Fatty acids composition and structure

Hay and Morrison (1971) later presented additional data on the fatty acid composition and structure of milk phosphatidylethanolamine and -choline. Additionally, phytanic acid was found only in the 1-position of the two phospholipids. The steric hindrance presented by the four methyl branches apparently prevents acylation at the 2-position. The fairly even distribution of monoenoic acids between the two positions is altered when the trans isomers are considered, as a marked asymmetry appears with 18 1 between the 1- and 2-positions of phosphatidylethanolamine, but not of phosphatidylcholine. Biologically, the trans isomers are apparently handled the same as the equivalent saturates because the latter have almost the same distribution. There are no appreciable differences in distribution of cis or trans positional isomers between positions 1 and 2 in either phospholipid. Another structural asymmetry observed is where cis, cis nonconjugated 18 2s are located mostly in the 2-position in both phospholipids. It appears that one or more trans double bonds in the 18 2s hinders the acylation of these acids to the 2-position. 

As mentioned above, oil-modified polyester resins possess a wide variety of structural compositions as they can be prepared from a large variety of vegetable oils. These vegetable oils possess different fatty acid compositions and structures. As the structure of a material determines its properties and behaviour, so these resins exhibit a wide range of properties which are... 

Capella, P., Lercker, G. and Tiscornia, E. (1979a) The chemical composition of grape seed oil. Note 1 Fatty acid composition and structure of glycerides. Riv. Ital. Sostanze Grasse 56, 297-299. 

Comparson of the transitions observed by differential scanning calorimetry in membranes of M. laidlawii and in water dispersions of the lipids from the membranes support the concept that most of the lipids exist as a smectic mesophase in the membranes. The evidence for a bilayer structure is straightforward in this case. Lipid transition temperatures are a function of fatty acid composition and correlate well with biological properties. The calorimeter possesses advantages over high resolution NMR for M. laidlawii, and perhaps in many other systems, because the data can be interpreted less ambiguously. In M. laidlawii membranes the bilayer appears to be compatible with the same physical properties observed in other membranes—a red-shifted ORD, lack of ft structure in the infrared, reversible dissociation by detergents, and poorly... 

The ELS detector was previously also referred to as a mass detector, pointing to the fact that the response is (mainly) determined by the mass of the sample rather than by its chemical structure. Van der Meeren et al., though, demonstrated that the ELSD calibration curves of phospholipid classes were also dependent on the fatty acid composition (52). The dependence on the fatty acid composition is, however, completely different in nature and much less pronounced than for UV detection. The reason for this behavior is to be found in the partial resolution of molecular species, even during normal-phase chromatography. Thus, the peak shape depends not only on the chromatographic system but also on the fatty acid composition and molecular species distribution of the PL sample (47). Because it was shown before, based on both theoretical considerations and practical experiments, that the ELS detector response is generally inversely proportional to peak width (62,104), it follows that the molecular species distribution of the PL standards used should be similar to the sample components to be quantified. It was shown that up to 20% error may be induced if an inappropriate standard is used (52). 

Lipids play an important part in the development of aroma in cooked foods, such as meat, by providing a source of reactive intermediates which participate in the Maillard reaction. Phospholipids appear to be more important than triglycerides. The addition of phospholipid to aqueous amino acid + ribose mixtures leads to reductions in the concentrations of heterocyclic compounds formed in the Maillard reaction. This effect could be due to lipid oxidation products reacting with simple Maillard intermediates, such as hydrogen sulfide and ammonia, to give compounds not normally found in the Maillard reaction. The precise nature of the odoriferous products obtained from lipid - Maillard interactions is dictated by the lipid structure and may depend on the fatty acid composition and the nature of any polar group attached to the lipid. 

Sciancalepore, V. and Dorbessan, W. (1981) Effect of variety on fatty acid composition and glyceride structure of avocado oil. Riv. Agri. Subtrop. Trop., 75, 109-115. 

The major differences between the lipids of bovine and human milk are in fatty acid composition and triacylglycerol structure. Bovine milk contains substantial quantities of C4 o-Ci0 o, about 2% Cis 2 and almost no other long-chain polyunsaturated fatty acids. The fatty acid composition is not altered by ordinary changes in diet. Human milk contains very little C4 o-C10 o, 10-14%i (w/w of fat) Ci8 2, and small quantities of other polyunsaturates. The triacylglycerol structure differs, with much of the sn-2 position in human milk lipids occupied by C16 0 and the sn-2 position of bovine milk-fat occupied by C4 o-Ci0 o-... 

The effects of Caprenin, another structured lipid, on chylomicron fatty acid composition and postprandial semm lipid concentrations have also been studied (178). It was found that there is a very low uptake of C8 0, C10 0, and C22 0 into chylomicrons. Moreover, a postprandial lipemia after caprenin is comparable with that produced by other dietary fats as opposed to a fat-free meal. There is considerable... 

Marine mammal oils or their co3 concentrates can also be modified for different applications. Modifications include the changing of the fatty acid composition and/ or their location in the glycerol backbone. Structured lipids containing both 0)3 long-chain PUFAs, possibly from seal blubber oil, or their co3 concentrates, and medium-chain fatty acids (MCFAs), which are saturated fatty acids with 6-12... 

