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newlecture14 - 18-1Fatty Acids and EnergyFatty Acids and...

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Unformatted text preview: 18-1Fatty Acids and EnergyFatty Acids and EnergyFatty acids in the form of triacylglycerolsrepresent the principal way to store energy for most organismstheir carbon chains are in a highly reduced formMeans FA breakdown results in LOTS of NADHthe energy yield per gram of fatty acid oxidized is greaterthan that per gram of carbohydrate oxidizedC6H1 2O6 + 6 O2CH3( CH2)14COOH + 2 3 O26 CO2 + 6 H2O1 6 CO2 + 1 6 H2O -15.9 -38.9Palmitic acidGlucoseEnergy(kJmol-1)18-2Hydrolysis of Glycerol EstersHydrolysis of Glycerol EstersA triacylglycerolCH2O-CROOCH2O-CRRCO-RC-OCHH2OGlycerolLipasesOPhospholipasesA glycerylphosphoryl-cholineH2ORe-useOxidationA phosphatidyl cholineOCH2O-CROCH2O- POCH2CH2N( CH3)3RC-OCHOO-O+freefreefattyfattyacidacidthis breakdown occurs in the cytoplasmthis breakdown occurs in the cytoplasm18-3PhospholipasesPhospholipasesDifferent phospholipases act at different sitesCH2O- C- R2OOCH2O- P- O- R'R1- C- O- CHO-OA1A2CDspider spider venomvenominvolved ininvolved insignal transductionsignal transductionA siteA siteB siteB siteC siteC site18-4Activation of Fatty AcidsActivation of Fatty AcidsStep 1:RCO-O+ATP+PPiRC- AMPO+CoA-SH+AMPRC-AMPStep 2:RCO-O+ATP+CoA-SHRC-SCoA+AMP+ PPiacyl-CoAsynthetaseOORC-SCoAOAcyl adenylateintermediateAn acyl-CoAreleasedreleasedby lipaseby lipaseinitial energyinitial energyinvestmentinvestmentequivalent toequivalent to2 ATP used!2 ATP used!18-5Transport of Acyl-CoATransport of Acyl-CoAthe acyl-CoAcan cross the outer mitochondrial membrane,but not the inner membranethe acyl group needs to be transferred to carnitine (by carnitine palmitoyltransferase) to be carried across the inner mitochondrial membrane (by carnitine translocase)The acyl group is then transferred to mitochondrial CoA-SHCH2N( CH3)3CHCH2COO-RC- SCoAHOO+CH2N( CH3)3CHCH2COO-RCOOHS-CoACarnitineAn acyl-carnitine+++18-6-Oxidation--Oxidation-fatty acid breakdownfatty acid breakdown-Oxidation-Oxidation::a series of 4 enzyme-catalyzedreactions that cleaves carbon atoms twoat a time from the carboxyl end of a fatty acid...
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newlecture14 - 18-1Fatty Acids and EnergyFatty Acids and...

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