Palmitoleate oxidation

Additionally, it should be observed that the thermal oxidability and oxidative polymerization of the unsaturated fatty acids follows the trend linolenic > linoleic > oleic > > palmitoleic (Martinenghi, 1963). The oxidation involves, as first step, the abstraction of a hydrogen atom in allylic position to the double bonds. Certainly, this process is favoured in the case of fatty acids with two or more unconjugated double bonds where the formation of a free radical by allylic hydrogen abstraction leads quite necessarily to double bonds slippage with formation of conjugated double bonds ... 

Palmitate and stearate serve as precursors of the two most common monounsaturated fatty acids of animal tissues palmitoleate, 16 1(A9), and oleate, 18 1(A9) both of these fatty acids have a single cis double bond between C-9 and C-10 (see Table 10-1). The double bond is introduced into the fatty acid chain by an oxidative reaction catalyzed by fatty acyl-CoA desatu-rase (Fig. 21-13), a mixed-function oxidase (Box 21-1). Two different substrates, the fatty acid and NADH or NADPH, simultaneously undergo two-electron... 

Consider the oxidation of palmitoleate. This Cjg unsaturated fatty acid, which has one double bond between C-9 and C-10, is activated and transported across the inner mitochondrial membrane in the same way as saturated fatty acids. Palmitoleoyl CoA then undergoes three cycles of degradation, which are carried out by the same enzymes as in the oxidation of saturated fatty acids. However, the cis-A 3-enoyl CoA formed in the third round is not a substrate for acyl CoA dehydrogenase. The presence of a double bond between C-3 and C-4 prevents the formation of another double bond between C-2 and C-3. This impasse is resolved by a new reaction that shifts the position and configuration of the cis-A double bond. An isomerase converts this double bond into a trans- A double bond. The subsequent reactions are those of the saturated fatty acid oxidation pathway, in which the trans- A 2-enoyl CoA is a regular substrate. 

A variety of unsaturated fatty acids can be formed from oleate by a combination of elongation and desaturation reactions. For example, oleate can be elongated to a 20 1 cis-A fatty acid. Alternatively, a second double bond can be inserted to yield an 18 2 cis-A, A fatty acid. Similarly, palmitate (16 0) can be oxidized to palmitoleate (16 1 cis-A ), which can then be elongated to cA-vaccenate (18 1 cis-A H). 

A. The 16-carbon, fully saturated fatty add, palmitate (16 0), is the product of the fatty acid synthase complex. It may be elongated by two carbons to form stearic add (18 0), or it may be oxidized to form palmitoleic acid (16 1,A9). Stearate can be oxidized to oleic acid (18 1,A ). Arachidonic acid (20 4,A5,8 11 14) can be synthesized from the essential fatty acid linoleate (18 2,A9 12). It cannot be produced from palmitate. Fatty acids synthesized in the liver are converted to triacylglycerols, packaged in VLDL, and secreted into the blood. 

The levels of palmitic acid, palmitoleic acid, stearic acid and oleic acid increased in both groups, after 4 h of copper-oxidation. While concentrations of cholesteryl oleate, cholesteryl linoleate, cholesteryl arachidonate and cholesteryl docosahexanoate were reduced, following copper stimulated oxidation, in both groups [85]. 

Desaturation of fatty acids involves a process that requires molecular oxygen (O2), NADH, and cytochrome dj. The reaction, which occurs in the endoplasmic reticulum, results in the oxidation of both the fatty acid and NADH (Fig. 33.18). The most common desaturation reactions involve the placement of a double bond between carbons 9 and 10 in the conversion of palmitic acid to palmitoleic acid (16 1, A ) and the conversion of stearic acid to oleic acid (18 1, A ). Other positions that can be desaturated in humans include carbons 4, 5, and 6. 

Problem 19.20. Write the equation for air oxidation of palmitoleic acid. 

The annual production is about 0.7 million tonnes. The seed has 40%-60% oil with almost equal levels of oleic acid (range 35%-54%, average 46%), linoleic acid (range 39%-59%, average 46%), palmitic acid (7%-12%), palmitoleic acid (trace to 0.5%), stearic acid (3.5%-6%), linolenic acid (trace to 1%), and eicosenoic acid (trace to 1%). The oil contains sesamin (0.5%-l.l%) and sesamo-lin (0.3%-0.6%) and has high oxidative stability due to the presence of natural antioxidants. ... 

