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What Converts Amino Acids To Glucose?

Gluconeogenesis - An Overview | Sciencedirect Topics

Gluconeogenesis - An Overview | Sciencedirect Topics

Gluconeogenesis is the process that leads to the generation of glucose from a variety of sources such as pyruvate, lactate, glycerol, and certain amino acids. Larry R. Engelking, in Textbook of Veterinary Physiological Chemistry (Third Edition) , 2015 Gluconeogenesis occurs in the liver and kidneys. Gluconeogenesis supplies the needs for plasma glucose between meals. Gluconeogenesis is stimulated by the diabetogenic hormones (glucagon, growth hormone, epinephrine, and cortisol). Gluconeogenic substrates include glycerol, lactate, propionate, and certain amino acids. PEP carboxykinase catalyzes the rate-limiting reaction in gluconeogenesis. The dicarboxylic acid shuttle moves hydrocarbons from pyruvate to PEP in gluconeogenesis. Gluconeogenesis is a continual process in carnivores and ruminant animals, therefore they have little need to store glycogen in their liver cells. Of the amino acids transported to liver from muscle during exercise and starvation, Ala predominates. b-Aminoisobutyrate, generated from pyrimidine degradation, is a (minor) gluconeogenic substrate. N.V. Bhagavan, Chung-Eun Ha, in Essentials of Medical Biochemistry , 2011 Gluconeogenesis refers to synthesis of new glucose from noncarbohydrate precursors, provides glucose when dietary intake is insufficient or absent. It also is essential in the regulation of acid-base balance, amino acid metabolism, and synthesis of carbohydrate derived structural components. Gluconeogenesis occurs in liver and kidneys. The precursors of gluconeogenesis are lactate, glycerol, amino acids, and with propionate making a minor contribution. The gluconeogenesis pathway consumes ATP, which is derived primarily from the oxidation of fatty acids. The pathway uses several enzymes of the glycolysis with the exception of enzymes Continue reading >>

Can Sugars Be Produced From Fatty Acids? A Test Case For Pathway Analysis Tools

Can Sugars Be Produced From Fatty Acids? A Test Case For Pathway Analysis Tools

Can sugars be produced from fatty acids? A test case for pathway analysis tools Department of Bioinformatics, 2Bio Systems Analysis Group, Friedrich-Schiller-Universitt Jena, Ernst-Abbe-Platz 2, 07743 Jena, Germany and 3School of Life Sciences, Oxford Brookes University, Headington, Oxford, OX3 0BP, UK *To whom correspondence should be addressed. Search for other works by this author on: Department of Bioinformatics, 2Bio Systems Analysis Group, Friedrich-Schiller-Universitt Jena, Ernst-Abbe-Platz 2, 07743 Jena, Germany and 3School of Life Sciences, Oxford Brookes University, Headington, Oxford, OX3 0BP, UK *To whom correspondence should be addressed. Search for other works by this author on: Department of Bioinformatics, 2Bio Systems Analysis Group, Friedrich-Schiller-Universitt Jena, Ernst-Abbe-Platz 2, 07743 Jena, Germany and 3School of Life Sciences, Oxford Brookes University, Headington, Oxford, OX3 0BP, UK Search for other works by this author on: Department of Bioinformatics, 2Bio Systems Analysis Group, Friedrich-Schiller-Universitt Jena, Ernst-Abbe-Platz 2, 07743 Jena, Germany and 3School of Life Sciences, Oxford Brookes University, Headington, Oxford, OX3 0BP, UK Search for other works by this author on: Bioinformatics, Volume 25, Issue 1, 1 January 2009, Pages 152158, Luis F. de Figueiredo, Stefan Schuster, Christoph Kaleta, David A. Fell; Can sugars be produced from fatty acids? A test case for pathway analysis tools, Bioinformatics, Volume 25, Issue 1, 1 January 2009, Pages 152158, Motivation: In recent years, several methods have been proposed for determining metabolic pathways in an automated way based on network topology. The aim of this work is to analyse these methods by tackling a concrete example relevant in biochemistry. It concerns the question wh Continue reading >>

Glucose Can Be Synthesized From Noncarbohydrate Precursors - Biochemistry - Ncbi Bookshelf

Glucose Can Be Synthesized From Noncarbohydrate Precursors - Biochemistry - Ncbi Bookshelf

