Fatty acid structures-Fatty Acids - Chemistry LibreTexts

Crotonic acid has 4 carbons, is included in croton oil , and is a trans mono-unsaturated fatty acid. CAS registry number Myristoleic acid has 14 carbons, is found in whale blubber , and is a cis monounsaturated fatty acid. CAS Registry Number Palmitoleic acid has 16 carbons, is found in cod liver oil , sardine oil , and herring oil , and is a cis 9-monounsaturated fatty acid.

Fatty acid structures

Fatty acid structures

Fatty acid structures

Fatty acid structures

Fatty acid structures

If membranes contain trans fats in them, the membrane fluidity will be affected. Erucic acid has 22 Fatty acid structures, is found in rapeseed oil and mustard oil Fatty acid structures, and is a cis monounsaturated is a fatty acid. Picual" PDF. Dietary chlorophyll cannot be hydrolysed to phytol in the digestive system of humans, but rumen microorganisms can accomplish this. Soaps are the sodium and potassium salts of fatty acids. Although all the carbon atoms of the fatty acids found in lipids are derived from the acetyl coenzyme A produced by the catabolism of carbohydrates and fatty acids, the molecule first undergoes a carboxylation, forming malonyl coenzyme A, before participating in fatty Fatty acid structures. The double bonds get saturated. Duck fat [27]. Eicosatrienoic acid eicosatrienoic's, eicosatrienoic acid has 20 carbons structure is Teen latino male models 11,14, tri unsaturated fatty acid.

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Stearidonic acid Free feet and pussy pics has 18 carbons, is found in sardine oil and herring oil, and is a 6,9,12,tetraunsaturated fatty acid. The recommendation of ingesting fish oil supplements during pregnancy is said Fatty acid structures help increase the cognitive ability at 6 months, but mercury concentration in fish products offsets the effect. Glycerin is a common name for glycerol. History at your fingertips. This is an omega-9 monounsaturated fatty acid. Carbohydrates are converted into pyruvate by glycolysis as the first important step in the conversion of carbohydrates into fatty acids. Department of Agriculture. NDL : Although all the carbon atoms of the fatty acids found in lipids are derived from the acetyl coenzyme A produced by the catabolism of carbohydrates and fatty acids, the molecule first undergoes a carboxylation, forming malonyl coenzyme A, before participating in fatty acid…. Fundamentals of Biochemistry 2nd ed. These names frequently do not follow any pattern, but they are Fatty acid structures and often unambiguous. Commercially, unsaturated oils are hydrogenated to improve shelf-life and prevent rancidification. The carbon atoms connected to Fatty acid structures other by the double bond are unsaturated with hydrogen. In this fatty acid there is a double bond between carbon 9 and 10 counting from Black lesbian squriting xxx CH 3 terminal carbon omega. Omega-3 and omega-6 fatty acids are biosynthetic precursors to endocannabinoids with antinociceptiveanxiolyticand neurogenic properties.

Fatty acid , important component of lipids fat-soluble components of living cells in plants, animals, and microorganisms.

  • Fatty acid , important component of lipids fat-soluble components of living cells in plants, animals, and microorganisms.
  • Crotonic acid has 4 carbons, is included in croton oil , and is a trans mono-unsaturated fatty acid.
  • In chemistry , particularly in biochemistry , a fatty acid is a carboxylic acid with a long aliphatic chain, which is either saturated or unsaturated.

In chemistry , particularly in biochemistry , a fatty acid is a carboxylic acid with a long aliphatic chain, which is either saturated or unsaturated. In any of these forms, fatty acids are both important dietary sources of fuel for animals and they are important structural components for cells. The differences in geometry between the various types of unsaturated fatty acids, as well as between saturated and unsaturated fatty acids, play an important role in biological processes, and in the construction of biological structures such as cell membranes.

Fatty acids with an odd number of carbon atoms are called odd-chain fatty acids , whereas the rest are even-chain fatty acids. The difference is relevant to gluconeogenesis. When circulating in the plasma plasma fatty acids , not in their ester , fatty acids are known as non-esterified fatty acids NEFAs or free fatty acids FFAs. FFAs are always bound to a transport protein , such as albumin.

