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Glucose-1-phosphate
Glucose 1-phosphate (also called Cori ester) is a glucose molecule with a phosphate group on the 1'-carbon. It can exist in either the α- or β-anomeric form. Reactions of α-glucose 1-phosphate Catabolic In glycogenolysis, it is the direct product of the reaction in which glycogen phosphorylase cleaves off a molecule of glucose from a greater glycogen structure. A deficiency of muscle glycogen phosphorylase is known as glycogen storage disease type V (McArdle Disease). To be utilized in cellular catabolism it must first be converted to glucose 6-phosphate by the enzyme phosphoglucomutase in a free equilibrium. One reason that cells form glucose 1-phosphate instead of glucose during glycogen breakdown is that the very polar phosphorylated glucose cannot leave the cell membrane and so is marked for intracellular catabolism. Phosphoglucomutase-1 deficiency is known as glycogen storage disease type 14 (GSD XIV). Anabolic In glycogenesis, free glucose 1-phosphate can also react w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glycogen Phosphorylase
Glycogen phosphorylase is one of the phosphorylase enzymes (). Glycogen phosphorylase catalyzes the rate-limiting step in glycogenolysis in animals by releasing glucose-1-phosphate from the terminal alpha-1,4-glycosidic bond. Glycogen phosphorylase is also studied as a model protein regulated by both reversible phosphorylation and allosteric effects. Mechanism Glycogen phosphorylase breaks up glycogen into glucose subunits (see also figure below): (α-1,4 glycogen chain)n + Pi ⇌ (α-1,4 glycogen chain)n-1 + α-D-glucose-1-phosphate. Glycogen is left with one fewer glucose molecule, and the free glucose molecule is in the form of glucose-1-phosphate. In order to be used for metabolism, it must be converted to glucose-6-phosphate by the enzyme phosphoglucomutase. Although the reaction is reversible in vitro, within the cell the enzyme only works in the forward direction as shown below because the concentration of inorganic phosphate is much higher than that of gluco ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glycogen Storage Disease Type V
Glycogen storage disease type V (GSD5, GSD-V), also known as McArdle's disease, is a metabolic disorder, one of the metabolic myopathies, more specifically a muscle glycogen storage disease, caused by a deficiency of myophosphorylase. Its incidence is reported as one in 100,000, roughly the same as glycogen storage disease type I. The disease was first reported in 1951 by British physician Brian McArdle of Guy's Hospital, London. Signs and symptoms Onset of symptoms and diagnostic delay In the classic phenotype, the onset of this disease is usually noticed in childhood, but often not diagnosed until the third or fourth decade of life, frequently due to misdiagnosis and dismissal of symptoms. The median age of symptom onset is 3 years, with the median diagnostic delay being 29 years. Misdiagnosis is overwhelmingly common, with approximately 90% of patients being misdiagnosed, and approximately 62% receiving multiple misdiagnoses before a correct diagnosis. The prolonged diagno ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glycogen
Glycogen is a multibranched polysaccharide of glucose that serves as a form of energy storage in animals, fungi, and bacteria. It is the main storage form of glucose in the human body. Glycogen functions as one of three regularly used forms of energy reserves, creatine phosphate being for very short-term, glycogen being for short-term and the triglyceride stores in adipose tissue (i.e., body fat) being for long-term storage. Protein, broken down into amino acids, is seldom used as a main energy source except during starvation and glycolytic crisis ''(see bioenergetic systems)''. In humans, glycogen is made and stored primarily in the cells of the liver and skeletal muscle. In the liver, glycogen can make up 5–6% of the organ's fresh weight: the liver of an adult, weighing 1.5 kg, can store roughly 100–120 grams of glycogen. In skeletal muscle, glycogen is found in a low concentration (1–2% of the muscle mass): the skeletal muscle of an adult weighing 70 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phosphoglucomutase