Glucose is formed by hydrolysis of glucose 6-phosphate in a reaction catalyzed by glucose 6-phosphatase. We will examine each of these steps in turn. 16.3.2. The Conversion of Pyruvate into Phosphoenolpyruvate Begins with the Formation of Oxaloacetate The first step in gluconeogenesis is the carboxylation of pyruvate to form oxaloacetate at the expense of a molecule of ATP . Then, oxaloacetate is decarboxylated and phosphorylated to yield phosphoenolpyruvate, at the expense of the high phosphoryl-transfer potential of GTP . Both of these reactions take place inside the mitochondria. The first reaction is catalyzed by pyruvate carboxylase and the second by phosphoenolpyruvate carboxykinase. The sum of these reactions is: Pyruvate carboxylase is of special interest because of its structural, catalytic, and allosteric properties. The N-terminal 300 to 350 amino acids form an ATP -grasp domain ( Figure 16.25 ), which is a widely used ATP-activating domain to be discussed in more detail when we investigate nucleotide biosynthesis ( Section 25.1.1 ). The C -terminal 80 amino acids constitute a biotin-binding domain ( Figure 16.26 ) that we will see again in fatty acid synthesis ( Section 22.4.1 ). Biotin is a covalently attached prosthetic group, which serves as a carrier of activated CO2. The carboxylate group of biotin is linked to the -amino group of a specific lysine residue by an amide bond ( Figure 16.27 ). Note that biotin is attached to pyruvate carboxylase by a long, flexible chain. The carboxylation of pyruvate takes place in three stages: Recall that, in aqueous solutions, CO2 exists as HCO3- with the aid of carbonic anhydrase (Section 9.2). The HCO3- is activated to carboxyphosphate. This activated CO2 is subsequently bonded to the N-1 atom of the biotin ring to Continue reading >>

Introduction To The Degradation And The Synthesis Of Glucose

Introduction To The Degradation And The Synthesis Of Glucose

Content: 1. Introduction to the degradation and the synthesis of glucose 2. Glycolysis 3. Gluconeogenesis _ Saccharides are one of the main nutrients for heterotrophic organisms. Saccharides can be found in each cell of the human body. Saccharides have many different functions: (1) source of energy, (2) source of carbon atoms for syntheses, (3) reserves of energy (glycogen), (4) structural function (proteoglycans). Glucose (Glc) is universal energetic substrate. One gram of glucose when oxidized provides 17 kJ (= 4 kcal). Of great importance is fact that our cells are capable of draining energy from glucose even in anaerobic conditions – this is not true for any other nutrient we use. There are some populations of cells that are strictly dependent on glucose – i.e. erythrocytes, cells of central nervous system, etc…. We would like to emphasize that pyruvate dehydrogenase reaction (PDH) is irreversible therefore it is not possible to synthesise glucose from fatty acids. Au contraire our cells are capable of converting excessive glucose into fatty acids and then into TAG. Glucose blood concentration is called glycemia. Glycemia is normally 3,3 – 5,6 mmol/l, glycemia can after a meal increase to 7,0 mmol/l. In physiological conditions glucose is not present in the urine. In case that glycemia is higher than 10,0 mmol/l the renal threshold is exceeded and glucose gets into the urine. This condition is called glycosuria. Thus when glycemia is higher than renal threshold (value of threshold is 10,0 mmol/l) glucose can be found in the urine. In the food is glucose in several forms: (1) free glucose, (2) part of oligosaccharides (predominantly disaccharides), and (3) part of polysaccharides. To the blood is from intestine released only free glucose. Sources of blood glu Continue reading >>

Principles Of Biochemistry/gluconeogenesis And Glycogenesis

Principles Of Biochemistry/gluconeogenesis And Glycogenesis

Gluconeogenesis (abbreviated GNG) is a metabolic pathway that results in the generation of glucose from non-carbohydrate carbon substrates such as lactate, glycerol, and glucogenic amino acids. It is one of the two main mechanisms humans and many other animals use to keep blood glucose levels from dropping too low (hypoglycemia). The other means of maintaining blood glucose levels is through the degradation of glycogen (glycogenolysis). Gluconeogenesis is a ubiquitous process, present in plants, animals, fungi, bacteria, and other microorganisms. In animals, gluconeogenesis takes place mainly in the liver and, to a lesser extent, in the cortex of kidneys. This process occurs during periods of fasting, starvation, low-carbohydrate diets, or intense exercise and is highly endergonic. For example, the pathway leading from phosphoenolpyruvate to glucose-6-phosphate requires 6 molecules of ATP. Gluconeogenesis is often associated with ketosis. Gluconeogenesis is also a target of therapy for type II diabetes, such as metformin, which inhibits glucose formation and stimulates glucose uptake by cells. Lactate is transported back to the liver where it is converted into pyruvate by the Cori cycle using the enzyme lactate dehydrogenase. Pyruvate, the first designated substrate of the gluconeogenic pathway, can then be used to generate glucose. All citric acid cycle intermediates, through conversion to oxaloacetate, amino acids other than lysine or leucine, and glycerol can also function as substrates for gluconeogenesis.Transamination or deamination of amino acids facilitates entering of their carbon skeleton into the cycle directly (as pyruvate or oxaloacetate), or indirectly via the citric acid cycle. Whether fatty acids can be converted into glucose in animals has been a longst Continue reading >>

