April 20, 2011
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fatty acids (fatty acid), is at one end with a carboxyl group of long chain aliphatic hydrocarbon, organic matter, the general formula is C (n) H (2n 1) COOH, the primary fatty acid is a colorless liquid with a pungent odor, higher fatty acids are waxy solids, no obvious smell of the breath. Fatty acid is the most simple kind of fat, it is a lot more vast and complex lipid composition. Adequate supply of fatty acids in the case of oxygen, oxidized decomposed into CO2 and H2O, acquitted a large number of energy, which fatty acids are important energy source of the body.
3 fatty acids, fatty acid-fatty acids is constructed from carbon, hydrogen, oxygen composed of three elements of a class of compounds, neutral fats, phospholipids and glycolipids of the main ingredients. Fatty acids according to the different carbon chain lengths can also be divided into short-chain fatty acids (short chain fatty acids, SCFA), the carbon chain of less than 6 carbon atoms, also known as volatile fatty acids (volatile fatty acids, VFA) ; medium-chain fatty acids (Midchain fatty acids, MCFA), refers to the carbon chain of 6-12 carbon atoms of fatty acids, the main ingredient is bitter (C8) and capric acid (C10); long-chain fatty acids (Longchain fatty acids, LCFA) , the number of carbon atoms on the carbon chain greater than 12. Individual fatty acids the food contains mostly long chain fatty acids. Fatty acids based on saturated and unsaturated hydrocarbon chain can be divided into three categories, namely: saturated fatty acids (saturated fatty acids, SFA), unsaturated hydrocarbon is no key; monounsaturated fatty acids (Monounsaturated fatty acids, MUFA), the unsaturated hydrocarbon chain with a key; polyunsaturated fat (Polyunsaturated fatty acids, PUFA), the hydrocarbon chain has two or more unsaturated bonds. Rich in monounsaturated fatty acids and polyunsaturated fatty acid composition of the fat is liquid at room temperature, mostly vegetable oils such as peanut oil, corn oil, soybean oil, nut oil (A glycerol), rapeseed oil. Saturated fatty acid composition of fat-based solid state at room temperature, mostly animal fats such as butter, suet, lard, etc. But there are exceptions, such as fish oil, although animal fat, but it is rich in polyunsaturated fatty acids, such as carbon-20 5 acid (EPA) and 22 C 6 acid (DHA), which is liquid at room temperature. Classification Introduction about 40 different artificial boundary fatty acids, lipids are crucial ingredients. Depends on many physical characteristics of lipid fatty acid saturation and carbon chain length, which for the body to receive, use only the even-numbered carbon atom fatty acids. Fatty acids classified according to their different structures, but also from a nutritional point of view, according to their nutritional value for human classification. Different categories according to carbon chain length. It can be divided into short-chain (with 4 to 6 carbon atoms) fatty acids; in the chain (with 8 to 14 carbon atoms) fatty acids; long-chain (with 16 to 18 carbon atoms) and long chain fatty acids (including 20 or more carbon atoms) fatty acids in four categories. The human body contains mostly long-chain fatty acid composition of lipids. It is classified according to saturation can be divided into saturated and unsaturated fatty acids into two categories. Of unsaturated fatty acids, then the level of unsaturated fatty acids into monounsaturated and polyunsaturated fatty acids. Monounsaturated fatty acids, the molecular structure of only one double bond; polyunsaturated fatty acids, the molecular structure containing two or more double bonds. Followed by the development of nutritional science, invention where the double bond position to influence the nutritional value of fatty acids, so now often classified according to their double bond position. Fatty acid double bond position from both ends of the molecular structure of the beginning of the first carbon atom number. Often from the fatty acids present, and the emergence of its first double bond position to distinguish the different family known as the ω-3, ω-6 family, ω-9 unsaturated fatty acids such as family, this kind of classification in nutrition and more applied significance. Classified according to nutritional point of view of non-essential fatty acids can be synthesized by the body, not dependent on food supply of fatty acids, which includes saturated fatty acids and some monounsaturated fatty acids. And essential fatty acids necessary for human health and life, but my body can not synthesize and must rely on food supply, they are unsaturated fatty acids, belongs to the ω-3 and ω-6 family of polyunsaturated fatty acid family. Previously only discouraged ω-6 family of linoleic acid, essential fatty acids that are present only match to determine the essential fatty acids