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How Is Glucose Made From Amino Acids?

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 >>

. That's The Process By Which Dna Instructions Are

. That's The Process By Which Dna Instructions Are

The Molecules of Life Proteins Proteins are the primary building materials of the body. Your hair, skin, muscles, and organs are composed mostly of proteins. Proteins are strong yet flexible, and they have a complex 3-D structure. Amino acids are the basic building blocks of proteins. Amino acids have an NH2 (amine) group on one end, a H-O-C=O (carboxyl) group on the other end, making it acidic, and an R group which extends from the central carbon atom. The chemical makeup of this R group varies from one amino acid to another and gives each amino acid its unique properties. There are 20 amino acids that are important to humans, and all proteins are made from combinations of these subunits. Chains of amino acids are called peptides. In the poly-peptide chain shown below, can you see the individual amino acids that are strung together in a repeating N-C-C pattern? Between the terminal C of one amino acid and the N of the next one, energy from ATP is used to pull the O-H from the C, and the H from the N, forming H2O and joining them in a peptide bond, lengthening the chain. When we get to the genetics section of the course, we will study protein synthesis. That's the process by which DNA instructions are transcribed into RNA, which is then translated into the amino acids that are strung together to form long poly-peptide chains. These chains are then woven together like strands in a rope or like threads in a blanket to form various proteins. When food is consumed, the proteins are broken down into their constituent amino acids and rebuilt into the proteins of the body. However, excess amino acids are not stored for future use, and the body only starts to break down its own proteins during starvation, when the ordinary sources of fuel (fats and carbohydrates) are not availa 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 >>

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 >>

How Food Works

How Food Works

You have probably heard of "carbohydrates" and "complex carbohydrates." Carbohydrates provide your body with its basic fuel. Your body thinks about carbohydrates like a car engine thinks about gasoline. The simplest carbohydrate is glucose. Glucose, also called "blood sugar" and "dextrose," flows in the bloodstream so that it is available to every cell in your body. Your cells absorb glucose and convert it into energy to drive the cell. Specifically, a set of chemical reactions on glucose creates ATP (adenosine triphosphate), and a phosphate bond in ATP powers most of the machinery in any human cell. If you drink a solution of water and glucose, the glucose passes directly from your digestive system into the bloodstream. The word "carbohydrate" comes from the fact that glucose is made up of carbon and water. The chemical formula for glucose is: You can see that glucose is made of six carbon atoms (carbo...) and the elements of six water molecules (...hydrate). Glucose is a simple sugar, meaning that to our tongues it tastes sweet. There are other simple sugars that you have probably heard of. Fructose is the main sugar in fruits. Fructose has the same chemical formula as glucose (C6H12O6), but the atoms are arranged slightly differently. The liver converts fructose to glucose. Sucrose, also known as "white sugar" or "table sugar," is made of one glucose and one fructose molecule bonded together. Lactose (the sugar found in milk) is made of one glucose and one galactose molecule bonded together. Galactose, like fructose, has the same chemical components as glucose but the atoms are arranged differently. The liver also converts galactose to glucose. Maltose, the sugar found in malt, is made from two glucose atoms bonded together. Glucose, fructose and galactose are monosa Continue reading >>

Storage And Use Of Glucose

Storage And Use Of Glucose

The glucose produced in photosynthesis may be used in various ways by plants and algae. Storage Glucose is needed by cells for respiration. However, it is not produced at night when it is too dark for photosynthesis to happen. Plants and algae store glucose as insoluble products. These include: Use Some glucose is used for respiration to release energy. Some is used to produce: Plants also need nitrates to make proteins. These are absorbed from the soil as nitrate ions. Three factors can limit the speed of photosynthesis: light intensity, carbon dioxide concentration and temperature. Without enough light, a plant cannot photosynthesise very quickly, even if there is plenty of water and carbon dioxide. Increasing the light intensity will boost the speed of photosynthesis. Sometimes photosynthesis is limited by the concentration of carbon dioxide in the air. Even if there is plenty of light, a plant cannot photosynthesise if there is insufficient carbon dioxide. If it gets too cold, the rate of photosynthesis will decrease. Plants cannot photosynthesise if it gets too hot. If you plot the rate of photosynthesis against the levels of these three limiting factors, you get graphs like the ones above. In practice, any one of these factors could limit the rate of photosynthesis. Farmers can use their knowledge of factors limiting the rate of photosynthesis to increase crop yields. This is particularly true in greenhouses, where the conditions are more easily controlled than in the open air outside: The use of artificial light allows photosynthesis to continue beyond daylight hours. Bright lights also provide a higher-than-normal light intensity. The use of artificial heating allows photosynthesis to continue at an increased rate. The use of additional carbon dioxide released i 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 >>