Fatty acids are usually produced industrially by the hydrolysis of triglycerides , with the removal of glycerol see oleochemicals. Phospholipids represent another source. Some fatty acids are produced synthetically by hydrocarboxylation of alkenes [ citation needed ].

The process is based on the introduction or saturation of peroxides into fatty acid esters via the presence of ultraviolet light and gaseous oxygen bubbling under controlled temperatures. Specifically linolenic acids have been shown to play an important role in maintaining the moisture barrier function of the skin preventing water loss and skin dehydration. However, topically applied olive oil was not found to be inferior in a " randomised triple-blind controlled non-inferiority" trial conducted in Spain during In animals, fatty acids are formed from carbohydrates predominantly in the liver , adipose tissue , and the mammary glands during lactation.

Carbohydrates are converted into pyruvate by glycolysis as the first important step in the conversion of carbohydrates into fatty acids.

However, this acetyl CoA needs to be transported into cytosol where the synthesis of fatty acids occurs. This cannot occur directly. To obtain cytosolic acetyl-CoA, citrate produced by the condensation of acetyl-CoA with oxaloacetate is removed from the citric acid cycle and carried across the inner mitochondrial membrane into the cytosol.

The oxaloacetate is returned to the mitochondrion as malate. Malonyl-CoA is then involved in a repeating series of reactions that lengthens the growing fatty acid chain by two carbons at a time. When synthesis is complete the free fatty acids are nearly always combined with glycerol three fatty acids to one glycerol molecule to form triglycerides , the main storage form of fatty acids, and thus of energy in animals.

However, fatty acids are also important components of the phospholipids that form the phospholipid bilayers out of which all the membranes of the cell are constructed the cell wall , and the membranes that enclose all the organelles within the cells, such as the nucleus , the mitochondria , endoplasmic reticulum , and the Golgi apparatus. The "uncombined fatty acids" or "free fatty acids" found in the circulation of animals come from the breakdown or lipolysis of stored triglycerides.

The levels of "free fatty acids" in the blood are limited by the availability of albumin binding sites. They can be taken up from the blood by all cells that have mitochondria with the exception of the cells of the central nervous system. Fatty acids can only be broken down in mitochondria, by means of beta-oxidation followed by further combustion in the citric acid cycle to CO 2 and water.

The following table gives the fatty acid, vitamin E and cholesterol composition of some common dietary fats. Fatty acids exhibit reactions like other carboxylic acids, i. Fatty acids do not show a great variation in their acidities, as indicated by their respective p K a. Nonanoic acid , for example, has a p K a of 4.

As the chain length increases, the solubility of the fatty acids in water decreases, so that the longer-chain fatty acids have minimal effect on the pH of an aqueous solution. Even those fatty acids that are insoluble in water will dissolve in warm ethanol , and can be titrated with sodium hydroxide solution using phenolphthalein as an indicator.

This analysis is used to determine the free fatty acid content of fats; i. Neutralization of fatty acids, i. Hydrogenation of unsaturated fatty acids is widely practiced. Typical conditions involve 2. This treatment affords saturated fatty acids. The extent of hydrogenation is indicated by the iodine number. Hydrogenated fatty acids are less prone toward rancidification.

Since the saturated fatty acids are higher melting than the unsaturated precursors, the process is called hardening. Related technology is used to convert vegetable oils into margarine. During partial hydrogenation, unsaturated fatty acids can be isomerized from cis to trans configuration. In the Varrentrapp reaction certain unsaturated fatty acids are cleaved in molten alkali, a reaction which was, at one point of time, relevant to structure elucidation. Unsaturated fatty acids undergo a chemical change known as auto-oxidation.

The process requires oxygen air and is accelerated by the presence of trace metals. Vegetable oils resist this process to a small degree because they contain antioxidants, such as tocopherol. Fats and oils often are treated with chelating agents such as citric acid to remove the metal catalysts.

Unsaturated fatty acids are susceptible to degradation by ozone. In chemical analysis, fatty acids are separated by gas chromatography of methyl esters; additionally, a separation of unsaturated isomers is possible by argentation thin-layer chromatography. Short- and medium-chain fatty acids are absorbed directly into the blood via intestine capillaries and travel through the portal vein just as other absorbed nutrients do.

However, long-chain fatty acids are not directly released into the intestinal capillaries. Instead they are absorbed into the fatty walls of the intestine villi and reassemble again into triglycerides. The triglycerides are coated with cholesterol and protein protein coat into a compound called a chylomicron.