linoleic acid. They can be changed from linoleic acid, linoleic acid supply surplus in the two fatty acids that, when not to lack. Since the discovery of ω-3 family of fatty acids since its physiological effects and the importance of nutrition is the more people adopt the more valued. ω-3 family of fatty acids including linolenic acid and some polyunsaturated fatty acids, there are many fish in deep sea fish oil, its physiological function and role of nutrition to be developed and further research. Essential fatty acids necessary not only for nutrition, and child growth and development and growth and health-related, more fat, the role of prevention and treatment of coronary heart disease and other medical treatment, and with the mental development, memory and other physiological functions must be related. Composition of saturated fatty acids (saturated fatty acid): does not contain-C = C-double bond of the fatty acids. Unsaturated fatty acids (unsaturated fatty acid): contains at least-C = C-double bond of the fatty acids. Essential fatty acids (essential fatty acid): required to maintain normal growth of mammals, and animals and can not synthesize fatty acids such as linoleic acid, linolenic acid. Three acyl glycosides oil (triacylglycerol): also known as triglycerides. One kind of contain three acyl glycerol esters. Fat and oil is a mixture of three diacylglycerol. Phospholipid (phospholipid): lipid composition containing phosphoric acid. Such as lecithin, cephalin. Sphingolipids (sphingolipid): a class of sphingosine skeleton gender fat, with one end connected to a long fatty acid, the other side of a polarity and alcohol. Sphingolipids include sphingomyelin, cephalin, and gangliosides, normally present in the cell membrane of plants and animals, especially in the central nervous system tissue content rich. Sphingomyelin (sphingomyelin): a by ceramide convergence on C-1 hydroxyl Maori seeking choline phosphate (or phosphoric acid acetamide) the formation of sphingolipids. Sphingomyelin exists in most mammalian plasma membrane of animal cells is the main component of myelin. Lecithin (lecithin): namely, phosphatidylcholine (PC), is phosphatidyl choline to form complexes with. Brain phospholipids (cephalin): namely, phosphatidylethanolamine (PE), is phosphatidyl ethanolamine with the formation of complexes. Liposomes (liposome): the phase space by encircling the phospholipid layer of water formed vesicles (vesicles). Fatty acids from carbon, hydrogen, oxygen composed of three elements of a class of compounds, neutral fats, phospholipids and glycolipids of the main component, mbt marketing communications. According to the molecular structure of fatty acid carbon chain length into short chain fatty acids (carbon chain in less than six carbon atoms), medium-chain fatty acids (carbon chain in the 6 to 12 carbon atoms) and long-chain fatty acids (carbon chain of carbon atoms more than 12) categories. Fatty acids contained in foods in general are mostly long-chain fatty acids. According to the carbon chain, the number of double bonds between carbon atoms in the fatty acids can be divided into monounsaturated fatty acids (including one double bond), polyunsaturated fatty acids (including one or more double bonds) and saturated fatty acids (without double bonds) three categories. Rich in monounsaturated fatty acids and polyunsaturated fatty acid composition of the fat is liquid at room temperature, mostly vegetable oils such as peanut oil, corn oil, soybean oil, rapeseed oil. Saturated fatty acid composition of fat-based solid state at room temperature, mostly animal fats such as butter, suet, lard, etc. There are exceptions, of course, animal fats such as fish oil, but it is rich in polyunsaturated fatty acids, such as carbon-20 5 acid (EPA) and 22 C 6 acid (DHA), so is liquid at room temperature. The table below are some common oil fatty acids. Functional fatty acid (fatty acid) carboxylic acids with long hydrocarbon chains. Usually in the form of esters for a variety of lipid components to form free fatty acids are common in the natural world, the most common fatty acids in the table below. Most fatty acids contain an even number of carbon atoms, because they are usually from 2 carbon unit biosynthesis. Senior animals and plants the most abundant fatty acids containing 16 or 18 carbon atoms, such as palmitic acid (palmitic acid), oleic acid, linoleic acid and stearic acid. Plants and animals than half of the lipid fatty acids unsaturated fatty acids containing double bonds, and often more than double bonds of unsaturated fatty acids. Few bacterial fatty acid double bonds but often hydroxylation, or contain branched chain or cyclic structure containing cyclopropane. Some vegetable oils and waxes contain unusual fatty acids. Unsaturated fatty acids must have a double bond at C (9) and C (10) between the (starting from the carboxyl carbon