pentose phosphate pathway

pathway

[path´wa] a course usually followed. In neurology, the nerve structures through which a sensory impression is conducted to the cerebral cortex (afferent pathway), or through which an impulse passes from the brain to the skeletal musculature (efferent pathway). Also used alone to indicate a sequence of reactions that convert one biological material to another (metabolic pathway).accessory pathway (accessory conduction pathway) extra muscle tissue between the atrium and ventricle that bypasses all or part of the normal system" >conduction system. When the ventricles are activated prematurely via this pathway, initial forces are slow, producing the delta wave of wolff-parkinson-white syndrome, and preexcitation is said to exist; the delta wave causes the PR interval to shorten and the QRS interval to broaden.alternative complement pathway see complement.amphibolic pathway a group of metabolic reactions with a dual function, providing small metabolites for further catabolism to end products or for use as precursors in synthetic, anabolic reactions. The cycle" >tricarboxylic acid cycle is an example. See also anabolism and catabolism.biosynthetic pathway the sequence of enzymatic steps in the synthesis of a specific end-product in a living organism.classical complement pathway see complement.coagulation p's see common p. of coagulation, extrinsic p. of coagulation, and intrinsic p. of coagulation.common pathway of coagulation the steps in the mechanism of coagulation (see clotting) from the activation of factor x through the conversion of fibrinogen to fibrin. See also pathway of coagulation" >intrinsic pathway of coagulation and pathway of coagulation" >extrinsic pathway of coagulation.concealed accessory pathway an pathway" >accessory pathway that has only retrograde conduction; thus its PR and QRS complexes are normal on the electrocardiogram, but there is a tendency to develop premature tachycardia" >supraventricular tachycardia. If fibrillation" >atrial fibrillation develops, conduction will proceed across the atrioventricular node.Embden-Meyerhof pathway the series of enzymatic reactions in the anaerobic conversion of glucose to lactic acid, resulting in energy in the form of adenosine triphosphate (ATP).extrinsic pathway of coagulation the mechanism that produces fibrin following tissue injury, beginning with formation of an activated complex between factor" >tissue factor and factor vii and leading to activation of factor x, which induces the reactions of the pathway of coagulation" >common pathway of coagulation. See also pathway of coagulation" >intrinsic pathway of coagulation.final common pathway 1. the motor neurons by which nerve impulses from many central sources pass to a muscle or gland in the periphery.2. any mechanism by which several independent effects exert a common influence.intrinsic pathway of coagulation a sequence of reactions leading to fibrin formation, beginning with the contact activation of factor xii. This is followed by the sequential activation of factors xi and ix, which results in the activation of factor x. Activated factor X (factor Xa) initiates the pathway of coagulation" >common pathway of coagulation. See also pathway of coagulation" >extrinsic pathway of coagulation.pentose phosphate pathway a pathway of hexose oxidation in which glucose-6-phosphate undergoes two successive oxidations by NADP, the final forming a pentose phosphate.

pen·tose phos·phate path·way

a secondary pathway for the oxidation of d-glucose (not occurring in skeletal muscle), generating reducing power (NADPH) in the cytoplasm and synthesizing pentoses and a few other sugars. It also provides a means of converting pentoses and certain other sugars into intermediates of the glycolytic pathway. It proceeds from d-glucose 6-phosphate to d-ribulose and d-ribose phosphates, thence (with d-xylulose 5-phosphate) to d-sedoheptulose 7-phosphate and d-glyceraldehyde 3-phosphate; carbon dioxide is released in the gluconate-ribulose step. In plants, it participates in the formation of d-glucose from carbon dioxide in the dark reactions of photosynthesis. This pathway is defective in certain inherited diseases, for example, glucose-6-phosphate dehydrogenase deficiency. Synonym(s): Dickens shunt, hexose monophosphate pathway, hexose monophosphate shunt, pentose monophosphate shunt, pentose phosphate cycle, phosphogluconate pathway, Warburg-Dickens-Horecker shunt, Warburg-Lipmann-Dickens-Horecker shunt

pen·tose phos·phate path·way

(pen'tōs fos'fāt path'wā) A secondary pathway for the oxidation of d-glucose (not occurring in skeletal muscle), generating reducing power (NADPH) in the cytoplasm outside the mitochondria and synthesizing pentoses and a few other sugars. This pathway is defective in certain inherited diseases (e.g., glucose-6-phosphate dehydrogenase deficiency).
Synonym(s): Dickens shunt.

pentose phosphate pathway (PPP), pentose phosphate shunt, hexose monophosphate shunt or phosphogluronate pathway

a PATHWAY for the metabolism of glucose. PPP is particularly important in animal cells where it functions as an alternative to GLYCOLYSIS and the KREBS CYCLE, although both mechanisms occur together.