From within the cell, the chylomicron is released into a lymphatic capillary called a lacteal , which merges into larger lymphatic vessels. It is transported via the lymphatic system and the thoracic duct up to a location near the heart where the arteries and veins are larger. The thoracic duct empties the chylomicrons into the bloodstream via the left subclavian vein. At this point the chylomicrons can transport the triglycerides to tissues where they are stored or metabolized for energy.

When metabolized, fatty acids yield large quantities of ATP. Many cell types can use either glucose or fatty acids for this purpose. Fatty acids provided either by ingestion or by drawing on triglycerides stored in fatty tissues are distributed to cells to serve as a fuel for muscular contraction and general metabolism.

They are broken down to CO 2 and water by the intra-cellular mitochondria , releasing large amounts of energy, captured in the form of ATP through beta oxidation and the citric acid cycle. Fatty acids that are required for good health but cannot be made in sufficient quantity from other substrates, and therefore must be obtained from food, are called essential fatty acids. There are two series of essential fatty acids: one has a double bond three carbon atoms away from the methyl end; the other has a double bond six carbon atoms away from the methyl end.

Humans lack the ability to introduce double bonds in fatty acids beyond carbons 9 and 10, as counted from the carboxylic acid side. These fatty acids are widely distributed in plant oils. The human body has a limited ability to convert ALA into the longer-chain omega-3 fatty acids — eicosapentaenoic acid EPA and docosahexaenoic acid DHA , which can also be obtained from fish. Omega-3 and omega-6 fatty acids are biosynthetic precursors to endocannabinoids with antinociceptive , anxiolytic , and neurogenic properties.

They are taken in through the intestine in chylomicrons , but also exist in very low density lipoproteins VLDL and low density lipoproteins LDL after processing in the liver. In addition, when released from adipocytes , fatty acids exist in the blood as free fatty acids. It is proposed that the blend of fatty acids exuded by mammalian skin, together with lactic acid and pyruvic acid , is distinctive and enables animals with a keen sense of smell to differentiate individuals.

Fatty acids are mainly used in the production of soap , both for cosmetic purposes and, in the case of metallic soaps , as lubricants. Fatty acids are also converted, via their methyl esters, to fatty alcohols and fatty amines , which are precursors to surfactants, detergents, and lubricants. Esters of fatty acids with simpler alcohols such as methyl-, ethyl-, n-propyl-, isopropyl- and butyl esters are used as emollients in cosmetics and other personal care products and as synthetic lubricants.

From Wikipedia, the free encyclopedia. Main article: Saturated fat. Main article: Unsaturated fat. Main article: Fatty acid synthesis. Main article: Rancidification. Main article: Fatty acid metabolism. Main article: Essential fatty acid. Main article: Blood fatty acids. Fatty acid synthase Fatty acid synthesis Fatty aldehyde List of saturated fatty acids List of unsaturated fatty acids List of carboxylic acids Vegetable oil. Pure and Applied Chemistry. International Union of Pure and Applied Chemistry.

Retrieved Annales de Chimie , t. Recherches sur les corps gras d'origine animale. Levrault, Paris, Chronological history of lipid center. Cyberlipid Center. Last updated on 11 November De Boeck, Bruxelles. Lipids in Health and Disease. Nomenclature of Organic Chemistry.

Recommendations, ". European Journal of Biochemistry. Biochemistry 4th ed. New York: W. Freeman and Company.

The hydroxyl moiety in alcohols OH covalently bound to carbon have much different properties than the hydroxides in strong bases OH — anion bound to metal cation. Cis-oleic acid is the isomer which is found naturally in olive oil. Submit Feedback. When an hydroxyl group is bound to a carbon which is bound to only one other carbon, it is a primary alcohol. Fatty acids are usually produced industrially by the hydrolysis of triglycerides , with the removal of glycerol see oleochemicals. Pure and Applied Chemistry. Based on these reports, valproic acid is thought to be transported bidirectionally between blood and brain across the BBB via two distinct mechanisms, monocarboxylic acid-sensitive and medium-chain fatty acid-sensitive transporters, for efflux and uptake, respectively.

