The use of high energy compounds in cellular metabolism Fig. Structure of the coen-zyme and high energy com-pound Acetyl-coenzyme A (CoA) Are they long-term or short-term storage devices?Ai d lActivated acyl groupsStryer, Biochemistry, 4thed., 1995, FreemanATP and NADPH are the sources of free energy for biosynthetic reactions.Voet, Fundamentals, 3rdFigure 14-2ATP and ADP availability control cellular metabolic activityThe structure of ATP indicating its relationship to ADP, AMP, and adenosineadenosine.Voet, Fundamentals, 3rdPage 380The flow of phosphoryl groups from “high-energy” phosphate donors, via the ATP–ADP system, to “low-energy” phosphate acceptors.Voet, Fundamentals, 3rdFig 4.18Voet, Fundamentals, 3rdPages 465, 466Voet, Fundamentals, 3rdOxidation – reduction Fig. Generic redox reaction mechanism catalyzed by enzymes with NAD as cofactorReducing power is the fundamental energy source used for biosynthesisReducing power is the fundamental energy source used for biosynthesis and production of universal chemical energy (phosphoryl transfer potential) in form of ATPM.C. McMurray, Essentials of human metabolism, 2nded., 1983, Harper-RowVoet, Fundamentals, 3rdFigure 11-4Oxidation-reduction reactions are coupled half-reactions in an electrochemical cellElectron flowIon flowΔG = -nFΔEVoet, Fundamentals, 3rdReduction Oxidation(F Faraday constant; E redox potential; n number of charges)Fig 14.14When coupling half-reactions, the one with the more negative redox t ti l E ill t l tpotential E will act as electron donor; e.g. NADH oxidation to NAD can drive the pyruvate reduction to lactate (fermentation)NADH oxidation to NAD can drive the reduction of O2to waterVoet, Fundamentals, 3rdLactic acid fermentation, a typical dehydrogenase reactionNADH + H++ Pyruvate ' NAD++ LactateNAD++ 2H+ + 2e-'NADH + H+Eo' = -0.32V Pyruvate + 2H++ 2e-' Lactate Eo'= -0.19V KEGG ENTRY EC 1.1.1.27 NAME L-Lactate dehydrogenase Lactic acid dehydrogenase CLASS Oxidoreductases ActingontheCH-OH group of donors Acting on the CH-OH group of donors With NAD+ or NADP+ as acceptor SYSNAME (S)-Lactate:NAD+ oxidoreductase REACTION (S)-Lactate + NAD+ = Pyruvate + NADH SUBSTRATE (S)-Lactate (S)-2-Hydroxymonocarboxylic acid NAD+ PRODUCT Pyruvate NADH PRODUCT Pyruvate NADH COMMENT Also oxidizes other (S)-2-hydroxy-monocarboxylic acids. NADP+ also acts, more slowly, with the animal, but not the bacterial, enzyme. PATHWAY PATH: MAP00010 Glycolysis / Gluconeogenesis PATH: MAP00272 Cysteine metabolism y PATH: MAP00620 Pyruvate metabolism PATH: MAP00640 Propanoate metabolismADP (color) is a general adapter part of coenzymes in energy metabolism; the active component is shown in grey.Stryer, Biochemistry, 4thed., 1995, FreemanCellular organization and control of metabolic pathwaysVoet, Fundamentals, 3rdBox 14.1Anabolic and catabolic reactions are often not catalyzed by the same tf tienzyme or set of reactionsVoet, Fundamentals, 3rdPage 458Pathways are controlled by feed-back inhibitionVoet, Fundamentals, 3rdPage 458Sets of pathways are compartmentalized within organelles and cellsVoet, Fundamentals, 3rdEnergy Charge Pathway regulation is linked to energy availability 0if ll AMPATP + ½ADP ⎯⎯⎯⎯⎯⎯⎯⎯ ATP + ADP + AMP energy availability 0 if all AMP 1 if all ATP ½ if all ADP Fig. 17-16, Stryer, Biochemistry, 4thed., 1995,
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