atoms). Almost always fatty acid cis-double bond geometry, which makes the unsaturated fatty acid hydrocarbon chain of about 30 ° of the twists and turns, annoyance when they accumulate to effectively fill the space, each response results in reduced van der Waals force, so that the melting point of fatty acids With the growth of its lower degree of unsaturation. Lipid mobility with the unsaturated fatty acids increase, the scene of the film properties have a major impact. Saturated fatty acids are very flexible molecules, in practice filled each C-C bond can rotate absolutely freely, and thus a wide scope of some conformation. However, the stretch of sufficient energy conformation with the smallest, most stable; because the conformation of the methylene adjacent to steric hindrance between the minimum. And most of the substances, the melting point of saturated fatty acids with the molecular weight increases. Animals can synthesize saturated fatty acids and linoleic acid required with only one double bond of these unsaturated fatty acids, containing two or more double bonds than double bonds of fatty acids must be obtained from plants, so the latter said for the essential fatty acids, linolenic acid and linoleic acid in which the most important. Arachidonic acid from linoleic acid generation. Arachidonic acid is the precursor of most prostaglandins, prostaglandin can regulate cell function is hormone-like substances. Fatty acids can be used for the production of styrene-butadiene rubber emulsifiers and other surfactant, smooth agent, brightener; can be used to produce advanced soap, transparent soap, stearic acid and a variety of active agents next to the name of the body. Used oil fatty acids monounsaturated fat saturated fat, fatty acids polyunsaturated fatty acids of soybean oil peanut oil 142 561 145 036 152 461 Corn oil low erucic acid rapeseed oil sunflower oil 66 232 121 969 281 854 Cotton seed oil and sesame oil 154 144 513 910 palm oil, pig fat, tallow 384 814 51 427 suet 543 610 314 821 chicken fat fish oil 282 349 β-oxidation of fatty acids in the liver and muscle foreword for fatty acid oxidation is the most lively organization, its main oxidized form of β-oxidation. This process can be divided into activation, transfer, β-oxidation of three stages. Fatty acid and glucose activation of the same fatty acids are also added before the first metabolic activation. The activation form thioester – fatty acyl CoA, fatty acid activation of the enzyme-catalyzed acyl-CoA synthetase (acyl CoA synthetase). Activated acyl-CoA generated polarity increased, soluble in water; molecules in high-energy bond, the nature of activity; is enzyme specific substrate, the enzyme affinity with a large, making it easier to participate in reactions. ? Acyl-CoA synthase kinase, also known as sulfur, scattered in the cytoplasm, mitochondria and endoplasmic reticulum. Sulfur in the cytoplasm in the short-chain fatty acid kinase catalytic activation; activity on the endoplasmic reticulum of long-chain fatty acids, generating acyl CoA, then backward into the endoplasmic reticulum for triglyceride synthesis; while the activity of the mitochondrial membrane long-chain acyl-CoA, into the mitochondria into the β-oxidation. Acyl CoA into the mitochondrial fatty acid β-oxidation catalytic enzymes in the mitochondrial matrix, but not long-chain acyl-CoA through the mitochondrial membrane free to enter the mitochondrial matrix requires the carrier transport, the carrier is carnitine (carnitine) , that is, 3 – hydroxy -4– top three amino acid. Long-chain fatty acyl CoA and carnitine reaction of coenzyme A and acyl-carnitine, and fatty acyl carnitine 3 – hydroxy-connected by ester bond. The enzyme catalyzed the reaction of carnitine acyl transferase (carnitine acyl transferase). Both internal and external sides of the inner mitochondrial membrane of this enzyme, Department of isozymes, discounted mbt tariki shoes, called the separation of carnitine acyl transferase I and carnitine acyl transferase Ⅱ. Ⅰ the cytoplasm of the enzyme acyl-CoA into fatty acyl coenzyme A and carnitine, the latter into the mitochondrial inner membrane. Located in the inner mitochondrial membrane enzyme fatty acyl carnitine Ⅱ and make into carnitine and acyl-CoA, carnitine carrier from the new display its function, while acyl CoA into the mitochondrial matrix, a fatty acid β-oxidation enzymes the substrate. Long-chain acyl-CoA into the mitochondria by the carnitine acyl-speed transferase Ⅰ and Ⅱ enzyme regulation of malonyl-CoA by the enzyme inhibition Ⅰ, Ⅱ enzyme inhibition by insulin. Malonyl-CoA is the raw material for synthesis of fatty acids, insulin by inducing the synthesis of acetyl-CoA carboxylase to malonyl-CoA concentration, and thus restrain the enzyme Ⅰ. Insulin can be seen on carnitine acyl transferase Ⅰ and Ⅱ enzyme inhibition directly or indirectly made use of. Hunger or