Fatty acid structures

Fatty acid structures

Fatty acid structures

Fatty acid structures

Fatty acid structures. Recent Posts

In the human body its generation depends on consumption of omega 3 essential fatty acids e. Herring acid Herring's, Nisinic acid is a 6,9,12,15,18,hexa unsaturated fatty acid with 24 carbon atoms. From Wikipedia, the free encyclopedia. Main article: Unsaturated fat. Asia Pacific Journal of Clinical Nutrition. Archived from the original on Retrieved Nutter, E. Lockhart and R. Harris Journal of the American Oil Chemists' Society. Picual" PDF. Food Chem. Lipid Technology. Gamma linolenic acid.

Gamma-linolenic acid metabolism and its roles in nutrition and medicine. Sorbilis Mart. Koch] cultivars". Food Chemistry. Canola Council of Canada. Retrieved May 6, Advanced nutrition and human metabolism. Smith, Jack L. Professor of nutrition ,, Carr, Timothy P. Seventh ed. Lipids : fatty acids. Palmitoleic Vaccenic Rumenic Paullinic 7,10,Eicosatrienoic Sapienic Gadoleic Categories : Fatty acids Chemistry-related lists Alkenoic acids.

Hidden categories: All articles with unsourced statements Articles with unsourced statements from January Namespaces Article Talk.

Views Read Edit View history. Languages Add links. By using this site, you agree to the Terms of Use and Privacy Policy. Flaxseeds, chia seeds, walnuts [1]. Seed oils of hemp, blackcurrant, corn gromwell [ citation needed ]. Related technology is used to convert vegetable oils into margarine. During partial hydrogenation, unsaturated fatty acids can be isomerized from cis to trans configuration.

In the Varrentrapp reaction certain unsaturated fatty acids are cleaved in molten alkali, a reaction which was, at one point of time, relevant to structure elucidation. Unsaturated fatty acids undergo a chemical change known as auto-oxidation. The process requires oxygen air and is accelerated by the presence of trace metals. Vegetable oils resist this process to a small degree because they contain antioxidants, such as tocopherol.

Fats and oils often are treated with chelating agents such as citric acid to remove the metal catalysts. Unsaturated fatty acids are susceptible to degradation by ozone. In chemical analysis, fatty acids are separated by gas chromatography of methyl esters; additionally, a separation of unsaturated isomers is possible by argentation thin-layer chromatography. Short- and medium-chain fatty acids are absorbed directly into the blood via intestine capillaries and travel through the portal vein just as other absorbed nutrients do.

However, long-chain fatty acids are not directly released into the intestinal capillaries. Instead they are absorbed into the fatty walls of the intestine villi and reassemble again into triglycerides. The triglycerides are coated with cholesterol and protein protein coat into a compound called a chylomicron. From within the cell, the chylomicron is released into a lymphatic capillary called a lacteal , which merges into larger lymphatic vessels.

It is transported via the lymphatic system and the thoracic duct up to a location near the heart where the arteries and veins are larger. The thoracic duct empties the chylomicrons into the bloodstream via the left subclavian vein. At this point the chylomicrons can transport the triglycerides to tissues where they are stored or metabolized for energy. When metabolized, fatty acids yield large quantities of ATP.

Many cell types can use either glucose or fatty acids for this purpose. Fatty acids provided either by ingestion or by drawing on triglycerides stored in fatty tissues are distributed to cells to serve as a fuel for muscular contraction and general metabolism. They are broken down to CO 2 and water by the intra-cellular mitochondria , releasing large amounts of energy, captured in the form of ATP through beta oxidation and the citric acid cycle.

Fatty acids that are required for good health but cannot be made in sufficient quantity from other substrates, and therefore must be obtained from food, are called essential fatty acids. There are two series of essential fatty acids: one has a double bond three carbon atoms away from the methyl end; the other has a double bond six carbon atoms away from the methyl end. Humans lack the ability to introduce double bonds in fatty acids beyond carbons 9 and 10, as counted from the carboxylic acid side.

These fatty acids are widely distributed in plant oils. The human body has a limited ability to convert ALA into the longer-chain omega-3 fatty acids — eicosapentaenoic acid EPA and docosahexaenoic acid DHA , which can also be obtained from fish.