In the PPP, glucose (a hexose sugar) in the form of glucose phosphate molecules, is oxidized by the removal of hydrogen and decarboxylated, producing pentose sugars, carbon dioxide and hydrogen atoms, which are transferred to the coenzyme NADP to form NADPH₂. In a second stage the pentose sugars are rearranged to produce hexose again, although in a smaller quantity than at the start. Unlike NADH, NADPH is not involved in producing ATP via an ELECTRON TRANSPORT SYSTEM, but transfers hydrogen atoms and electrons to sites where molecules are being assembled.

The NADPH2 molecules are particularly active in cells carrying out fat metabolism, such as adipose tissue, liver, adrenal cortex, mammary gland tissue.

Dickens,

Frank, English biochemist, 1899–. Dickens shunt - a secondary pathway for the oxidation of d-glucose (not occurring in skeletal muscle), generating reducing power in the cytoplasm outside the mitochondria and synthesizing pentoses and a few other sugars. Synonym(s): pentose phosphate pathway; Warburg-Lipmann-Dickens-Horecker shuntWarburg-Lipmann-Dickens-Horecker shunt - Synonym(s): Dickens shunt

单词	pentose phosphate pathway
释义	pentose phosphate pathway pentose phosphate pathway n (Biochemistry) a sequence of metabolic reactions by which NADPH is synthesized, together with ribose phosphate, part of the synthesis of nucleic acids pentose phosphate pathway pentose phosphate pathway [′pen‚tōs ′fäs‚fāt ′path‚wā] (biochemistry) A pathway by which glucose is metabolized or transformed in plants and microorganisms; glucose-6-phosphate is oxidized to 6-phosphogluconic acid, which then undergoes oxidative decarboxylation to form ribulose-5-phosphate, which is ultimately transformed to fructose-6-phosphate. pentose phosphate pathway pathway [path´wa] a course usually followed. In neurology, the nerve structures through which a sensory impression is conducted to the cerebral cortex (afferent pathway), or through which an impulse passes from the brain to the skeletal musculature (efferent pathway). Also used alone to indicate a sequence of reactions that convert one biological material to another (metabolic pathway).accessory pathway (accessory conduction pathway) extra muscle tissue between the atrium and ventricle that bypasses all or part of the normal system" >conduction system. When the ventricles are activated prematurely via this pathway, initial forces are slow, producing the delta wave of wolff-parkinson-white syndrome, and preexcitation is said to exist; the delta wave causes the PR interval to shorten and the QRS interval to broaden.alternative complement pathway see complement.amphibolic pathway a group of metabolic reactions with a dual function, providing small metabolites for further catabolism to end products or for use as precursors in synthetic, anabolic reactions. The cycle" >tricarboxylic acid cycle is an example. See also anabolism and catabolism.biosynthetic pathway the sequence of enzymatic steps in the synthesis of a specific end-product in a living organism.classical complement pathway see complement.coagulation p's see common p. of coagulation, extrinsic p. of coagulation, and intrinsic p. of coagulation.common pathway of coagulation the steps in the mechanism of coagulation (see clotting) from the activation of factor x through the conversion of fibrinogen to fibrin. See also pathway of coagulation" >intrinsic pathway of coagulation and pathway of coagulation" >extrinsic pathway of coagulation.concealed accessory pathway an pathway" >accessory pathway that has only retrograde conduction; thus its PR and QRS complexes are normal on the electrocardiogram, but there is a tendency to develop premature tachycardia" >supraventricular tachycardia. If fibrillation" >atrial fibrillation develops, conduction will proceed across the atrioventricular node.Embden-Meyerhof pathway the series of enzymatic reactions in the anaerobic conversion of glucose to lactic acid, resulting in energy in the form of adenosine triphosphate (ATP).extrinsic pathway of coagulation the mechanism that produces fibrin following tissue injury, beginning with formation of an activated complex between factor" >tissue factor and factor vii and leading to activation of factor x, which induces the reactions of the pathway of coagulation" >common pathway of coagulation. See also pathway of