fasting insulin secretion, carnitine acyl transferase Ⅰ and Ⅱ enzyme activity increased, the transfer of long chain fatty acids into the mitochondria for energy. β-oxidation reaction in acyl-CoA into the mitochondrial matrix β-oxidation to go through four-step reaction, dehydrogenation, water, and then dehydrogenation and thiolase, acetyl-CoA and generates a small part of two new carbon grease acyl CoA. The first step dehydrogenation (dehydrogenation) reaction from the acyl-CoA dehydrogenase activation, cofactor as FAD, acyl-CoA in the α and β carbon atoms of the hydrogen atoms off a trans double bond is generated with α, β-ene fatty acyl coenzyme A. The second step water (hydration) reaction by the catalytic enoyl CoA hydratase, has L-configuration to generate the β-hydroxy acyl-CoA. The third step is the dehydrogenation reaction of β-hydroxy fatty acyl CoA de-yee enzyme (coenzyme to NAD) catalyst, β-hydroxy fatty acyl CoA dehydrogenation β keto acyl-CoA. Step thiolase (thiolysis) reaction from the β-keto thiolase catalysis, β-keto ester-CoA in the α and β chain scission between carbon atoms, with part of acetyl-CoA and coenzyme A to generate a small two carbon atoms The acyl CoA. The four-step reaction with the TCA cycle via fumarate by succinic acid, malic acid oxaloacetate generated similar to the process, only the fourth β-oxidation thiolase step reaction, and oxaloacetate next step in the condensation reaction with acetyl-CoA produce citric acid. Long-chain acyl-CoA by the above iteration, to reduce the carbon chain of two carbon atoms to produce a part of acetyl CoA, repeatedly repeat the cycle, will gradually produce acetyl CoA. As can be seen from the above fatty acid β-oxidation process has the following characteristics. First, to generate acyl-fatty acid activation of CoA, which is an energy-consuming process. , The short-chain fatty acids do not need to pull the carrier can directly enter the mitochondria, while the need for long-chain acyl-CoA carnitine transporter. β-oxidation within the mitochondria, red blood cells can not therefore not of mitochondrial oxidation of fatty acids for energy. β-oxidation in the process of FADH2 and NADH H generated by the respiratory chain of these hydrogen transfer to oxygen to produce water, oxygen required to participate, the oxidation of acetyl-CoA also requires oxygen. Therefore, β-oxidation process is relatively aerobic, mbt discount. Fatty acid β-oxidation of the physiological significance of fatty acid β-oxidation of fatty acids in the body break down the main avenues, fatty acid oxidation can supply the body needs a lot of energy to sixteen carbon atoms, saturated fatty acid palmitic acid, for example, the β-oxidation The overall reaction is: CH3 (CH2) 14COSCoA 7NAD 7FAD HSCoA 7H2O – → 8CH3COSCoA 7FADH2 7NADH 7H?? 7 FADH2 molecules provide 7 × 2 = 14 molecules ATP, 7 molecules NADH H provides 7 × 3 = 21 molecules ATP, 8 molecule acetyl CoA oxidation to provide a full 8 × 12 = 96 molecules of ATP, so one mole of palmitic acid completely oxidized to CO2 and H2O, the supply of a total of 131 mole ATP. The activation of palmitic acid molar consumption of 2 ATP, so one mole of palmitic acid completely oxidized to generate a net 129 mole ATP. Fatty acid oxidation energy released when about 40% of the body using synthetic high-energy compounds, and the remaining 60% in the form of heat release, heat effect of 40%, to clarify the body can be very effective day with the energy provided by fatty acid oxidation. Fatty acids, fatty acid β-oxidation is the transformation process, the body needs different fatty acid chain length, through β-oxidation of long chain fatty acids may be the right degree of reform and growth of fatty acids required for metabolism. Fatty acid β-oxidation of acetyl-CoA generated is a very important intermediate compounds, in addition to acetyl-CoA into the citric acid cycle oxidation for energy, but still many of the major compounds, synthetic materials, such as ketone bodies, cholesterol and steroid compounds . Oxidation of fatty acids in the form of a special acid oxidation of odd carbon fatty acids, generated by β-oxidation of acetyl-CoA but also generate foreign member of propionyl CoA, certain amino acids such as isoleucine, methionine and threonine catabolism in C-CoA formation, bile acid generation process also generates propionyl-CoA. After propionyl CoA carboxylase reaction and intramolecular rearrangement, can be transformed to generate succinyl-CoA, further oxidation and decomposition, can also be generated by different sugar oxaloacetate, see the right reaction. 