Omega-3 and omega-6 fatty acids are biosynthetic precursors to endocannabinoids with antinociceptive , anxiolytic , and neurogenic properties. They are taken in through the intestine in chylomicrons , but also exist in very low density lipoproteins VLDL and low density lipoproteins LDL after processing in the liver.

In addition, when released from adipocytes , fatty acids exist in the blood as free fatty acids. It is proposed that the blend of fatty acids exuded by mammalian skin, together with lactic acid and pyruvic acid , is distinctive and enables animals with a keen sense of smell to differentiate individuals.

Fatty acids are mainly used in the production of soap , both for cosmetic purposes and, in the case of metallic soaps , as lubricants. Fatty acids are also converted, via their methyl esters, to fatty alcohols and fatty amines , which are precursors to surfactants, detergents, and lubricants. Esters of fatty acids with simpler alcohols such as methyl-, ethyl-, n-propyl-, isopropyl- and butyl esters are used as emollients in cosmetics and other personal care products and as synthetic lubricants.

From Wikipedia, the free encyclopedia. Main article: Saturated fat. Main article: Unsaturated fat. Main article: Fatty acid synthesis. Main article: Rancidification. Main article: Fatty acid metabolism. Main article: Essential fatty acid. Main article: Blood fatty acids. Fatty acid synthase Fatty acid synthesis Fatty aldehyde List of saturated fatty acids List of unsaturated fatty acids List of carboxylic acids Vegetable oil.

Pure and Applied Chemistry. International Union of Pure and Applied Chemistry. Retrieved Annales de Chimie , t. Recherches sur les corps gras d'origine animale. Levrault, Paris, Chronological history of lipid center. Cyberlipid Center. Last updated on 11 November De Boeck, Bruxelles. Lipids in Health and Disease.

Nomenclature of Organic Chemistry. Recommendations, ". European Journal of Biochemistry. Biochemistry 4th ed. New York: W. Freeman and Company. Hormone Research. Fundamentals of Biochemistry 2nd ed. John Wiley and Sons. Uptake of valproic acid was reduced in the presence of medium-chain fatty acids such as hexanoate, octanoate, and decanoate, but not propionate or butyrate, indicating that valproic acid is taken up into the brain via a transport system for medium-chain fatty acids, not short-chain fatty acids.

Based on these reports, valproic acid is thought to be transported bidirectionally between blood and brain across the BBB via two distinct mechanisms, monocarboxylic acid-sensitive and medium-chain fatty acid-sensitive transporters, for efflux and uptake, respectively.

Monocarboxylate transporters MCTs are known to mediate the transport of short chain monocarboxylates such as lactate, pyruvate and butyrate. MCT1 and MCT4 have also been associated with the transport of short chain fatty acids such as acetate and formate which are then metabolized in the astrocytes [78]. The Composition of Foods. Royal Society of Chemistry. Sundance Natural Foods.

Department of Agriculture. Archived from the original on Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. Journal of Chromatographic Science.

List of unsaturated fatty acids - Wikipedia

Branched-chain fatty acids are common constituents of the lipids of bacteria and animals, although they are rarely found other than as surface lipids of higher plants. Normally, the fatty acyl chain is saturated and the branch is a methyl-group, but unsaturated branched-chain fatty acids are found in marine animals, and branches other than methyl may be present in microbial lipids. In bacteria, their main function in membranes may be to increase the fluidity and lower the phase transition temperature of the lipid components as an alternative to the use of unsaturated fatty acids.

As they have mainly saturated aliphatic chains, branched-chain fatty acids are not vulnerable to attack by activated oxygen, and this may be an explanation for their occurrence on surfaces exposed to oxygen flux, such as skin and tear films. The following discussion is not intended to be comprehensive. In the latter, the methyl group has the S -configuration in general, reflecting its biosynthetic origin, but a small proportion of the R -enantiomer has been detected in soil bacteria, for example.

The common range of fatty acids of this kind with a single branch point only in a saturated chain are discussed in this section. They are common constituents of bacteria but are rarely found in other microorganisms. Via the food chain, they can be found in animal tissues, especially those of marine animals and ruminants. However, they can also be synthesised in animal tissues per se. In bacteria, their content and composition can often be used as taxonomic markers, and in the genus Bacillus , for example, some species have fatty acids with the iso -structure only, while others have the anteiso -structure.