Phosphoglucomutase () is an enzyme that transfers a phosphate group on an α-D-glucose monomer from the 1 to the 6 position in the forward direction or the 6 to the 1 position in the reverse direction. More precisely, it facilitates the interconversion of glucose 1-phosphate and glucose 6-phosphate. Function Role in glycogenolysis After glycogen phosphorylase catalyzes the phosphorolytic cleavage of a glucosyl residue from the glycogen polymer, the freed glucose has a phosphate group on its 1-carbon. This glucose 1-phosphate molecule is not itself a useful metabolic intermediate, but phosphoglucomutase catalyzes the conversion of this glucose 1-phosphate to glucose 6-phosphate (see below for the mechanism of this reaction). Glucose 6-phosphate’s metabolic fate depends on the needs of the cell at the time it is generated. If the cell is low on energy, then glucose 6-phosphate will travel down the glycolytic pathway, eventually yielding two molecules of adenosine tripho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glycogenolysis
Glycogenolysis is the breakdown of glycogen (n) to glucose-1-phosphate and glycogen (n-1). Glycogen branches are catabolized by the sequential removal of glucose monomers via phosphorolysis, by the enzyme glycogen phosphorylase. Mechanism In the muscles, glycogenolysis begins due to the binding of cAMP to phosphorylate kinase, converting the latter to its active form so it can convert phosphorylase b to phosphorylase a, which is responsible for catalyzing the breakdown of glycogen. The overall reaction for the breakdown of glycogen to glucose-1-phosphate is: : glycogen(n residues) + Pi glycogen(n-1 residues) + glucose-1-phosphate Here, glycogen phosphorylase cleaves the bond linking a terminal glucose residue to a glycogen branch by substitution of a phosphoryl group for the α →4linkage. Glucose-1-phosphate is converted to glucose-6-phosphate (which often ends up in glycolysis) by the enzyme phosphoglucomutase. Glucose residues are phosphorolysed from bra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glycogenesis
Glycogenesis is the process of glycogen synthesis or the process of converting glucose into glycogen in which glucose molecules are added to chains of glycogen for storage. This process is activated during rest periods following the Cori cycle, in the liver, and also activated by insulin in response to high glucose levels. Steps * Glucose is converted into glucose 6-phosphate by the action of glucokinase or hexokinase with conversion of ATP to ADP. * Glucose-6-phosphate is converted into glucose-1-phosphate by the action of phosphoglucomutase, passing through the obligatory intermediate glucose-1,6-bisphosphate. * Glucose-1-phosphate is converted into UDP-glucose by the action of the enzyme UDP-glucose pyrophosphorylase. Pyrophosphate is formed, which is later hydrolysed by pyrophosphatase into two phosphate molecules. * The enzyme glycogenin is needed to create initial short glycogen chains, which are then lengthened and branched by the other enzymes of glycogene ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gerty Cori
Gerty Theresa Cori (; August 15, 1896 – October 26, 1957) was a Bohemian-Austrian and American biochemist who in 1947 was the third woman to win a Nobel Prize in science, and the first woman to be awarded the Nobel Prize in Physiology or Medicine, for her role in the "discovery of the course of the catalytic conversion of glycogen". Cori was born in Prague, the capital of Bohemia within the Austro-Hungarian Empire. Growing up at a time when women were marginalized and allowed few educational opportunities, she gained admittance to medical school, where she met her future husband Carl Ferdinand Cori in an anatomy class. Upon their graduation in 1920, they married. Because of deteriorating conditions in Europe, the couple emigrated to the United States in 1922. Gerty Cori continued her early interest in medical research, collaborating in the laboratory with Carl. She published research coauthored with her husband, as well as publishing singly. Unlike her husband, she had diff ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glycogen Storage Disease
A glycogen storage disease (GSD, also glycogenosis and dextrinosis) is a metabolic disorder caused by a deficiency of an enzyme or transport protein affecting glycogen synthesis, glycogen breakdown, or glycolysis, glucose breakdown, typically in muscles and/or liver cells. GSD has two classes of cause: genetic and environmental. Genetic GSD is caused by any Inborn errors of carbohydrate metabolism, inborn error of carbohydrate metabolism (genetically defective enzymes or transport proteins) involved in these processes. In livestock, environmental GSD is caused by Substance intoxication, intoxication with the alkaloid castanospermine. However, not every inborn error of carbohydrate metabolism has been assigned a GSD number, even if it is known to affect the muscles or liver. For example, phosphoglycerate kinase deficiency (gene PGK1) has a myopathic form. Also, Fanconi–Bickel syndrome, Fanconi-Bickel syndrome (gene SLC2A2) and Danon disease (gene LAMP2) were declassed as GSDs d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uridine Triphosphate