2α-oxidation of fatty acids by the microsomal monooxygenase and decarboxylase catalyzed α-hydroxy fatty acids to generate carbon atoms or less a process called fatty acid α-oxidation of fatty acids. Long-chain fatty acids catalyzed by the monooxygenase by ascorbic acid, or folate as a hydrogen donor for the O2 and Fe2 in the participation of α-hydroxy fatty acids generated, which is cerebroside and sulfur important component of fat, α-hydroxy fatty acid oxidation continued decarboxylation to generate the odd carbon fatty acids. impaired α-oxidation of phytanic acid can not be oxidized (phytanic acid, 3,7,11,15 – tetramethyl-hexadecanoic acid). 3ω-ω-oxidation of fatty acid oxidation in liver microsomes was carried out by the monooxygenase-catalyzed. First, fatty acid ω-hydroxylation of carbon atoms generated ω-carboxylic fatty acids, fatty acids, aldehydes generated via ω α, ω-dicarboxylic acid, and then the α-ω-end side or activation of β-oxidation into the mitochondria into the last generation amber acyl CoA. Oxidation of unsaturated fatty acids (unsaturated fatty acid) the body about 1 / 2 or more fatty acids are unsaturated fatty acids, foods also contain unsaturated fatty acids. These unsaturated fatty acids are cis-double bond, and they entered the activation of β-oxidation, the resulting 3 – cis-enoyl-CoA, then need isomerase-catalyzed cis-3 trans-2 to generate 2 – Anti- enoyl-CoA for further reaction. 2– anti-enoyl-CoA by adding water to generate D-β-hydroxy acyl-CoA, β-hydroxybutyrate needed difference to the fat-CoA isomerase catalysis, to the D-configuration change to L-configuration, in order to further deoxygenation reaction (only L-β-hydroxy acyl-CoA β-hydroxybutyrate talent as acyl CoA dehydrogenase substrate). Complete oxidation of unsaturated fatty acids to CO2 and H2O to provide the ATP same number of carbon atoms less than the saturated fatty acids, mbt outlet store punctuation. Introduction and utilization of ketone formation ketones (acetone bodies) is a normal fatty acid catabolism in the liver specific intermediate product generated, including acetylsalicylic acid (acetoacetic acid about 30%), β-hydroxybutyric acid (β? Hydroxybutyric acid about 70%) and a small amount of acetone (acetone) (formula see below). Mortal blood ketone levels are very small, which is the body to use fat oxidation for the abnormal situation can be. However, in certain physiological conditions (starvation, fasting) or pathological conditions (such as diabetes), a source of sugar or oxidation can hinder, launched to enhance fat, fatty acids become the main energy supply of human material. If the liver synthesis of ketone bodies in the extrahepatic tissues to use more than the ability of ketone bodies, loss of balance between the two, mbt official website, the blood concentration will be too high, resulting in ketonemia (acetonemia) and ketone urine disease (acetonuria .) Acetoacetate and β-hydroxybutyrate are acidic, so ketones accumulate in the body can also cause acidosis. The generation of ketone ketone bodies are generated in the mitochondria of liver cells, which produce raw materials are fatty acid β-oxidation of acetyl CoA. First, two molecules acetyl-CoA under the action of the thiolase off part of coenzyme A, acetyl acetyl CoA. In the 3 – hydroxy – 3 – methyl glutaryl CoA (hydroxy methyl glutaryl? CoA, HMG-CoA) synthase catalyzed acetyl part of acetyl-CoA and acetyl-CoA and then the reaction of HMG-CoA, and part of released coenzyme. This one-step reaction is the rate-limiting step to generate ketone bodies. HMG-CoA lyase catalyzed HMG-CoA to generate acetyl-acetic acid and acetyl-CoA, which can be used for the synthesis of ketone bodies. Mitochondrial β-hydroxybutyric acid dehydrogenase-catalyzed acetoacetate hydrogenation (NADH H for hydrogen as a body), to generate β-hydroxybutyric acid, the reduction rate of resolution in the mitochondria [NADH H] / [NAD] ratio , a small amount of B stack acid decarboxylation to generate self-acetone. The ketone body generation process is actually a cycle, also known as Lei Ning cycle (lynen cycle), two molecules acetyl-CoA generated by this cycle part of acetoacetate. After the quick through the liver to generate ketone bodies mitochondrial membrane and cell membrane into the blood, transported to extrahepatic tissues used. The use of ketone bodies during skeletal muscle, heart and kidney in sulfur-transfer enzyme succinyl-CoA (succinyl? CoA thiophorase), in the presence of succinyl-CoA, the enzyme-catalyzed activation of acetoacetate to generate acetyl CoA. Heart, kidney and brain have sulfur kinase in T with the presence of ATP and coenzyme, the enzyme-catalyzed acetylation of acid activation into acetyl CoA. Generated by these two enzyme-catalyzed acetylation of acetyl-CoA under the action of the thiolase, broken down into two molecules of acetyl-CoA, acetyl-CoA into the citric acid cycle oxidation and decomposition of the main. Acetone in addition to the urine, but there is a department directly exhaled from the lungs, metabolism, does not occupy a prominent position, extrahepatic tissues using acetoacetate and β-hydroxybutyric acid in the process available under the chart