Fatty acid occurrence

Grechkin AN (1995) Clavulones and Related tert-Hydroxycyclopentenone Fatty Acids Occurrence, Physiological Activity and Problem of Biogenetic Origin. J Lipid Mediators Cell Signal 11 205... 

Ants, sterol metabolism, 131,13, 133 Archaebacteria, fatty acid occurrence, 174/175-176... 

Acyl groups are common in bacterial polysaccharides. The parent acids are fatty acids, hydroxy acids, and amino acids. The simplest acid, formic acid, has only been found as the amide. The occurrence of O-formyl groups had been reported, but proved to be incorrect. A-Formyl groups have been found in different polysaccharides for example, in the 0-specific side-chains of the LPS from Yersinia enlerocolitica 0 9, which are composed of 4,6-dideoxy-4-formamido-D-mannopyranosyl residues. The formyl group can assume two main conformations, s-cis (41) and s-trans (42), which are... 

FATTY ACIDS A BRIEF OVERVIEW OF CHEMISTRY AND OCCURRENCE... 

Table 11.1 Systematic and common names of saturated fatty acids together with the shorthand designation and typical occurrence (compiled from Gunstone et al., 1994 Hilditch and Williams, 1964 Perkins, 1993 Robinson, 1982). The shorthand designation denotes Cx n where x is the number of carbon atoms and n is the number of double bonds.

Glucocorticoids not only break down protein but also stimulate the catabolism of lipids in adipose tissue and enhance the actions of other lipolytic agents. This occurrence results in an increase in plasma free fatty acids and an enhanced tendency to ketosis. The mechanism of this lipolytic action is unknown. The net effect of the biochemical changes induced by the glucocorticoids is antagonism of the actions of insulin. These biochemical events promote hyperglycemia and glycosuria, which are similar to the diabetic state. 

In a similar manner, many additions of heteroatom radicals to unsaturated positions have been studied. In many cases, addition reactions of heteroatom radicals to alkenes are reversible and thermodynamically disfavored, but their occurrence is apparent. For example, the rapid addition and elimination of thiyl radicals to unsaturated fatty acid methyl esters results in isomerization reactions from which kinetic parameters can be obtained. Additions of group 14 (IV A) metal-centered... 

Many of the picornavirus structures have been shown to have electron density in their VP1 pockets even in the absence of any added drug. These densities have been modeled as fatty acids or similar compounds [12,15,56,70-72]. The occurrence of these pocket factors have led some to hypothesize that these factors perform a similar function as do capsid-binding inhibitors, that is, to stabilize the virions [15,24,41,73,74]. 

Fatty acid chains may contain no double bonds—that is, be satu rated, or contain one or more double bonds—that is, be mono- or polyunsaturated. When double bonds are present, they are nearly always in the cis rather than in the trans configuration. (See p. 362 for a discussion of the dietary occurrence of cis and trans unsatu- rated fatty acids.) The introduction of a cis double bond causes the I tfatty acid to bend or "kink" at that position (Figure 16.3). If the fatly acid has two or more double bonds, they are always spaced at three carbon intervals. [Note In general, addition of double bonds decreases the melting temperature (Tm) of a fatty acid, whereas j increasing the chain length increases the Tm. Because membrane lipids typically contain LCFA, the presence of double bonds in some fatty acids helps maintain the fluid nature of those lipids.]... 

Han, J., Calvin, M., Occurrence of Fatty Acids and Aliphatic Hydro-... 

Stenhagen, S., Occurrence of Isoprenoid Fatty Acids in the Green River Shale, Science (1966) 153 (3731), 1133-1134. 

Monobasic Acids. The overwhelming majority of monobasic acids used in alkyd resins are long-chain fatty acids of natural occurrence. They may be used in the form of oil or free fatly acid. Free laity acids arc usually available and classified by dieir origin, viz, soya fatly acids, linseed fatty acids, coconut fatty acids, etc. Fats and oils commonly used in alkyd resins include castor oil. coconut oil, eotlonseed oil. linseed oil, oilicica oil, peanut oil. rapeseed oil, safflower oil, soyabean oil, sunflowerseed oil. and tung oil. 

The order of elution is governed by the length of the fatty acid carbon chain and the number of double bonds in it. These opposing tendencies lead to the occurrence of several pairs of fatty acids that are difficult to separate and the separation of which may be considered a criterion of the resolution efficiency of an analytical procedure. 

These data suggest that processed meats (e.g., hot dogs, bologna, and salami) contain more chemicals than muscle products (e.g., steak or chicken breast). This could be a function of the fat content of these processed meats. In general, beef products are more contaminated than pork products, whereas poultry have very few contaminants. Clearly, there appears to be some correlation between the amount of fat in protein products and the occurrence of synthetic chemicals in a given product. The number of chemical contaminates in fish may also be correlated to the occurrence of fatty acids. For example, salmon and tuna are known to have more fatty acids than haddock. Therefore, it is expected that salmon would contain more contaminants than haddock. 

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