In Silico Evidence For Gluconeogenesis From Fatty Acids In Humans

In Silico Evidence For Gluconeogenesis From Fatty Acids In Humans

Abstract The question whether fatty acids can be converted into glucose in humans has a long standing tradition in biochemistry, and the expected answer is “No”. Using recent advances in Systems Biology in the form of large-scale metabolic reconstructions, we reassessed this question by performing a global investigation of a genome-scale human metabolic network, which had been reconstructed on the basis of experimental results. By elementary flux pattern analysis, we found numerous pathways on which gluconeogenesis from fatty acids is feasible in humans. On these pathways, four moles of acetyl-CoA are converted into one mole of glucose and two moles of CO2. Analyzing the detected pathways in detail we found that their energetic requirements potentially limit their capacity. This study has many other biochemical implications: effect of starvation, sports physiology, practically carbohydrate-free diets of inuit, as well as survival of hibernating animals and embryos of egg-laying animals. Moreover, the energetic loss associated to the usage of gluconeogenesis from fatty acids can help explain the efficiency of carbohydrate reduced and ketogenic diets such as the Atkins diet. Author Summary That sugar can be converted into fatty acids in humans is a well-known fact. The question whether the reverse direction, i.e., gluconeogenesis from fatty acids, is also feasible has been a topic of intense debate since the end of the 19th century. With the discovery of the glyoxylate shunt that allows this conversion in some bacteria, plants, fungi and nematodes it has been considered infeasible in humans since the corresponding enzymes could not be detected. However, by this finding only a single route for gluconeogenesis from fatty acids has been ruled out. To address the question Continue reading >>

Gluconeogenesis

Gluconeogenesis

Glucose is a key metabolite in human metabolism, but it is not always available at sufficient levels in the diet. Therefore, a pathway exists that converts other foodstuffs into glucose. This pathway is called gluconeogenesis. 7.1.1 Glucose is an indispensable metabolite The brain requires at least ~50% of its calories in the form of glucose Red blood cells exclusively subsist on glucose Glucose is a precursor of other sugars needed in the biosynthesis of nucleotides, glycoproteins, and glycolipids Glucose is needed to replenish NADPH, which supplies reducing power for biosynthesis and detoxification These considerations make the need for gluconeogenesis quite clear—we can’t just leave the blood glucose level up to the vagaries of dietary supply. Gluconeogenesis is the reversal of glycolysis, with several workarounds for the irreversible reactions in that pathway. In this scheme, the reactions that are shared between glycolysis and gluconeogenesis are shown in blue, whereas reactions that are specific for gluconeogenesis are shown in red. As you can see, both pyruvate and oxaloacetate are starting points for red arrows; therefore, any pathway that yields either of these, or indeed any other intermediate of glycolysis, can supply substrate carbon for gluconeogenesis. These pathways are indicated here by green arrows. The major substrate supply for gluconeogenesis is protein, both dietary and endogenous. Protein is first broken down into its constituent amino acids. Those amino acids that can be converted to pyruvate or any of the TCA cycle intermediates can serve as substrates for gluconeogenesis, and are therefore called glucogenic. Leucine, lysine and the aromatic amino acids are degraded to acetyl-CoA or acetoacetate. Since acetoacetate is a ketone body, and acety Continue reading >>