performance. Liver cells do not turn sulfur enzyme succinyl-CoA and acetoacetate sulfur kinase, so the liver cells can not use ketone bodies. Extrahepatic tissues to use ketone bodies in the quantity and arterial blood ketone body concentration is proportional to the concentration of 70mg/dl from ketone bodies, the ability to use extrahepatic tissues to reach saturation. Kidney-one threshold also 70mg/dl, blood ketone body concentrations exceeding this value, the amount of ketone bodies than by glomerular filtration to renal tubular reabsorption, showing ketone urine disease. The ability to use ketone bodies in brain tissue with blood glucose is related to lower blood sugar levels only when the use of ketone bodies. Significance of ketone bodies generated 1) easy to transport ketone bodies: a long-chain fatty acids across the mitochondrial carnitine carrier transport needs, fatty acid transport in the blood need to generate a fatty acid combined with albumin albumin, and ketone bodies by the mitochondrial and transport in the blood does not require the carrier. 2) Easy to use: activation of fatty acids into the β-oxidation, 4-step reaction by the ability of each member to generate acetyl-CoA, and acetoacetate activation step response can be generated as long as two molecules of acetyl-CoA, β-hydroxybutyric acid than the use of only multi-step oxidation of acetoacetate. Therefore, ketone bodies can be seen as a fatty acid in the liver of semi-processed produce. 3) frugal use of glucose for the brain and red blood cells: the use of ketone understand extrahepatic tissues to generate a large number of acetyl CoA, a large number of acetyl-CoA inhibition of pyruvate dehydrogenase activity, limits the use of sugar. While acetyl-CoA carboxylase can activate and enhance gluconeogenesis. Extrahepatic tissues can use ketone bodies for oxidation, reduction of glucose on the need to protect the brain, red blood cells have glucose. Brain tissue can not use long-chain fatty acids, but hunger can use ketone bodies for energy, hunger 5 weeks ketone bodies for energy can be up to 70%. 4) muscle tissue to use ketone bodies, can inhibit muscle protein breakdown, avoid excessive consumption of protein, its mechanism is not yet understood. ? 5) generated an increase in ketone bodies is common in hunger, gestosis, diabetes and other conditions. Low-sugar high-fat diet can also generate an increase in ketone bodies. Foreword body fatty acid synthesis of fatty acids derived from the great local food, exogenous fatty acids in the body can be used by the body through the transformation process. Body with the opportunity to use sugar and protein can also be transformed into fatty acids as endogenous fatty acids for triglyceride formation and storage of energy. Synthesis of fatty acids is the main organ is the liver and lactating mammary gland, in addition to adipose tissue, kidney, small intestine can be synthesized fatty acids, fatty acid synthesis is acetyl raw materials directly CoA, consuming ATP and NADPH, generated first sixteen carbon palmitic acid, processed generate the body of fatty acids for synthesis in the cytoplasm. Palmitic acid generation 1 transfer of acetyl-CoA by acetyl-CoA oxidation and decomposition of sugar or fat? Curtain ⑼ Qian steamed stolen saddle chasing paper mulberry shade oA tip reaction occurred in the mitochondria, and fatty acid synthesis part of it is cytoplasmic, the mitochondrial acetyl-CoA must be transported to the cytoplasm. But not free to acetyl-CoA through the mitochondrial membrane, through a known citric acid – pyruvic acid cycle (citrate pyruvate cycle) to achieve the acetyl-CoA from the mitochondria to the cytoplasm of the transfer. First, in the mitochondria, acetyl CoA and oxaloacetate by citrate synthase catalyzed condensation of citric acid, then the corresponding mitochondrial carrier to help enter the cytosol, in the cytosol of citrate lyase in memory (citrate lyase) pyrolysis can produce acetyl-CoA and citrate oxaloacetate. The former can be used to generate fatty acids, which can be added to return the mitochondrial citric acid consumption during synthesis. However, oxaloacetate mitochondrial membrane permeability can not be free, they must be catalyzed by malate dehydrogenase, malic acid and then reduced by the carrier on the mitochondrial transport into the mitochondria, the oxidation compensate oxaloacetate. Also under the action of the malic enzyme, pyruvate oxidative decarboxylation, accompanied by the generation of NADPH. Via pyruvate is transported into the mitochondrial membrane carrier, the time can be further carboxylation of pyruvate into oxaloacetate. Pyruvate by the citric acid cycle each time, make a part of acetic acid CoA from mitochondria into the cytosol, while consumption of two molecules of ATP, the body also provides NADPH for the synthesis of the need to supplement. (2) the formation of