These fatty acids are produced biosynthetically via the conventional mechanisms for the synthesis of saturated fatty acids in bacteria FAS II - see the appropriate web page , except that the nature of the primer molecules differ.

Thus, instead of acetyl-coA, 2-methylpropanyl-CoA derived from the amino acid valine is the primer for the biosynthesis of iso -branched fatty acids with an even number of carbon atoms odd-numbered chain , while 3-methylbutyryl-CoA derived from leucine is the primer for iso -fatty acids with an odd number of carbon atoms even-numbered chain.

For example, that in Escherichia coli cannot use them, but Bacillus subtilis has two FABH enzymes, which both prefer branched-chain substrates. Determination of the crystal structure of KAS III in the facultative anaerobe Propionibacterium acnes has shown that the enzyme has a cavity at the active site with a unique shape that favours branched-chain CoA precursors. Note: this sometimes leads to confusion in the informal nomenclatures that may be used in scientific publications.

For example, methyl-tetradecanoate acid is sometimes abbreviated to iso -methyl and sometimes iso -methyl; I prefer the former as it better reflects the systematic name, although many microbiologists tend to favour the latter. Because of the alternative route for iso -methyl formation and of alpha -oxidation processes, odd-numbered iso -methyl acids and even-numbered anteiso -methyl acids are also found in tissues.

Methyl branching tends to decrease the thickness of lipid bilayers while lowering chain ordering with the effect of enhancing the fluidity of membranes through the formation of kinks at the branching point. For example, during cold stress, the proportion of anteiso -branched fatty acids of many bacterial species tends to increase.

In contrast, thermophilic species have higher contents of iso -branched fatty acids that are often of a longer than average chain length. In animal tissues, the biosynthesis of these fatty acids de novo is normally a minor process and is believed to involve a similar mechanism to the above, but adipose tissue and especially brown adipose tissue but not liver or brain can be significant sources.

Catabolism of branched-chain amino acids in mitochondria generates the precursors, which are exported to the cytosol by adipose-specific expression of carnitine acetyltransferase. The fatty acid synthase then has sufficient flexibility to generate long-chain monomethyl branched fatty acids, although fatty acid elongases ELOVL can also contribute to the final content and composition.

On the other hand, biosynthesis of these acids can be an important process in some instances. Such fatty acids have been shown to inhibit the growth of breast cancer cells in vitro by inhibiting the synthesis of conventional fatty acids de novo. Triacylglycerols and wax esters containing isovaleric 3-methylbutyric acid and other branched-chain fatty acids are important constituents of the blubber and melon echo location oils of the toothed whales and dolphins, and an alkyldiacylglycerol containing this acid occurs in rabbit harderian gland.

Dolphins synthesise branched-chain fatty acids from leucine whereas beaked whales use valine as the precursor, but enzymes that can elongate isovaleric acid appear to be absent or limited in their activity. The free-living nematode Caenorhabditis elegans synthesises iso -methyl-tetradecanoic and hexadecanoic acids de novo and has been shown to be absolutely dependent on these for its growth and development.

Acyl-CoA synthetases guide the incorporation of branched-chain acids into specific phospholipids and thus regulate the phospholipid composition in the zygote. In higher plants, branched-chain components are only rarely reported from the seeds or green tissues, but methylhexadecanoic occurs at a level of 0. Neo fatty acids , which can be considered as having a terminal tertiary butyl group or with two iso-methyl groups, have been found in certain microorganisms, algae, plants and marine invertebrates.

Bacterial fatty acids: R -Methyloctadecanoic acid or tuberculostearic acid is a major component of the lipids of the tubercle bacillus and related bacterial species. Indeed its presence in bacterial cultures and sputum from patients is used in the diagnosis of tuberculosis. It is also found in Corynebacterium and some other bacterial species.

A number of fatty acids with a single methyl branch of this type have been isolated from other bacterial species.

For example, methylhexadecanoic and methyloctadecanoic acids are relatively common microbial constituents, and methylhexadecanoic acid and methyloctadecanoic acid are major components of the halotolerant bacterium Rubrobacter radiotolerans. The latter occurs in the aquatic bacterium Rhodococcus equi also. Mycobacterium phlei contains a range of methyl-branched fatty acids, including 8- and methylhexadecanoate, 9-methylheptadecanoate, methylnonadecanoate, methyleicosanoate, methyldocosanoate and methyltetracosanoate.