Glucogenic Amino Acids

Glucogenic Amino Acids

DOUGLAS C. HEIMBURGER MD, in Handbook of Clinical Nutrition (Fourth Edition) , 2006 The major aim of protein catabolism during a state of starvation is to provide the glucogenic amino acids (especially alanine and glutamine) that serve as substrates for endogenous glucose production (gluconeogenesis) in the liver. In the hypometabolic/starved state, protein breakdown for gluconeogenesis is minimized, especially as ketones become the substrate preferred by certain tissues. In the hypermetabolic/stress state, gluconeogenesis increases dramatically and in proportion to the degree of the insult to increase the supply of glucose (the major fuel of reparation). Glucose is the only fuel that can be utilized by hypoxic tissues (anaerobic glycolysis), by phagocytosing (bacteria-killing) white cells, and by young fibroblasts. Infusions of glucose partially offset a negative energy balance but do not significantly suppress the high rates of gluconeogenesis in the catabolic patient. Hence, adequate supplies of protein are needed to replace the amino acids utilized for this metabolic response. In summary, the two physiologic states represent different responses to starvation. The hypometabolic patient, who conserves body mass by reducing the metabolic rate and using fat as the primary fuel (rather than glucose and its precursor amino acids), is adapted to starvation. The hypermetabolic patient also uses fat as a fuel but rapidly breaks down body protein to produce glucose, the fuel of reparation, thereby causing loss of muscle and organ tissue and endangering vital body functions. Joerg Klepper*, in Handbook of Clinical Neurology , 2013 Gluconeogenesis, predominantly in the liver, generates glucose from noncarbohydrate substrates such as lactate, glycerol, and glucogenic amino acid Continue reading >>

Free Biochemistry Flashcards About Exam 4 Biochemistry

Free Biochemistry Flashcards About Exam 4 Biochemistry

Where does the energy needed for gluconeogenesis come from? The liver uses fatty acids in the fasting state to form ketone bodies. Burning fatty acids produces lots of ATP and it also produces lots of acetyl-CoA to make sure that the lactate and alanine that the liver is taking up get converted to glucose. What are the two major amino acids in our blood and what are they used for? Glutamine is the number 1 amino acid in our blood and alanine is number 2 (in terms of concentration). (alanine forms pyruvate and glutamine forms alpha-ketogluterate). How are amino acids used to synthesize glucose and which two amino acids cant be used to synthesize glucose? Synthesize through gluconeogenisis and Leucine and Lysine. Discuss the general process used for gluconeogenesis? (What are we reversing and where are we doing it?) A sort of reversal of glycolysis, from pyruvate back to glucose in just the mitochondria and cytoplasm of cells in the liver and kidney. Most steps are reversible but some you have to use completely different enzymes. List the 3 steps (enzymes) in glycolysis that are not reversible. PEP -> pyruvateGlucose-6-PO4 -> GlucoseF-1,6 BP -> F-6-PO4Overall message, gluconeogenesis features enzymes that bypass irreversible KINASE steps How is glucose released from the liver during gluconeogenesis? (enzyme used and the process used for the release of glucose). Glucose-6-Phosphatase; Remember that the liver is using Glucokinase (hexokinase IV).So this acts as the reversal of hexokinase and takes phosphate of G6P. How is glucose transported to the membrane, does it need glut 2? Presence of G-6-phosphatase in ER of the liver and kidney cells makes gluconeogenesis possible. Muscle and brain DO NOT do gluconeogenesis. G-6-P is hydrolyzed as it passes into the ER. ER vesicles Continue reading >>

Gluconeogenesis

Gluconeogenesis

Not to be confused with Glycogenesis or Glyceroneogenesis. Simplified Gluconeogenesis Pathway Gluconeogenesis (GNG) is a metabolic pathway that results in the generation of glucose from certain non-carbohydrate carbon substrates. From breakdown of proteins, these substrates include glucogenic amino acids (although not ketogenic amino acids); from breakdown of lipids (such as triglycerides), they include glycerol (although not fatty acids); and from other steps in metabolism they include pyruvate and lactate. Gluconeogenesis is one of several main mechanisms used by humans and many other animals to maintain blood glucose levels, avoiding low levels (hypoglycemia). Other means include the degradation of glycogen (glycogenolysis)[1] and fatty acid catabolism. Gluconeogenesis is a ubiquitous process, present in plants, animals, fungi, bacteria, and other microorganisms.[2] In vertebrates, gluconeogenesis takes place mainly in the liver and, to a lesser extent, in the cortex of the kidneys. In ruminants, this tends to be a continuous process.[3] In many other animals, the process occurs during periods of fasting, starvation, low-carbohydrate diets, or intense exercise. The process is highly endergonic until it is coupled to the hydrolysis of ATP or GTP, effectively making the process exergonic. For example, the pathway leading from pyruvate to glucose-6-phosphate requires 4 molecules of ATP and 2 molecules of GTP to proceed spontaneously. Gluconeogenesis is often associated with ketosis. Gluconeogenesis is also a target of therapy for type 2 diabetes, such as the antidiabetic drug, metformin, which inhibits glucose formation and stimulates glucose uptake by cells.[4] In ruminants, because dietary carbohydrates tend to be metabolized by rumen organisms, gluconeogenesis occurs Continue reading >>

Can Amino Acids Be Used By The Body To Make Glucose & Fatty Acids?