malonyl-CoA acetyl-CoA by the acetyl-CoA carboxylase (acetyl CoA carboxylase) catalyst into malonyl CoA (also known as malonyl CoA), acetyl-CoA carboxylase present in the cytosol, The prosthetic group of biotin in the reaction process to carry and play the role of carboxyl transfer. The reaction mechanism is similar to other biotin-dependent carboxylation reactions, such as pyruvate carboxylase into oxaloacetate of the reaction. Reaction is as follows: acetyl-CoA carboxylase by the catalytic reaction of fatty acid synthesis rate-limiting step in the process. This enzyme is an allosteric enzyme, the allosteric effect of the role of agents, its non-active monomer with the active polymer (from 100 monomer was linear array) that can each change. Citric acid and citric acid can promote different monomers into a polymer to enhance the activity, and long-chain fatty acids can accelerate depolymerization, thereby inhibiting enzyme activity. Can also be acetyl-CoA carboxylase by cAMP-dependent phosphorylation and dephosphorylation to regulate the activity of polish. This enzyme activity by phosphorylation losses, such as glucagon and adrenaline can promote this phosphorylation, thus inhibiting fatty acid synthesis; and insulin can promote enzyme dephosphorylation, it can enhance acetyl-CoA carboxylase activity, accelerated fatty acid synthesis. While acetyl-CoA carboxylase is inducible enzyme, long-term high-sugar low-fat diet can induce this enzyme to generate and promote fatty acid synthesis; the other hand, high-fat low-sugar diet can inhibit this enzyme synthesis, decreased fatty acid generation. 3 palmitic acid formation in prokaryotes (eg E. coli) enzyme-catalyzed fatty acid is a function of seven different enzyme with a acyl carrier protein (acyl carrier protein, ACP) aggregate into the complex. In eukaryotes, this reaction is a catalytic subunit of the enzyme containing the double, each subunit has seven different catalytic structures in the ACP region and the structure of a commensurate area, so this is a function of the enzyme there are multiple . Different biological difference between the structure of this enzyme. Palmitic acid synthesis is actually a repeated cycle process, from a molecule acetyl-CoA and malonyl-CoA molecules by 7 transfer, condensation, hydrogenation, dehydration, and then repeat the process of hydrogenation, and each time the two carbon chain extension carbon, a total of seven times repeated, the most Bisheng Cheng containing sixteen carbon palmitic acid. Consumption of fatty acid synthesis required ATP and NADPH H, NADPH mainly from glucose decomposition of pentose phosphate path. In addition, the oxidative decarboxylation of malic acid may also occur in a small amount of NADPH. Fatty acid β-oxidation process is not the reverse process, the organization of their response, cellular localization, transfer vector, acyl carrier, rate-limiting enzyme, activator, inhibitor, for the hydrogen donor and by the hydrogen donor and the reaction substrate and product are not identical. Other fatty acids generated in the body not only palmitic acid, as well as carbon chain length ranging from other fatty acids, there are a variety of unsaturated fatty acids, in addition to nutrition, essential fatty acids attached to the food supply, other fatty acids may be represented by palmitic acid in the cell processing adapted from. 1 extension and shortening the carbon chain fatty acid carbon chain shortened by the mitochondrial β-oxidation in the completion, after a β-oxidation cycle can be reduced by two carbon atoms. ? Fatty acid carbon chain extension in the smooth endoplasmic reticulum and mitochondria catalyzed by the enzyme fatty acid extension to complete. Endoplasmic reticulum, palmitic acid extension is malonyl-CoA units for the two-carbon donor, the NADPH H for hydrogen, but also by condensation decarboxylation, reduction process to extend the carbon chain, and the synthesis of fatty acids in cytosol-based prototype the same. However, the enzyme catalytic reaction systems, the fatty acyl-ACP as the carrier not to, but connected with coenzyme A to participate in reactions. In addition to normal brain tissue to synthesize stearic acid (18C) mainly due to brain tissue with other enzymes, it may be extended to 24 carbon fatty acids for brain lipid metabolism needs. ? In the mitochondria, mitochondrial fatty acid palmitic acid by the enzyme system to extend the role of acetyl-CoA condensation with the gradual extension of the carbon chain, the process is reversed with the fatty acid β-oxidation reaction is similar to enoyl-CoA reductase only the coenzyme is NADPH H and β-oxidation process are different. By this method the general fatty acid carbon chain may be extended to 24 or 26 carbon, but stearic acid up. (2) fatty acid desaturation and animal tissues contain mainly unsaturated fatty acids oleic acid soft (16:1 △ 9), oleic