In this chapter, molecular factors affecting structural behavior of fat polymorphism are discussed in terms of internal influences of the TAG molecules. In particular, the influences of fatty acid compositions and their positions connected to glycerol carbons on the polymorphism of fat crystals are of primary concern. It has been known that the fats with simple and symmetric fatty acid compositions tend to exhibit typical oc, P, and P forms, whereas those with asymmetric mixed-acid moieties often make the P form more stable (1,9). In the mixed-acid TAG containing unsaturated fatty acid moieties, the number and conformation of the double bond, cis or trans, give rise to remarkable influences on the polymorphic structures (10-12). The TAG containing different saturated fatty acids with different chain-lengths also revealed quite diversified polymorphism (13-15). Therefore, it may be worthwhile now to discuss the molecular aspects of the polymorphism of fats. This consideration may also be a prerequisite for molecular design of structured fats, in combination with nutritional and metabolic properties. 

Connor WE, Neuringer M. The effects of n-3 fatty acid deficiency and repletion upon the fatty acid composition and function of the brain and retina. In Kamovsky ML, Leaf A, Bolis LC, eds. Biological Membranes Aberrations in Membrane Structure and Function. Alan R Liss, New York, 1988, pp. 275-294. 

Two other major benefits have been derived from the Arabidopsis lipid mutants. First, the physiological effects of the mutations have provided the opportunity to evaluate the relationships between lipid structure and function. There has been a long-term assumption, based on the strong association of high levels of polyunsaturated fatty acids with photosynthetic membranes and the conservation of this property among higher and lower plant species, that these fatty acids must be essential for photosynthesis. However, many attempts to understand the relationships between membrane fatty acid composition and cell physiology or photosynthesis have led to equivocal results. The isolation of mutants... 

Although structures of these glycolipids were analyzed in the past by gas chromatography-mass spectrometry (GC-MS) of derivatives such as trimethylsilyl (TMS) ethers [14-16], the characterization in this work, which involves determination of the fatty acid composition and the location of double bonds in the long-chain base (Cw-sphingadienine), is carried out by B/E linked scan FAB mass spectrometry of the glycolipids itself... 

The term Designer Lipids comprises artificial glycerides, synthesized either chemically or enzymatically, with a specific fatty acid composition and/or a specific regioselective pattern, the latter ones called structured lipids. Enzymatic... 

Duncan, W.R. Garton, G.A. 1968. The fatty acid composition and intramolecular structure of triglycerides from adipose tissue of the hippopotamus and the African elephant. Comp. Biochem. Physiol., 25, 319—325. 

Changes in the fatty acid composition of structural lipids in brain membranes have been reported to modify (Na+K)-ATPase in synaptosomes (Sun Sun, 1975) and n-6 and n-3 fatty acids are considered important for the activity of certain membrane-bound enzymes (Bernsohn Spitz, 1974). Modifications in learning... 

TROPICAL fruits A SOURCE OF LIPIDS Table 5.4 Fatty acid composition and glyceride structure... 

Each phospholipid class in a given tissue has a characteristic fatty acid composition. Though the same fatty acid may be present in a number of lipids, the quantitative fatty acid composition is different for each class of lipids and remains fairly constant during the growth and development of the brain. A typical distribution profile of the major fatty acids in rat brain phospholipids is given in Table 3.1. Not only do the phosphoglycerides differ in the structure of the polar head groups, or phospholipid... 

Other workers began to study the structure of gramicidin. Christensen and coworkers12 isolated crystalline tryptophane and leucine from a hydrolysate. They found no evidence for a fatty acid component and established that phenylalanine, proline and hydroxyproline were absent from a hydrolysate. These workers isolated alanine diox-pyridate from a hydrolysate and also established that gramicidin contained a compound with vicinal hydroxy and amino groups. They speculated that this compound might be serine or isoserine and proposed that gramicidin contains two tryptophane, 2 leucine, 2 or 3 alanine and 1 hydroxyamino residues or a multiple of this composition. 

Kurbanov, I. Gullyev, M.N. TcsIct, I.D. Onov, A. Khekimov, Y.K. (1997) Composition and structure of biologically active fatty acids of Caspian Sea algae. Zdravoddir. Turkm. (3), 17-20 Chmi. Abstr., 1998, 128, 59227U. 

Triacylglycerols. The composition of TGs refers to their structure or the identity of the fatty acids esterified to each of the three hydroxyls on glycerol and ultimately to the identity of the individual molecular species. Because there may be over 400 fatty acids in a milk sample, based on random distribution, there may be a total of 4003 or 64 x 106 individual TGs, including all positional and enantiomeric isomers. A random distribution is defined as all possible combinations resulting from expansion of the binomial equation. If we have two fatty acids, x and y, located at random in the three positions of glycerol, the equation becomes (x + y)3 or x3 + 3x2y + 3 xy2 + y3, which, when expanded further, is x3 = xxx, 3x2y = xxy, 3 xy2 = yyx, y3 = yyy yxx xyy... 

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