lecture11 - 16-1The Citric Acid CycleThe Citric Acid...

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Unformatted text preview: 16-1The Citric Acid CycleThe Citric Acid CycleThree processes play central roles in aerobicmetabolismCitric acid cycle (TCA cycle, Krebs cycle) Know all structures!Electron transport chainOxidative phosphorylationMetabolism:the chemical changes in living cells by which energy is provided for vital processes and activities and new material is assimilated, consists ofcatabolism:catabolism:the oxidative breakdown of nutrientsanabolism:anabolism:the reductive synthesis of biomoleculesThe citric acid cycle is amphibolicamphibolic; that is, it plays a role in BOTHcatabolism and anabolism16-2The Citric Acid Cycle: The Citric Acid Cycle: overviewoverviewPyruvateAcetyl-CoAGDPGTPFADFADH2NAD+NADHNAD+NADHCO2NAD+NADHCO2Citric acidcycle(8 steps)Coenzyme ANAD+NADHResponsible for Responsible for producing NADH producing NADH that is used for that is used for ATP production by ATP production by electron transportelectron transportRemember, for Remember, for every glucose, this every glucose, this cycle occurs twice!cycle occurs twice!16-3Pyruvate to Acetyl-CoAPyruvate to Acetyl-CoAOxidation by NAD+and formation of a thioester+2+CH3CCOO-+NAD+CoA-SH +CH3C-SCoA +CO2pyruvatedehydrogenasecomplexPyruvateCoenzyme AAcetyl-CoAOO+NADHFirst NADH producedFirst NADH producedin TCA cycle!in TCA cycle!made up ofmade up of5 enzymes5 enzymes16-4The Citric Acid CycleThe Citric Acid CycleStep 1: condensationof acetyl-CoAwith oxaloacetate; G = -32.8 kJmol-1(results fromhigh energy thioester bond)citrate synthaseis an allostericenzyme, inhibitedby NADH, ATP, and succinyl-CoACH3C-SCoAAcetyl-CoAC-COO-CH2-COO-Oxaloacetate+C-COO-HOCH2-COO-CH2-COO-+CoA-S HCoenzyme AcitratesynthaseCitrateOOcondensation refers tocondensation refers tonew C-C bond formationnew C-C bond formation16-5The Citric Acid CycleThe Citric Acid CycleStep 2: dehydration and rehydration gives isocitrate; catalyzed by aconitaseC-COO-HOCH2-COO-CH2-COO-CitrateC-COO-CH2-COO-C-COO-HCH- COO-CH2-COO-AconitateHOIsocitrateCH- COO-example of an isomerizationexample of an isomerizationH2OH2O16-6The Citric Acid CycleThe Citric Acid CycleStep 3: oxidation of isocitratefollowed by decarboxylationisocitrate dehydrogenase...
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lecture11 - 16-1The Citric Acid CycleThe Citric Acid...

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