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The game of the pentose phosphate cycle. 1985

E Meléndez-Hevia, and A Isidoro

Sugar rearrangement in the pentose phosphate cycle for transformation of six pentoses into five hexoses is analysed by abstraction to a mathematical model consisting of the resolution of a logical mathematical game of optimization. In the model, the problem is to arrive at five boxes containing six balls each, having started with six boxes containing five balls each, where boxes simulate the sugars and balls simulate the carbons in each. This is achieved by means of transferring two or three balls from any box to any other in each step, according to transketolase and transaldolase (or aldolase) mechanisms which account for sugar interconversions in the living cell. A hypothesis of simplicity is imposed in order to arrive at the objective with the least number of steps and with the least number of balls in the intermediary boxes. A symmetrical solution is obtained, demonstrating that this is the simplest solution, which is the procedure carried out by biological systems. The same treatment is applied for sugar rearrangement in the non-oxidative phase of the Calvin cycle in photosynthesis and the analysis of the "L-type" of pentose phosphate cycle is also treated, obtaining similar solutions in both cases, which allow us to make some physiological reflections.

UI MeSH Term Description Entries
D008433 Mathematics The deductive study of shape, quantity, and dependence. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed) Mathematic
D008954 Models, Biological Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment. Biological Model,Biological Models,Model, Biological,Models, Biologic,Biologic Model,Biologic Models,Model, Biologic
D010427 Pentose Phosphate Pathway An oxidative decarboxylation process that converts GLUCOSE-6-PHOSPHATE to D-ribose-5-phosphate via 6-phosphogluconate. The pentose product is used in the biosynthesis of NUCLEIC ACIDS. The generated energy is stored in the form of NADPH. This pathway is prominent in tissues which are active in the synthesis of FATTY ACIDS and STEROIDS. Hexose Monophosphate Shunt,Pentose Phosphate Shunt,Pentose Shunt,Pentosephosphate Pathway,Pentose-Phosphate Pathway,Pentosephosphate Shunt,Hexose Monophosphate Shunts,Pathway, Pentose Phosphate,Pathway, Pentose-Phosphate,Pathway, Pentosephosphate,Pathways, Pentose Phosphate,Pathways, Pentose-Phosphate,Pathways, Pentosephosphate,Pentose Phosphate Pathways,Pentose Phosphate Shunts,Pentose Shunts,Pentose-Phosphate Pathways,Pentosephosphate Pathways,Pentosephosphate Shunts,Shunt, Hexose Monophosphate,Shunt, Pentose,Shunt, Pentose Phosphate,Shunt, Pentosephosphate,Shunts, Hexose Monophosphate,Shunts, Pentose,Shunts, Pentose Phosphate,Shunts, Pentosephosphate
D010788 Photosynthesis The synthesis by organisms of organic chemical compounds, especially carbohydrates, from carbon dioxide using energy obtained from light rather than from the oxidation of chemical compounds. Photosynthesis comprises two separate processes: the light reactions and the dark reactions. In higher plants; GREEN ALGAE; and CYANOBACTERIA; NADPH and ATP formed by the light reactions drive the dark reactions which result in the fixation of carbon dioxide. (from Oxford Dictionary of Biochemistry and Molecular Biology, 2001) Calvin Cycle,Calvin-Benson Cycle,Calvin-Benson-Bassham Cycle,Carbon Fixation, Photosynthetic,Reductive Pentose Phosphate Cycle,Dark Reactions of Photosynthesis,Calvin Benson Bassham Cycle,Calvin Benson Cycle,Cycle, Calvin,Cycle, Calvin-Benson,Cycle, Calvin-Benson-Bassham,Photosynthesis Dark Reaction,Photosynthesis Dark Reactions,Photosynthetic Carbon Fixation
D005634 Fructose-Bisphosphate Aldolase An enzyme of the lyase class that catalyzes the cleavage of fructose 1,6-biphosphate to form dihydroxyacetone phosphate and glyceraldehyde 3-phosphate. The enzyme also acts on (3S,4R)-ketose 1-phosphates. The yeast and bacterial enzymes are zinc proteins. (Enzyme Nomenclature, 1992) E.C. 4.1.2.13. Aldolase,Fructosediphosphate Aldolase,Aldolase A,Aldolase B,Aldolase C,Fructose 1,6-Bisphosphate Aldolase,Fructose 1,6-Bisphosphate Aldolase, Class II,Fructose 1-Phosphate Aldolase,Fructose Biphosphate Aldolase,Fructosemonophosphate Aldolase,1,6-Bisphosphate Aldolase, Fructose,Aldolase, Fructose 1,6-Bisphosphate,Aldolase, Fructose 1-Phosphate,Aldolase, Fructose Biphosphate,Aldolase, Fructose-Bisphosphate,Aldolase, Fructosediphosphate,Aldolase, Fructosemonophosphate,Fructose 1 Phosphate Aldolase,Fructose 1,6 Bisphosphate Aldolase,Fructose Bisphosphate Aldolase
D014153 Transaldolase An enzyme of the transferase class that catalyzes the reaction sedoheptulose 7-phosphate and D-glyceraldehyde 3-phosphate to yield D-erythrose 4-phosphate and D-fructose phosphate in the PENTOSE PHOSPHATE PATHWAY. (Dorland, 27th ed) EC 2.2.1.2. Transaldolase B
D014174 Transketolase An enzyme of the transferase class that catalyzes the conversion of sedoheptulose 7-phosphate and D-glyceraldehyde 3-phosphate to D-ribose 5-phosphate and D-xylulose 5-phosphate in the PENTOSE PHOSPHATE PATHWAY. (Dorland, 27th ed) EC 2.2.1.1. Apotransketolase,Glycolaldehydetransferase

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