Phospholipids species

CHOI J H, CHA B K and RHEE s J (1998) Effects of green tea catechin on hepatic microsomal phospholipase A2 activities and changes of hepatic phospholipid species in streptozotocin-induced diabetic rats , JNutr Sci Vitaminol (Tokyo), 44 (5), 673-83. 

Megli and Sabatini [55] studied the phospholipid bilayers after lipoperoxidation. Phospholipids were oxidized, and the oxidized phospholipid species were separated by PLC and estimated by EPR. It was shown that the early stages of lipoperoxidation brought about disordering of the phospholipid bilayer interior rather than fluidity alterations and that prolonged oxidation may result in a loss of structural and chemical properties of the bilayer until the structure no longer holds. 

This is the most polar group of lipids in natural lipid samples. When developed in a nonpolar solvent system, phospholipids remain at the origin and more polar solvent system should be used to elute and separate individual phospholipids. The most popular system is the Wagner system, which consists of chloroform metha-nohwater (65 25 4) [51] for the separation of common phospholipid species in natural tissue samples. 

A final example of the uniqueness of phospholipid structure and composition in cells relates to the fatty acyl (or the hydrocarbon moiety) groups of particular lipid species in cells. Again this distribution, to be illustrated below, is very constant in normal cells and yet raises the question as to why specific phospholipids have a penchant for certain fatty acyl (hydrocarbon) groups which is not exhibited by other phospholipid species in the cell. This question is clearly posed in the data shown in Table 1 -6. This is an abbreviated examination of only a few cells, but a similar profile occurs in many other cells as well. 

The major challenge in any study in which phospholipids are central components in a biological reaction of interest or in which there is evidence for a new type of phospholipid is their identification. While there are many excellent techniques available to accomplish this goal, there is absolutely no magic route to a satisfactory identification of specific phospholipids in a crude lipid extract except through the use of separation procedures. Basically it is next to impossible to identify or detect a specific phospholipid species in such a complex mixture. Thus, one must bite the bullet and resort to several analytical techniques for definitive proof. Perhaps the most important facet of this approach is that the compounds must be extracted from a tissue and then subjected to chromatographic separation. 

Dairy phospholipids are important structurally, because they are able to stabilise emulsions and foams, and to form micelles and membranes (Jensen and Newburg, 1995). Phospholipids also have the potential to be pro-oxidants, because they contain mono-unsaturated and poly-unsaturated fatty acids and have the ability to attract metal ions. Phosphatidyl ethanolamine binds copper strongly and is believed to be important in copper-induced oxidation in milk (O Connor and O Brien 1995 Deeth, 1997). The polyunsaturated fatty acids and metal ions accelerate lipid oxidation, especially when heat is applied hence, phospholipids can be degraded during the processing of milk. However, in dairy products, the situation is complex and it appears that phospholipids are able to act as either pro-oxidants or antioxidants, depending on the pH, ratio of water and phospholipid species (Chen and Nawar, 1991). 

On the other hand, the increased GPx activity (possibly via protein synthesis) might be associated with an oxidative stress induced by DHA (22 6, endogenous pool in the course of the DHA (22 6, -3) estoified to tri ycerides is rapidly redistributed within blood lipxqnioteins. The DHA (22 6, w-6) bound and circulate with the albumin fraction not only inhibit platelet aggregation but also influences its uptake into phospholipid species by target tissues (98). DHA therefore seems to impact platelet fatty acid metabolism through unique and novel mechanisms. 

White, T., Bursten, S., Frederighi, D., Lewis, R.A. and Nudelman, E., Fligh-resolution separation and quantification of neutral lipid and phospholipids species in mammalian cells and sera by multi-one-dimensional thin-layer chromatography. Anal Biochem, 10 (1998) 109-117. 

E. coli possesses only three major phospholipid species in its membranes, making it one of the simplest organisms to study with regard to phospholipid biosynthesis. Phosphatidylethanolamine (PE) comprises the bulk of the phospholipids (75%), with PtdGro and Ptd2Gro forming the remainder (15-20% and 5-10%, respectively). The scheme for the synthesis of membrane phospholipids follows the classic Kennedy pathway (Fig. 6). 

Fig. 6. Synthesis of phospholipid polar head groups. The three major phospholipid species in E. coli are synthesized by a total of six different enzymatic activities (1) phosphatidate cytidylyltransferase (Cds), (2) phosphatidylserine synthase (PssA), (3) phosphatidylserine decarboxylase (Psd), (4) phosphatidyl-glycerol phosphate synthase (PgsA), (5) phosphatidylglycerol phosphate phosphatase (PgpA or PgpB), and (6) cardiolipin synthase (els).

Amini, N. (2001) Development of enzymatic flow injection systems for the determination of phospholipid species in environmental samples. MSc thesis, Monash University, Clayton, Australia. 

Approximately 30% of position sn-2 in human platelet phospholipids consists of arachidonate. Of course, the percentage of arachidonate varies within the different phospholipids species and the amounts of the different species of phospholipid vary in the platelet. This is illustrated in Table 1.1. which shows that sphingomyelin contains essentially t-o arachidonic acid while ethanolamine-phospholipids contain the most arachidonic acid. Although phosphatidylinositol is the phospholipid species that is most enriched in arachidonic acid, its contribution to the total content of arachidonate in blood platelets is smalP. ... 

In the analysis of phospholipids from brain tissue section, over 30 experiments were performed on a single tissue sample before re-application of matrix. Performing multiple experiments on a single tissue section provided the opportunity to analyze multiple MS/MS spectra collected from the entire tissue section these data showed that at several m/z-values, three different phospholipid species were identified (PC, phosphtidylethanolamine (PE), and PS). Furthermore, at every single wt/z-value selected for an MS/MS experiment, a DHB cluster ion was detected (primarily based on the loss of 136 Da). 

Uran, S. Larsen, A. Jacobsen, P.B. Skotland, T. Analysis of phospholipid species in human blood using normal-phase liquid chromatography coupled with electrospray ionization ion-trap tandem mass spectrometry. J. Chromatogr. B, 2001, 758 (2), 265-275. 

Compositions of fatty acids in hydrazine-treated mitochondrial membranes showed decreases in relative amounts of palmitic (16 0) and stearic (18 0) acids and increases in those of oleic (18 1) and lin-oleic (18 2) acids (Wakabayashi etal. 1987). Among the relative amounts of phospholipid species, the increases in amounts of phosphatidylinosi-tol, phosphatidylserine, and phosphatidylethanola-mine were observed. A ratio of phosphatidyletha-nolamine vs. phosphatidylcholine was also increased. 

Fig. 12.2. MS images from one data file for 16 phospholipid species. See Table 12.2 for the identification of each ion. The maximum value of the intensity scale is indicated at the bottom left of each image. All images were normalized to the total Ion current.

Off-line coupling of HILIC and the reversed phase was realized by lisa and coworkers for lipidomic profiling of biological tissues [76] using both UV and MS detection (namely, ESI for polar phospholipid species and APCI interface for nonpolar TAG species). 

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