coagulation" >intrinsic pathway of coagulation.final common pathway 1. the motor neurons by which nerve impulses from many central sources pass to a muscle or gland in the periphery.2. any mechanism by which several independent effects exert a common influence.intrinsic pathway of coagulation a sequence of reactions leading to fibrin formation, beginning with the contact activation of factor xii. This is followed by the sequential activation of factors xi and ix, which results in the activation of factor x. Activated factor X (factor Xa) initiates the pathway of coagulation" >common pathway of coagulation. See also pathway of coagulation" >extrinsic pathway of coagulation.pentose phosphate pathway a pathway of hexose oxidation in which glucose-6-phosphate undergoes two successive oxidations by NADP, the final forming a pentose phosphate. pen·tose phos·phate path·way a secondary pathway for the oxidation of d-glucose (not occurring in skeletal muscle), generating reducing power (NADPH) in the cytoplasm and synthesizing pentoses and a few other sugars. It also provides a means of converting pentoses and certain other sugars into intermediates of the glycolytic pathway. It proceeds from d-glucose 6-phosphate to d-ribulose and d-ribose phosphates, thence (with d-xylulose 5-phosphate) to d-sedoheptulose 7-phosphate and d-glyceraldehyde 3-phosphate; carbon dioxide is released in the gluconate-ribulose step. In plants, it participates in the formation of d-glucose from carbon dioxide in the dark reactions of photosynthesis. This pathway is defective in certain inherited diseases, for example, glucose-6-phosphate dehydrogenase deficiency. Synonym(s): Dickens shunt, hexose monophosphate pathway, hexose monophosphate shunt, pentose monophosphate shunt, pentose phosphate cycle, phosphogluconate pathway, Warburg-Dickens-Horecker shunt, Warburg-Lipmann-Dickens-Horecker shunt pen·tose phos·phate path·way (pen'tōs fos'fāt path'wā) A secondary pathway for the oxidation of d-glucose (not occurring in skeletal muscle), generating reducing power (NADPH) in the cytoplasm outside the mitochondria and synthesizing pentoses and a few other sugars. This pathway is defective in certain inherited diseases (e.g., glucose-6-phosphate dehydrogenase deficiency). Synonym(s): Dickens shunt. pentose phosphate pathway (PPP), pentose phosphate shunt, hexose monophosphate shunt or phosphogluronate pathway a PATHWAY for the metabolism of glucose. PPP is particularly important in animal cells where it functions as an alternative to GLYCOLYSIS and the KREBS CYCLE, although both mechanisms occur together. In the PPP, glucose (a hexose sugar) in the form of glucose phosphate molecules, is oxidized by the removal of hydrogen and decarboxylated, producing pentose sugars, carbon dioxide and hydrogen atoms, which are transferred to the coenzyme NADP to form NADPH₂. In a second stage the pentose sugars are rearranged to produce hexose again, although in a smaller quantity than at the start. Unlike NADH, NADPH is not involved in producing ATP via an ELECTRON TRANSPORT SYSTEM, but transfers hydrogen atoms and electrons to sites where molecules are being assembled. The NADPH2 molecules are particularly active in cells carrying out fat metabolism, such as adipose tissue, liver, adrenal cortex, mammary gland tissue. Dickens, Frank, English biochemist, 1899–. Dickens shunt - a secondary pathway for the oxidation of d-glucose (not occurring in skeletal muscle), generating reducing power in the cytoplasm outside the mitochondria and synthesizing pentoses and a few other sugars. Synonym(s): pentose phosphate pathway; Warburg-Lipmann-Dickens-Horecker shuntWarburg-Lipmann-Dickens-Horecker shunt - Synonym(s): Dickens shunt AcronymsSeePPPThesaurusSeepathway
随便看	rating him above rating him as rating him at rating him below rating himself above rating himself as rating himself at rating him with rating information book rating & investment information, inc. rating maintenance phase rating maintenance plan rating method code rating nut rating of aggression against people and/or property rating of global stock investment rating of medication influences rating of perceived breathing difficulty rating of perceived breathlessness rating of perceived exertion rating of perceived pain rating organization rating organizations rating pending rating point