Uridine-5′-triphosphate (UTP) is a pyrimidine nucleoside triphosphate, consisting of the organic base uracil linked to the 1′ carbon of the ribose sugar, and esterified with tri-phosphoric acid at the 5′ position. Its main role is as substrate for the synthesis of RNA during transcription. UTP is the precursor for the production of CTP via CTP synthetase. UTP can be biosynthesized from UDP by Nucleoside Diphosphate Kinase after using the phosphate group from ATP. UDP + ATP ⇌ UTP + ADP; both UTP and ATP are energetically equal. The homologue in DNA is thymidine triphosphate (TTP or dTTP). UTP also has a deoxyribose form (dUTP). Role in metabolism UTP also has the role of a source of energy or an activator of substrates in metabolic reactions, like that of ATP, but more specific. When UTP activates a substrate (such as glucose-1-phosphate), UDP-glucose is formed and inorganic phosphate is released. UDP-glucose enters the synthesis of glycogen. UTP is used in the meta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glycogen Synthase
Glycogen synthase (UDP-glucose-glycogen glucosyltransferase) is a key enzyme in glycogenesis, the conversion of glucose into glycogen. It is a glycosyltransferase () that catalyses the reaction of UDP-glucose and (1,4--D-glucosyl)n to yield UDP and (1,4--D-glucosyl)n+1. Structure Much research has been done on glycogen degradation through studying the structure and function of glycogen phosphorylase, the key regulatory enzyme of glycogen degradation. On the other hand, much less is known about the structure of glycogen synthase, the key regulatory enzyme of glycogen synthesis. The crystal structure of glycogen synthase from ''Agrobacterium tumefaciens'', however, has been determined at 2.3 A resolution. In its asymmetric form, glycogen synthase is found as a dimer, whose monomers are composed of two Rossmann-fold domains. This structural property, among others, is shared with related enzymes, such as glycogen phosphorylase and other glycosyltransferases of the GT-B super ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organophosphates
In organic chemistry, organophosphates (also known as phosphate esters, or OPEs) are a class of organophosphorus compounds with the general structure , a central phosphate molecule with alkyl or aromatic substituents. They can be considered as esters of phosphoric acid. Organophosphates are best known for their use as pesticides. Like most functional groups, organophosphates occur in a diverse range of forms, with important examples including key biomolecules such as DNA, RNA and ATP, as well as many insecticides, herbicides, nerve agents and flame retardants. OPEs have been widely used in various products as flame retardants, plasticizers, and performance additives to engine oil. The low cost of production and compatibility to diverse polymers made OPEs to be widely used in industry including textile, furniture, electronics as plasticizers and flame retardants. These compounds are added to the final product physically rather than by chemical bond. Due to this, OPEs leak int ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pentose Phosphate Pathway
The pentose phosphate pathway (also called the phosphogluconate pathway and the hexose monophosphate shunt or HMP shunt) is a metabolic pathway parallel to glycolysis. It generates NADPH and pentoses (five-carbon sugars) as well as ribose 5-phosphate, a precursor for the synthesis of nucleotides. While the pentose phosphate pathway does involve oxidation of glucose, its primary role is anabolic rather than catabolic. The pathway is especially important in red blood cells (erythrocytes). The reactions of the pathway were elucidated in the early 1950s by Bernard Horecker and co-workers. There are two distinct phases in the pathway. The first is the oxidative phase, in which NADPH is generated, and the second is the non-oxidative synthesis of five-carbon sugars. For most organisms, the pentose phosphate pathway takes place in the cytosol; in plants, most steps take place in plastids. Like glycolysis, the pentose phosphate pathway appears to have a very ancient evolutionary ori ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