In mixed microbial populations such as those isolated from soil or other environmental samples, many different branched-chain fatty acids of this type may be found. Sponges and some other marine organisms contain methyl-branched fatty acids, but these are derived from microorganisms in their diet or that live in symbiosis with them.

For example, in addition to a number of iso - and anteiso -methyl-branched fatty acids, methyl, methyl, methyl, methyl and methyl were found in the lipids of the sponge Verongia aerophoba. Biosynthesis of branched-chain fatty acids of this type involves methylation at the double bond of a monoenoic acid such as oleic or cis -vaccenic acid esterified as a component of a phospholipid, with S -adenosylmethionine as the methyl donor. The resulting R methylene-octadecanoyl residue is reduced to the methyl compound with NADPH as the cofactor; the intermediate methylene-octadecanoic acid has been isolated from a Corynebacterium.

A related mechanism is used for biosynthesis of cyclopropane fatty acids in bacteria. Relatively high proportions of propionic acid as opposed to acetic and butyric are produced by the rumen microorganisms under this regime, and this metabolite is in turn converted to methylmalonyl-CoA, presumably by the promiscuous reaction of acetyl-CoA carboxylase on propionyl-CoA ethyl malonate can be produced similarly from butyryl-CoA. A consequence of this mechanism is that the methyl groups are all in the even-numbered positions, and are distributed randomly in fatty acids of varying chain-lengths.

In other species, the enzyme ECHDC1 is has a repair function that serves to prevent the formation of the branched-chain intermediates. Some such methyl-branched fatty acids occur in a few disparate tissues in the animal kingdom. Perhaps the best known is the uropygial preen gland of birds that secretes a waxy material that serves to waterproof the feathers. While the precise composition of this varies from species to species, all are characterized by high concentrations of branched-chain fatty acids and alcohols.

Usually the branch is a methyl group, but ethyl and propyl branches are also known. Di-, tri- and tetramethyl-branched fatty acids are also present. A common pattern is to find series such as 2,4-, 2,6-, 2,8- and 4,6-dimethyl, and so forth, with 2,4,6-, 2,4,8- and 2,6,8-trimethyl, and 2,4,6,8-tetramethyl fatty acids. However, the preen gland of the barn owl contains 3-methyl- and 3,5-, 3,7-, 3,9-, 3,, 3,, and 3,dimethyl-branched fatty acids.

As an example, the composition of the fatty acids in the uropygial gland of the fulmar is listed in Table 1. Much remains to be learned of the mechanism of biosynthesis of these fatty acids, but again it appears that a high proportion at least is produced via methylmalonyl-CoA instead of malonyl-CoA for chain-elongation and to insert the methyl group. A further interesting example is Vernix caseosa , the waxy skin secretion that covers newborn babies.

These fatty acids are also found in the intestines of new-born, where they arise from lipid-laden vernix caseosa particles suspended in amniotic fluid; there is a suggestion that they may inhibit microbial attack.

Multi-branched from bacteria: Non-isoprenoid dimethyl-branched fatty acids are frequently reported from bacteria. For example, 4,9-dimethyl, 4, and 4,dimethyl, and 4,dimethyl acids, with 2, and 2,dimethyl acids were identified in a halophilic Bacillus sp. Multi-branched fatty acids with the methyl branches in positions 2-, 4-, 6- and 8- are present in certain Mycobacteria.

Dimethyl fatty acids are occasionally reported from sponges, where they are presumed to be derived from bacteria in the food chain or that are symbiotic, e. Dimethyl, dicarboxylic acids termed diabolic acids , were first reported from rumen bacteria, such as Butyrivibrio fibrisolvens , but related fatty acids have since been found in many species from the genus Acidobacteria , especially.

Diabolic acid per se is 15,dimethyltriacontanedioic acid, while iso -diabolic acid is 13,dimethyloctacosanedioic acid. Some Acidobacteria produce iso -diabolic acid with a further methyl group in position 5, i.

Similar fatty acids occur in some plant waxes. Diabolic acid is formed biosynthetically by a tail to tail joining of two molecules of palmitic acid with no loss of hydrogen from positions 14 and Each of the carboxyl groups can link to a glycerol moiety as part of a highly complex lipid that can span a membrane bilayer, often together with analogous ether lipids in Acidobacteria especially.