Metabolism Of Molecules Other Than Glucose

Metabolism Of Molecules Other Than Glucose

You have learned about the catabolism of glucose, which provides energy to living cells. But living things consume more than just glucose for food. How does a turkey sandwich, which contains various carbohydrates, lipids, and protein, provide energy to your cells? Basically, all of these molecules from food are converted into molecules that can enter the cellular respiration pathway somewhere. Some molecules enter at glycolysis, while others enter at the citric acid cycle. This means that all of the catabolic pathways for carbohydrates, proteins, and lipids eventually connect into glycolysis and the citric acid cycle pathways. Metabolic pathways should be thought of as porous—that is, substances enter from other pathways, and other substances leave for other pathways. These pathways are not closed systems. Many of the products in a particular pathway are reactants in other pathways. Carbohydrates So far, we have discussed the carbohydrate from which organisms derive the majority of their energy: glucose. Many carbohydrate molecules can be broken down into glucose or otherwise processed into glucose by the body. Glycogen, a polymer of glucose, is a short-term energy storage molecule in animals (Figure 1). When there is plenty of ATP present, the extra glucose is converted into glycogen for storage. Glycogen is made and stored in the liver and muscle. Glycogen will be taken out of storage if blood sugar levels drop. The presence of glycogen in muscle cells as a source of glucose allows ATP to be produced for a longer time during exercise. Figure 1 Glycogen is made of many molecules of glucose attached together into branching chains. Each of the balls in the bottom diagram represents one molecule of glucose. (Credit: Glycogen by BorisTM. This work has been released into 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 >>

Bbc Bitesize - Higher Biology - Science Of Food Production - Revision 4

Bbc Bitesize - Higher Biology - Science Of Food Production - Revision 4

The human population is increasing and this increases demand for food. Farmers can alter genes, control pests and ensure acceptable well-being to increase yields of plants and livestock. The glucose can be broken down in plant cells by the process of respiration. The chemical energy released by respiration can be used by the plant for cellular activities such as protein synthesis or cell division. Thousands of glucose molecules can be linked together to form the complex carbohydrate starch. Starch is stored inside plant cells as grains. Thousands of glucose molecules can be linked together to form the complex carbohydrate cellulose. Cellulose is a very tough molecule that is used to build the cell wall of plant cells. Glucose is an example of a carbohydrate - it contains the chemical elements carbon, hydrogen and oxygen. Plant cells can convert the sugar into another type of energy storage molecule - fat. Plant cells can also combine sugars with nitrates to make amino acids and use these to produce proteins. Continue reading >>