acid (18:1 △ 9), linoleic acid (18:2 △ 9,12), linolenic acid (18:3 △ 9, mbt discontinued styles, 12,15), arachidonic acid (20:4 △ 5,8,11,14) and so on. One of the most common monounsaturated fatty acid oleic acid and oleic acid by a corresponding soft-fatty acids activated by the desaturase (acylCoAdesaturase) catalytic dehydrogenation. Type of enzyme present in the smooth endoplasmic reticulum, is a mixed function oxidase; for enzyme catalysis only result in △ 9 double bond, but not in C10 and double bond between the methyl end, it is linoleic acid (linoleate) , linolenic acid (linolenate) and arachidonic acid (arachidonate) synthesis in the body can not synthesize or less. But they are also not lacking in the body, so must the food supply, mbt wanda chocolate Second Temple, therefore, called essential fatty acids (essential fatty acid). Plant tissue with that end in C-10 methyl and double bond between the composition (ie ω3 and ω6) of the desaturase, can synthesize these three polyunsaturated fatty acids. When, after ingestion of linoleic acid, in animals and by extension to the saturated carbon chain, may produce arachidonic acid. Fatty acid biosynthesis acetyl-CoA carboxylase-catalyzed reaction is rate-limiting steps in fatty acid synthesis, lot of factors can influence this activity, so that changes in fatty acid synthesis rate. Fatty acid synthesis in other enzymes, such as fatty acid synthase, citrate cleavage enzyme can be adjusted. 1 metabolites in the regulation of high-fat diet, the result of fat mobilization or enhanced because of hunger, the cells increase in soft acyl CoA can inhibit the acetyl-CoA carboxylase feedback, thereby inhibiting fatty acid synthesis in vivo. The consumption of sugar, glucose metabolism is increased, the glucose oxidation and pentose phosphate cycle provides an increase in acetyl-CoA and NADPH, the increase in raw material fatty acids beneficial fatty acid synthesis. In addition, enhanced glucose oxidation results, the increase in intracellular ATP and inhibit isocitrate dehydrogenase, citric acid and citric acid deposition caused by differences in the corresponding mitochondrial carrier assistance from the mitochondria into the cytosol, can be allosteric activation of acetyl-CoA carboxylase. At the same time their release can also be acetyl cleavage CoA, increased fatty acid synthesis of raw materials, so that fatty acid synthesis. (2) hormonal regulation of insulin, glucagon, epinephrine and growth hormone etc involved in the regulation of fatty acid synthesis. Insulin-induced acetyl-CoA carboxylase, fatty acid synthase citrate lyase synthesis, thereby contributing to fatty acid synthesis. There is also the acetyl-CoA carboxylase by promoting dephosphorylation of leaving the activity increased, but also fatty acid synthesis to accelerate. Glucagon, etc. can increase cAMP, resulting in phosphorylation of acetyl-CoA carboxylase activity decreases, so the inhibition of fatty acid synthesis. In addition, glucagon also inhibits triglyceride synthesis, thereby increasing the long-chain acyl-CoA acetyl-CoA carboxylase of feedback inhibition, but also the fatty acid synthesis was inhibited. Maintenance of health-related information about fat, whether vegetable or animal fats have 9 per gram calories. However, decomposition of vegetable oils contain fatty substances, moderate intake is beneficial, but it does not mean that the heat low. Most people think that vegetable oil is insurance, you can eat, this is the fault of the point of view, people need to lose weight limits Qidan feeding vegetable oil, so adverse to lose weight, be healthy long-lived people should predicament. There are three types of fatty acids people need: polyunsaturated fatty acids, monounsaturated fatty acids and saturated fatty acids. We used cooking oil usually contain three fatty acids the body needs. Per person per day total daily fat intake only 20% of total food calories, (dominated by the daily fuel consumption of 15 to 30 ml) each of the three fatty acids every day, eat together, can not prefer any oil, fat intake or imbalance, the formation of disease. Monounsaturated fatty acids daily food intake to account for 10% polyunsaturated fatty acids to account for 10%, while the saturated fatty acids to less than 10. Animal oil, coconut oil and palm oil is the main component of saturated fatty acids, and polyunsaturated fatty acids is very low. Heart disease give up saturated animal oil, vegetable oil intake from saturated vegetable oil. Olive oil, nut oil (A glycerol), rapeseed oil, corn oil, peanut oil high content of monounsaturated fatty acids, three fatty acids the body needs in order to monounsaturated fatty acid requirements for maximum corn oil, olive Oil can be used as an important source of this fatty acid. Sunflower oil, corn oil, soybean oil and animal fat with continental fish are mostly polyunsaturated fatty acids.
