex with egg-lecithin by gel filtration on Sephadex G-100; and (3) specific displacement of the apoenzyme from the enzyme-lecithin complex by treatment withBothrops atrox venom phospholipase A2 (in the absence of Ca2+ ions) and subsequent separation of the displaced apoenzyme by gel filtration on Sephadex G-100. The method described is adequate for samples containing about 40 mg of mitochondrial protein. The yield in activity is 42% of that present in mitochondria and the degree of purification of the apodehydrogenase is about 170 fold. The purified apodehydrogenase shows one single sharp band when submitted to SDS polyacrylamide gel electrophoresis, with a mobility corresponding to a molecular weight of 38000 daltons. Gel filtration of the apoenzyme on Sephadex G-100 shows two active peaks with molecular weights of 76000 and 38500 daltons, indicating two different states of aggregation, namely, monomer and dimer. The corresponding diffusion coefficients are 7.73 (monomer) and 5.70 (dimer) × 10−7. The apodehydrogenase preparation is devoid of phospholipids and is catalytically inactive. It can be reactivated by addition of egg lecithin or phospholipid mixtures containing lecithin in a suitable physical state. Reactivation occurs after formation of an active apodehydrogenase phospholipid complex.

Control of bitter pit in apples with lecithin and calcium

Abstract The incidence of bitter pit in ‘Cox’s Orange Pippin' apples was halved when the apples were dipped after harvest in solutions containing 2.5% CaCl2 or Ca(NO3)2. Addition of egg lecithin to the dips further reduced the incidence of the disorder (to less than one quarter of that in water-dipped controls). Lecithin addition also alleviated the damage often associated with calcium dips and improved control of two other physiological disorders, breakdown and water core. A dip containing lecithin alone was relatively ineffective. It is suggested that lecithin may assist the movement of applied calcium into apples.

The effect of phospholipase C on the activity of adenosine triphosphatase and acetylcholinesterase in synaptic membranes isolated from the cerebral cortex of squirrel monkey.

AbstractA synaptic‐membrane fraction rich in junctional components and Na‐K ATPase and AChE activity was isolated from the cerebral cortex of the squirrel monkey. Incubation of membrane preparations with phospholipase C decreased the activity of Na‐K ATPase by 50 per cent but had no effect on the activity of AChE. Analysis of the membrane fraction showed that phospholipase C cleaved both choline phosphoglyceride and the diacyl type of ethanolamine phosphoglyceride from membrane lipids. Addition of egg lecithin at low concentrations partially restored the activity of Na‐K ATPase. Kinetic studies revealed that treatment with phospholipase C may produce a non‐competitive type of inhibition as a result of the cleavage of a charged phosphorylated nitrogen base from membrane lipids.

Bile salt-induced permeability changes in the isolated rat intestine.

SummaryPhysiologic concentrations of the conjugated bile salt, sodium taurodeoxycholate, markedly increased the permeability of the everted rat small intestine to salicylate ion. Addition of egg lecithin or oleic acid and glyceryl monooleate to the medium diminished this effect and prevented changes in the gross appearance of the intestinal mucosa which occurred when the isolated intestine was exposed to the bile salt alone.