Outline the two major phases of the pentose phosphate shunt. Regulation of the pentose phosphate pathway in cancer pdf. This pathway is very active in tissues involved in cholesterol and fatty acid liver, adipose tissues, adrenal cortex, mammal glands. In fact as much as 10% of glucose consumption, by erythrocytes, may be mediated by the pentose phosphate pathway. The sequence of reactions are divided into two types. If you continue browsing the site, you agree to the use of cookies on this website. Pentose phosphate pathway and gluconeogenesis study guide by braydenwilky includes 48 questions covering vocabulary, terms and more. Glucose 6p dehydrogenase deficency sexlinked trait cause oxidative stress under certain environmental conditions low levels of glutathione another genetic trait favored in malarial regions distorts surface of red blood cells targets them for destruction anitmalarial drugs cause hemolytic crisis by oxdiative. The oxidative pentose phosphate pathway converts between 15 and 30% of hexose phosphate to glyceraldehyde3 phosphate and co 2 in pea and spinach chloroplasts. Glycolysis, gluconeogenesis, and the pentose phosphate pathway. In the liver, 30% of glucose is metabolized by the pentose phosphate pathway. The pentose phosphate pathway is also called as the phosphogluconate pathway or hexose monophosphate shunt.
The pentose phosphate pathway ppp is also responsible for the production of ribose5 phosphate which is an important part of nucleic acids. The pentose phosphate pathway may be referred to as the pentose phosphate cycle, phosphogluconate pathway, hexose monophosphate cycle, or warburgdickenshorecker shunt. The pentose phosphate pathway is a metabolic pathway parallel to glycolysis which generates nadph and pentoses 5carbon sugars as well as ribose 5 phosphate. Ribose is a constituent of rna, and the related molecule, deoxyribose, is a constituent of dna. Pentose phosphate pathway is an alternative pathway to glycolysis and tca cycle for oxidation of glucose. Glucose6p ribose5p glucose 6phosphate dehydrogenase. The pentose phosphate shunt functions as a source of nadph and ribose 5 phosphate. Which pathway or combination of pathways that are operating at the same time isare capable of. Learn vocabulary, terms, and more with flashcards, games, and other study tools. It generates nadph and pentoses 5carbon sugars as well as ribose 5phosphate, the last one a precursor for the synthesis of nucleotides. Ppt pentose phosphate pathway powerpoint presentation. The pentose phosphate pathway is primarily an anabolic pathway that utilizes the 6 carbons of glucose to generate 5 carbon sugars and reducing equivalents. Pentose phosphate pathway hexose monophosphate shunt.
Nadph can be produced during glucose6p oxidation through a pathway distinct from glycolysis, the pentosephosphate pathway. The pentose phosphate pathway also called the phosphogluconate pathway and the hexose monophosphate shunt is a metabolic pathway parallel to glycolysis. The process of pentose phosphate pathway occurs in the cytoplasm. The pentose phosphate pathway has two main functions generation of nadph. Mcmp 208 biochemistry for pharmaceutical sciences i april. The pentose phosphate pathway ppp, which branches from glycolysis at the first committed step of glucose metabolism, is required for the synthesis of ribonucleotides and is a major source of nadph. Metabolism lecture 5 pentose phosphate pathway restricted for students enrolled in mcb102, uc berkeley, spring 2008 only oxidative phase.
Mcmp 208 biochemistry for pharmaceutical sciences i april 4, 2017. This second process is a complex sequence of reactions that let you change the c3, c4, c5, c6, and c7 pentose sugars to form finally glyceraldehyde3 phosphate and fructose 6 phosphate, which can go directly to glycolysis. Cite two reasons why gluconeogenesis is not the simple reverse of glycolysis. Phosphorylated pentoses are important products of the pentose phosphate pathway, most importantly ribose 5 phosphate r5p, which is used in the synthesis of nucleotides and nucleic acids, and erythrose 4 phosphate e4p, which is used in the synthesis of aromatic amino acids. The nonoxidative phase of the pentose phosphate pathway is initiated when the cell needs more nadph than ribose5 phosphate. Nadph is a carrier of chemical energy in the form of reducing power for reductive syntheses and hydroxylations catalysed by monooxygenases, and some other important reductions. Because the pathway begins and ends with glucose6phosphate, it is a cycle, or shunt. Pentose phosphate pathway hexose monophosphate shunt overview oxidative branch of glucose nonoxidative. A free powerpoint ppt presentation displayed as a flash slide show on id. The pentose phosphate pathway can use any available molecules of glucose6 phosphate, whether they are produced by glycolysis or other methods. Metabolism lecture 5 pentose phosphate pathway restricted for students enrolled in mcb102, uc berkeley, spring 2008 only. What is the pentose phosphate pathway and its significance.