This is believed to provide greater stability to membranes under adverse pH conditions or at higher temperatures. These differ from the corresponding lipids in the Archaea in the stereochemistry of the glycerol moiety, i. A number of isoprenoid fatty acids that are derived from the metabolism of phytol 3,7,11,tetramethylhexadec- trans enol , the aliphatic alcohol moiety of chlorophyll, occur naturally in animal tissues.

Phytanic acid occurs in tissues as a racemic mixture of 3 R ,7 R ,11 R ,15 - and 3 S ,7 R ,11 R ,15 -tetramethylhexadecanoic acids. Normally, these fatty acids occur at low levels only in tissues, with the concentrations being highest in herbivores.

However, much higher concentrations can occur on occasion. Dietary chlorophyll cannot be hydrolysed to phytol in the digestive system of humans, but rumen microorganisms can accomplish this.

In the tissues of ruminant animals, phytanic acid is formed by oxidation of phytol first to phytenal and then to phytenic acid with a double bond in position 2 and only encountered in tissues under artificial feeding conditions , followed by reduction. Presumably, phytanic acid is formed in an analogous manner in fish and can thence enter the human food chain also. Some omega -oxidation occurs also with 3-methyladipic acid as an end-product. In humans, several inborn metabolic errors in the degradation of phytanic and pristanic acids have been described that lead to an accumulation of these acids in tissues and body fluids.

In contrast, there are suggestions that phytanic and pristanic acids may an number of beneficial influences towards heath that include protective effects against the metabolic syndrome, induction of the differentiation of brown adipocytes, and inhibition of breast, colon and other cancers. They are signalling molecules that function by regulating the expression of those genes that affect the catabolism of lipids.

In a sense, they are regulators of their own degradation. Also, phytanic acid functions also as a regulator of aspects of glucose and retinoic acid metabolism. Similarly, retinoic acid , an isoprenoid acid derived from vitamin A, is an important regulator of genes involved in cell growth and differentiation via distinct transport proteins and nuclear receptors, but it has its own web page.

In contrast to phytanic acid, it is not found esterified to mainstream lipids in tissues. Monounsaturated methyl branched-chain fatty acids have been detected in bacteria and marine animals. For example, one of the first acids of this type to be described was 7-methylhexadecenoic acid from lipids of the ocean sunfish Mola mola , while 7-methyl and 7-methylhexadecenoic acids were later found in sponges. It is possible that the primary origin of these fatty acids is in bacteria, as these can contain many comparable fatty acids, for example in Bacillus cereus , B.

Many different demospongic acids, i. Unusual multibranched polyunsaturated and very-long-chain fatty acids have been located in slime moulds and freshwater sponges from Israel, including 2 E ,4 E ,7 S ,8 E 10 E 12 E 14 S -7,9,13,tetramethyl-7,dihydroxy-2,4,8,10,12,octadecahexaenoic acid from seven different species of myxomycetes.

Branched-chain fatty acids are not common in plants, but small amounts of methyl- cis octadecenoic and methyl- cis -9, cis octadecadienoic acids have been found in wood and seeds of certain Gymnosperm species. They are major components of the lipids in cell walls of Mycobacteria and related species, including the genera Mycobacterium , Nocardia , Rhodococcus and Corynebacterium , but because of its pathogenicity, those of M.

The main unit of these fatty acids is termed a "meromycolic chain", and depending on species, it can contain a variety of functional groups, including double bonds of both the cis- and trans -configurations but when the latter, they also possess an adjacent methyl branch and cyclopropane rings, which can also be of the cis - and trans -configurations. In addition, they can contain hydroxy, methoxy-, epoxy- and keto groups of distinct stereochemistry, which are also adjacent to a methyl branch normally.

The 2 R -,3 R -stereochemistry of the substituents at positions 2 and 3 is conserved in all genera. The secondary or alpha-branched unit commonly consists of a C 22 to C 26 unsubstituted alkyl chain. The least polar mycolic acids, often termed alpha-mycolic acids, contain carbon atoms and generally two double bonds of the cis - or trans -configuration or two cis -cyclopropyl groups located in the meromycolic chain; some may contain further double bonds, e.

Cyclopropyl rings in the alpha-mycolates tend to have the cis -configuration.

Fatty acid structures