Can Amino Acids Be Used By The Body To Make Glucose & Fatty Acids?

Amino acids are nitrogen-containing molecules that are the building blocks of all proteins in food and in the body. They can be used as energy, yielding about 4 calories per gram, but their primary purpose is the synthesis and maintenance of body proteins including, but not limited to, muscle mass. Video of the Day During normal protein metabolism, a certain number of amino acids are pushed aside each day. When these amino acids are disproportionate to other amino acids for the synthesis of new protein, your liver and kidneys dispose of the nitrogen as urea, and the rest of the molecule is used as energy in a variety of ways. Then certain amino acids -- minus their nitrogen -- can enter the citric acid cycle -- the biochemical pathway that converts food into energy. Others can be converted to glucose or fat. This process may be enhanced when you take in more protein than you need. Your body relies on a continuous supply of glucose and fatty acids for energy for physical activity and cellular needs during rest. When you exercise, your body relies still more on glucose because fat is slower to metabolize. The higher your exercise intensity is, the more your body requires quicker-burning glucose. Some glucose is stored as glycogen in the liver and muscles and can be recruited when blood glucose is used up. When glycogen becomes depleted, the process of gluconeogenesis can take over -- the creation of new glucose from another source. The usual source for gluconeogenesis is amino acids. Healthy people store adequate body fat to cover their energy needs. Although certain amino acids can be converted to fatty acids, there should be no need for this to occur in order to supply energy. But if a very high protein intake adds substantially more calories, theoretically those extra Continue reading >>

Gluconeogenesis: Endogenous Glucose Synthesis

Gluconeogenesis: Endogenous Glucose Synthesis

Reactions of Gluconeogenesis: Gluconeogenesis from two moles of pyruvate to two moles of 1,3-bisphosphoglycerate consumes six moles of ATP. This makes the process of gluconeogenesis very costly from an energy standpoint considering that glucose oxidation to two moles of pyruvate yields two moles of ATP. The major hepatic substrates for gluconeogenesis (glycerol, lactate, alanine, and pyruvate) are enclosed in red boxes for highlighting. The reactions that take place in the mitochondria are pyruvate to OAA and OAA to malate. Pyruvate from the cytosol is transported across the inner mitochondrial membrane by the pyruvate transporter. Transport of pyruvate across the plasma membrane is catalyzed by the SLC16A1 protein (also called the monocarboxylic acid transporter 1, MCT1) and transport across the outer mitochondrial membrane involves a voltage-dependent porin transporter. Transport across the inner mitochondrial membrane requires a heterotetrameric transport complex (mitochondrial pyruvate carrier) consisting of the MPC1 gene and MPC2 gene encoded proteins. Following reduction of OAA to malate the malate is transported to the cytosol by the malate transporter (SLC25A11). In the cytosol the malate is oxidized to OAA and the OOA then feeds into the gluconeogenic pathway via conversion to PEP via PEPCK. The PEPCK reaction is another site for consumption of an ATP equivalent (GTP is utilized in the PEPCK reaction). The reversal of the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) reaction requires a supply of NADH. When lactate is the gluconeogenic substrate the NADH is supplied by the lactate dehydrogenase (LDH) reaction (indicated by the dashes lines), and it is supplied by the malate dehydrogenase reaction when pyruvate and alanine are the substrates. Secondly, one mo Continue reading >>