Connections Of Carbohydrate, Protein, And Lipid Metabolic Pathways

Connections Of Carbohydrate, Protein, And Lipid Metabolic Pathways

Connecting Other Sugars to Glucose Metabolism Sugars, such as galactose, fructose, and glycogen, are catabolized into new products in order to enter the glycolytic pathway. Learning Objectives Identify the types of sugars involved in glucose metabolism Key Takeaways When blood sugar levels drop, glycogen is broken down into glucose -1-phosphate, which is then converted to glucose-6-phosphate and enters glycolysis for ATP production. In the liver, galactose is converted to glucose-6-phosphate in order to enter the glycolytic pathway. Fructose is converted into glycogen in the liver and then follows the same pathway as glycogen to enter glycolysis. Sucrose is broken down into glucose and fructose; glucose enters the pathway directly while fructose is converted to glycogen. disaccharide: A sugar, such as sucrose, maltose, or lactose, consisting of two monosaccharides combined together. glycogen: A polysaccharide that is the main form of carbohydrate storage in animals; converted to glucose as needed. monosaccharide: A simple sugar such as glucose, fructose, or deoxyribose that has a single ring. You have learned about the catabolism of glucose, which provides energy to living cells. But living things consume more than glucose for food. How does a turkey sandwich end up as ATP in your cells? This happens because all of the catabolic pathways for carbohydrates, proteins, and lipids eventually connect into glycolysis and the citric acid cycle pathways. Metabolic pathways should be thought of as porous; that is, substances enter from other pathways, and intermediates leave for other pathways. These pathways are not closed systems. Many of the substrates, intermediates, and products in a particular pathway are reactants in other pathways. Like sugars and amino acids, the catabo 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 >>

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 >>

What Is Anabolism?

What Is Anabolism?

Anabolism is the process by which the body utilizes the energy released by catabolism to synthesize complex molecules. These complex molecules are then utilized to form cellular structures that are formed from small and simple precursors that act as building blocks. Stages of anabolism There are three basic stages of anabolism. Stage 1 involves production of precursors such as amino acids, monosaccharides, isoprenoids and nucleotides. Stage 2 involves activation of these precursors into reactive forms using energy from ATP Stage 3 involves the assembly of these precursors into complex molecules such as proteins, polysaccharides, lipids and nucleic acids. Sources of energy for anabolic processes Different species of organisms depend on different sources of energy. Autotrophs such as plants can construct the complex organic molecules in cells such as polysaccharides and proteins from simple molecules like carbon dioxide and water using sunlight as energy. Heterotrophs, on the other hand, require a source of more complex substances, such as monosaccharides and amino acids, to produce these complex molecules. Photoautotrophs and photoheterotrophs obtain energy from light while chemoautotrophs and chemoheterotrophs obtain energy from inorganic oxidation reactions. Anabolism of carbohydrates In these steps simple organic acids can be converted into monosaccharides such as glucose and then used to assemble polysaccharides such as starch. Glucose is made from pyruvate, lactate, glycerol, glycerate 3-phosphate and amino acids and the process is called gluconeogenesis. Gluconeogenesis converts pyruvate to glucose-6-phosphate through a series of intermediates, many of which are shared with glycolysis. Usually fatty acids stored as adipose tissues cannot be converted to glucose thr Continue reading >>

Can The Human Body Turn Excess Glucose Into Proteins?

Can The Human Body Turn Excess Glucose Into Proteins?

Answered Apr 19, 2016 Author has 8.4k answers and 5.9m answer views No. Glucose is absorbed into our living cells via insulin for instant energy and any excess energy will be first stored in our liver and muscle glycogen then once your glycogen storages are full, they will be converted into fatty acids. Glucose is hydrocarbon chain while amino acids have nitride in the backbone. You can't create nitride out of nowhere. Answered Dec 26, 2017 Author has 1.5k answers and 370.1k answer views Yes. Glucose is the starting point for the synthesis of the nonessential amino acids, which are then incorporated into proteins. A simple pathway to illustrate the point is glucose pyruvate alanine. The last step involves transamination, so you need glucose plus nitrogen from the bodys nitrogen pool. Excess glucose can not be directly converted into protein as it is converted into glycogen and beyond its storage of glycogen in liver and muscles cells into fats. But glucose involved in metabolic pathway indirectly contribute to protein formation. Proteins are made up of amino acids. Amino acids has amino group and a carbon skeleton. During amino acid synthesis amino group for most of amino acid is derived from glutamate but carbon skeletons are derived from commonly available metabolic intermediates of glycolysis, the citric acid cycle, or the pentosr phosphate pathway. The primary carbon sources are glycerate-3-phosphate, pyruvate, PEP , alpha ketoglutarate, oxaloacetate, ribose-5-phosphate, phosphoenolpyruvate and erythrose-4-phosphate. Most of body usable carbohydrates are converted to glucose and glucose undergo glycolysis followed by TCA or Pentose phosphate pathway and above mentioned products are formed during that. The body does to some extent indirectly convert glucose into pro Continue reading >>

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