In order to perform its anabolism, a cell needs not only energy atp. Mutant forms of two enzymes of the pentose phosphate pathway have been associated with disease in humans. The oxidative conversion of glucose6phosphate to ribulose 5phosphate and co 2 and. The plastidial pentose phosphate pathway is essential for. It is also known as hexose monophosphate hmp shunt or phosphogluconate pathway. Cellular respiration overview now, we are ready to enter the first of two phases of the pentose phosphate pathway. Nicotinamide adenine dinucleotide phosphate nadp carrying electrons and bonded with a.
Pentose phosphate pathway the medical biochemistry page. A mutation in ribose5 phosphate isomerase rpia, which normally mediates the reversible interconversion of dribulose5 phosphate and ribose5 phosphate, has been associated with a slowly progressive leukoencephalopathy, and mutations in transaldolase 1 taldo1, which normally. It is an alternative route for the metabolism of gl slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. Pentose phosphate pathway generation of nadph and pentoses overview function nadph production reducing power carrier synthetic pathways role as cellular antioxidants. Pentose phosphate pathway starts with glucose and it is a multisteps reaction. In it, glucose becomes the source of nadph, used for antioxidant defense, detoxification, recycling of nutrients like vitamin k and folate, and the anabolic synthesis of fatty acids, cholesterol, neurotransmitters, and nucleotides.
The pentose phosphate pathway and cancer request pdf. Glycolysis, gluconeogenesis, and the pentose phosphate pathway slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. The pentose phosphate pathway ppp is one that many students are confused by. The ppp directs glucose flux to its oxidative branch and produces a reduced form of nicotinamide adenine dinucleotide phosphate nadph, an essential reductant in anabolic processes. The pentose phosphate pathway is an alternative to glycolysis. Pentose phosphate pathway an overview sciencedirect topics. The pentose phosphate pathway ppp is a major pathway for glucose catabolism. The pentose phosphate pathway is primarily catabolic and serves as an alternative glucose oxidizing pathway for the generation of nadph that is required for reductive biosynthetic reactions such as those of cholesterol biosynthesis, bile acid synthesis, steroid hormone biosynthesis, and fatty acid synthesis. It produces nadph which in turn involves in the synthesis of fatty acids that involves about 50% of the nadph molecules. Finally the ppp can also be used to produce glyceraldehyde3 phosphate which can then be fed into the tca and etc cycles allowing for the harvest of energy. Pentose phosphate pathway ppp non oxidative phase conversion of pentose phosphate to glucose 6 phosphate in cell that require high level of nadph for biosynthetic reaction, the ribulose 5p produced in the oxidative phase need to be a turn back in to a glucose 6 phosphate to maintain flux through the glucose 6p dehydrogenase reaction.
Pentose phosphate pathway ppp or hexose monophosphate. Gluconeogenesis, glycogen metabolism, and the pentose. The pentose phosphate pathway is a small, but very important biochemical pathway physicians should be aware of, as, for instance, the metabolic disorder glucose6 phosphate dehydrogenase deficiency g6pd may impart a distinct selective advantage against malaria. The pentose phosphate pathway metabolism of fructose and. Pentose phosphate pathway and gluconeogenesis flashcards. Gluconeogenesis, glycogen metabolism, and the pentose phosphate pathway objectives. The pentose phosphate shunt also known as the hexose monophosphate shunt or the 6phosphogluconate pathway shares the intermediates glyceraldehyde3 phosphate and fructose6 phosphate with the glycolytic pathway.
Perhaps the reason for this is that it does not really have a single direction in which it proceeds, as will be apparent below. Glucose6 phosphate dehydrogenase and a lactonase catalyze the first committed step of the oxidative pentose phosphate pathway which is a strategic control point. The cellular degradation of the simple sugar glucose to yield pyruvic acid and atp as an energy source. Regeneration modes red blood cells glucose 6p dehydrogenase deficency. Regulation of the pentose phosphate pathway by an androgen. The pentose phosphate pathway can also function as an anabolic pathway that utilizes. Resynthesis of glucose6phosphate from ribulose 5phosphate. The pentose phosphate pathway is the major source of nadph in the cytoplasm. It leads to two special products in animal tissues.