Gluconeogenesis Definition

Gluconeogenesis Definition

The literal meaning of Gluconeogenesis is GLUCO – glucose; NEO – new; GENESIS – creation. Thus Gluconeogenesis is a biochemical term that describes the synthesis of glucose or glycogen from substances which are not carbohydrates. Gluconeogenesis is the procedure that generates the energy giving fuel ’ glucose’ from substances other than carbohydrates, which are stored in the body , when the carbohydrate substrates are not sufficiently available as in starvation or when they are of great demand as in intense physical exertion. [1,2,3,4] Gluconeogenesis Pathway Basically Gluconeogenesis is the reversal of Glycolysis which is the process of breaking down of glucose to produce energy. [1]Glycolysis proceeds to another energy cycle called Citric acid cycle by forming a substance called pyruvate. So, Gluconeogenesis is just the reversal of Glycolysis – starting with pyruvate. The substrates get converted to pyruvate or other intermediates of the Citric acid cycle by various chemical reactions from which Gluconeogenesis begins. Which way does the process go if all the set of enzymes are same for both glucose synthesis and breakdown? This conflict is overcome by the 3 key steps in Gluconeogenesis which cannot occur with enzymes of Glycolysis. So these 3 steps are circumvented by another set of enzymes to form glucose at the end. Substrates of Gluconeogenesis Glucogenic amino acids like alanine and glutamine Lactate which is produced as a byproduct of glycolysis in muscles, red blood cells etc Glycerol, which is a part of triacylglecerol molecule in adipose tissue Fatty acid Citric acid cycle intermediates through oxaloacetic acid Glucogenic amino acids Glucogenic amino acid undergoes transamination which causes change in the carbon skeleton and directly gets convert Continue reading >>

We Really Can Make Glucose From Fatty Acids After All! O Textbook, How Thy Biochemistry Hast Deceived Me!

We Really Can Make Glucose From Fatty Acids After All! O Textbook, How Thy Biochemistry Hast Deceived Me!

Biochemistry textbooks generally tell us that we can’t turn fatty acids into glucose. For example, on page 634 of the 2006 and 2008 editions of Biochemistry by Berg, Tymoczko, and Stryer, we find the following: Animals Cannot Convert Fatty Acids to Glucose It is important to note that animals are unable to effect the net synthesis of glucose from fatty acids. Specficially, acetyl CoA cannot be converted into pyruvate or oxaloacetate in animals. In fact this is so important that it should be written in italics and have its own bold heading! But it’s not quite right. Making glucose from fatty acids is low-paying work. It’s not the type of alchemy that would allow us to build imperial palaces out of sugar cubes or offer hourly sweet sacrifices upon the altar of the glorious god of glucose (God forbid!). But it can be done, and it’ll help pay the bills when times are tight. All Aboard the Acetyl CoA! When we’re running primarily on fatty acids, our livers break the bulk of these fatty acids down into two-carbon units called acetate. When acetate hangs out all by its lonesome like it does in a bottle of vinegar, it’s called acetic acid and it gives vinegar its characteristic smell. Our livers aren’t bottles of vinegar, however, and they do things a bit differently. They have a little shuttle called coenzyme A, or “CoA” for short, that carries acetate wherever it needs to go. When the acetate passenger is loaded onto the CoA shuttle, we refer to the whole shebang as acetyl CoA. As acetyl CoA moves its caboose along the biochemical railway, it eventually reaches a crossroads where it has to decide whether to enter the Land of Ketogenesis or traverse the TCA cycle. The Land of Ketogenesis is a quite magical place to which we’ll return in a few moments, but n Continue reading >>

Glucogenic Amino Acid

Glucogenic Amino Acid

Paulo Ricardo Nazrio Viecili*12, ... Jonatas Z. Klafke*3, in Advances in Clinical Chemistry , 2017 TGs are lipid molecules formed by glycerol derived from carbon hydrates and/or gluconeogenic amino acids, bound to three FAs. These FAs have a similar conformation in most TG molecules: there is a saturated FA in position 1, an unsaturated FA in position 2, and a long-chain FA in position 3 (see Fig. 1) [1]. TGs are the most abundant lipids in nature, and their main characteristic is their essentially nonpolar nature, since the polar regions of their precursors (glycerol hydroxyls and carboxyls of the FAs) vanish when the ester bonds are formed. Animal fats and vegetable oils are complexes formed by TGs, the difference between them being the specific FAs that compose them. TGs in animal fats are predominantly composed of saturated FAs, lending them their solid appearance, while unsaturated FAs predominate in vegetable oils, giving them their liquid consistency. Both animal fats and vegetable oils can be digested in the organism thanks to hydrolysis by lipases [15]. TGs are synthesized through two main pathways: the glycerol phosphate pathway and the monoacylglycerol (MAG) pathway. The glycerol phosphate pathway is more common and is present in various cell types. This pathway is based on the acylation of glycerol 3-phosphate through the addition of FA groups, each of which is catalyzed by a different enzyme. In contrast, the MAG pathway predominates in the small intestine and generates TGs based on MAG derived from dietary fat. The glycerol phosphate pathway occurs as follows: first, acylation of glycerol 3-phosphate (addition of FA) occurs by the glycerol 3-phosphate acyltransferase, which is present in the endoplasmic reticulum and mitochondria, forming lysophosphatidic Continue reading >>

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