Strain D S5 oxidized unsaturated but not saturated fatty acids. The relative activities were in the following order oleic > palmitoleic > arachidonic > linoleic > linolenic > y-linolenic > myristoleic acids. 

Ammonium citrate dibasic Barium fluoride Barium nitrate Bismuth Calcium fluoride Calcium titanate Carbon Cobalt sulfate (ous) Gold Hydrogen peroxide y-Linolenic acid Niobium oxide Nitrogen Palmitoleic acid Polyester carbonate resin Selenium Sodium chlorite Strontium titanate electronics applies. 

Palmitoleic (13) and similar acids may arise by p-oxidation of oleic acid (3). 

Another study, conducted by Demizieux et al. (42), dealt with the mitochondrial oxidizability of CIA. c9,tl 1- and rlO,cl2-ClA were compared to LA and palmitoleic acid as substrates for total fatty acid oxidation and for the enzymatic steps required for the entry of fatty acids into rat liver mitochondria. Both CLA isomers were shown to be oxidized to a marked lesser extent than LA and to be capable of accumulating inside the mitochondrial matrix and of interfering with the oxidation of usual fatty acids at a step close to the beginning of the P-oxidative cycle. 

In addition to even-numbered, long-chain fatty acids, the brain also contains odd-numbered fatty acids, which may contain one or more unsaturated bonds. The co isomers are related to palmitoleate and are therefore assumed to be derived from palmitoleate by elongation and a-oxidation. The precursors of the and co isomers are unknown. 

Arachidonic, palmitoleic, linoleic, eicosatrienoic, oleic, palmitic, and stearic acids were extracted fiom venous blood and baseline resolved as their 4-bromomethyl-7-methoxycouramrin derivatives in 40 min on a C g column (2. = 325 nm, ex 398 nm, em) using an 85/15 acetonitiile/water mobile phase [1064]. Working curves were generated for concentrations of 50-500 pmol/L. Detection limits of 10pmol/L (S/N = 3) were reported. Samples were diluted in solutions containing BHT to prevent oxidation of the acids. 

Fig. 1. Effect of propylthiouracil and thyroxine [ administration compared to controls LZ] on the oxidative desaturation of l-l c linoleic acid to y-linolenic acid (18 2->18 3) and palmitic acid to palmitoleic acid (16 0- 16 1). Results are means of analysis of 5 animals (each analysis was performed in duplicate). Vertical lines represents 1 SEM. Results corresponding to thyroxine-treated rats are significantly different from the controls (p<0.001).

Octamethylene dibromide 2968 Palmitoleic acid 5757 Perfluoropropylene oxide 10424... 

The Coleoptera (beetles) contains about 300,000 species and are very varied in form, diet and habitat. Equally they have very different kinds of pheromones and defensive secretions, many of them derived from fatty acids. The bean weevil Acanthoscelides obtectus uses an unusual allenic methyl ester (Figure 3.25). Its biosynthesis has not yet been investigated. Allenes are an unusual example of chirality. Anomala cuprea, a chafer grub produces two lactone sex attractants, derived from the unsaturated acids oleic and palmitoleic acids (Figure 3.25). Both are shortened by the loss of two acetic acid units, then oxidized (stereospecifically) at the allylic position and cyclized to the pheromone. 

The conversions of 1-C -palmitic acid to l-C -palmitoleic acid and stearic acid to oleic acid were effected aerobically in the presence of CoA, ATP, TPNH, and Mg++. Oxygen could not be replaced by electron acceptors such as methylene blue, FAD, or ferricyanide. When palmityl-CoA was used as substrate, desaturation required only the particulate fraction of yeast homogenate, TPNH, and oxygen. The reaction was stimulated by cyanide ions, inhibited by cytochrome c, but not by catalase. These properties are typical for hydroxylases of the mixed function transferase category (Mason, 1957). Proof of the location of the double bond between C-9 and C-10 was established by permanganate-periodate oxidation of palmitoleic acid and the isolation of azelaic acid. 

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