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44 Cards in this Set
- Front
- Back
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TCA Cycle |
tricarboxylic acid cycle citric acid cycle Krebs cycle |
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oxidation of glucose to co2 |
24 electron oxidation feed into electorn transport pathway |
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hans krebs |
pyruvate from glycolysis oxidative decarboxylated to acetyl CoA acetate degraded to co2 in tca some ATP made, more NADH is made that goes to electron transport |
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acetate to 2 co2 |
most oxidized form point of TCA |
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possibilities of TCA cycle |
1- cleave between C alpha and Beta to carbonyl (only aldolase) 2- alpha cleavage of alpha-hydroxyketone these ways to cleave C-C bonds dont work for acetate bc no beta C, and need hydroxylation of acetate that is NOT favorable |
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how to cleave better |
condense acetate with oxalacetate then Beta cleave this makes CO2 |
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1st rxn |
pyruvate enter mitochondria oxidative dehydrogenase by pyruvate dehydrogenase complex- noncovalent of 3 enzymes need 5 coenzymes |
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rxn mechanism of complex |
1- pyruvate loses co2 to HETPP 2- hydroxyethyl to lipoic acid 3- acetyl group to CoA
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pyruvate loses CO2 |
add in TPP- thiamine pyrophosphate ch3-ch-Oh-TPP |
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HETPP on lipoic acid |
lose TPP ch3-choh on lipoic acid thioester!! reduced S-S to -S and SH
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transfer to CoASH |
transfer to another thioester have to oxidized lipoic acid- get NADH!! use FAD- bc lipoic acid 1 e and NADH is 2 e FAD is 1 and 2 e- |
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functions of thiamine + ATP |
TPP assists decarboxylation of a-keto acid form and cleave a-hydroxy ketones O O CH3- C(a)-CO- |
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Coenzyme A |
reactive sulfhydryl 1- activation acyl groups for nuclephilic attack 2- active alpha- H of acyl group to abstract proton |
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lipoic acid |
couple acyl-group transfer and electron transfer during oxidation and decarboxylation of a-keto acids amide bond with e-NH2 of lysine chain when on ENZYMES |
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first 3 steps |
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citrate synthase rxn |
C(a) of acetyl group in acetyl-CoA is acidic and deprotonated (-)CH2-CO-S-CoA carbanion is STRONG nucleophile attack C(a) carbonyl of oxaloacetate= citryl CoA thioester hydrolysis= citrate large G rxn- site of regulation |
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citrate |
poor to oxidize aconitase- isomerize it to isocitrate, use Fe-S cluster so secondary OH can be oxidized (rather than tertiary) removes pro-R H |
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fluoroacetate blocks the TCA cycle |
poisonous inhibit aconitase makes fluorocitrate |
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isocitrate to a-ketoglutarate |
1st oxidative decarboxylation in cycle 1st- hydride removal = NADH on C2 of alcohol 2nd- decarboxy= CO2 of beta (c3) |
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a-ketoglutarate to succinyl-CoA |
2nd oxidative decarboxylation enzyme of a-ketoglutarate dehydrogenase- like pyruvate- 5 coenzymes TPP,CoASH, lipoic, NAD, FAD |
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substrate level phosphorylation |
succinyl-CoA- high energy hydrolysis drive P of GDP= GTP has phosphohistidine make succinate!! |
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succinate to oxaloacetate |
3 rxn 1-oxidation of single bond to double 2-hydration across double bond 3- oxidation of alcohol to ketone |
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succinate dehydrogenase |
FAD- dependent hydride removal!!! and deprotonation e' of succinate to FAD to UQ succinate to fumarate FAD is covalently linked to histidine that is on Enzyme |
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fumarate to L-malate |
trans-hydration carbonium or carbanion |
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malate dehydrogenase- completes |
NAD dependent +large G but in cell 0 bc oxaloacetate is LOW pulled forward by citrate synthase |
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steric preferences |
dehydrogenases that have nictoinamide Coenzymes- stereospecific transfer hydride pro-R or pro-S BC- enzymes are ASYMMETRIC STRUCTURES coenzymes fit into active site in one way L-malate- H goes to towards us and pro-R on nadh G3P- H to pro-S ethanol- H to pro-R of NADH
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energy consequences |
one acetate two CO2 one ATP 4 reduced coenzymes (3 NADH, 1 FADH) -40 kj/mol go and look at 625-626
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combo of glycolysis and TCA |
12 reduced coenzymes go to 34 ATP |
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carbon atoms of acetyl-coA |
carbonyl C of acetyl-CoA only CO2 in 1.5 turns methyl C of acetyl-CoA- never get rid, half in 2 cycles bc succinate is symmetric |
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fate of carbonyl |
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fate of methyl |
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TCA intermediates |
do biosynthesis a-ketoglutarate to glutamate to purine nucleo and Arg and Pro succinyl-CoA- porphyrins fumarate and oxaloacetate to aa and pyrimidine mitochondrial citrate to cytoplasm resource of acetyl-CoA and oxaloacetate |
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alanine to a-keto to |
pyruvate glutamate by adding amino acid |
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Anaplerotic- filling up rxn |
(1)pyruvate carboxylase- pyurvate to oxaloacetate- MOST IMPORTANT (2)PEP carboxylase- PEP to oxaloacetate- poor PEP carboxykinase- could be but wrong way CO2 weak to PEP carboxykinase oxaloacetate tight- spontaneous in opposite (3)- malic enzyme |
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anaplerosis |
insulin secretion! release insulin with increase in glucose OLD- ATP activated K channels of b-cells in pancrease NEW- anaplerotic enzymes feed alternative pathways to make cytosolic signals exercise increases ACTIVITY |
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more about b-cells |
B-cells- high pyruvate carboxylase, half of pyruvate goes to oxaloacetate to be malate to be in pyruvate/malate cycle malate to cytosol- make NADPH then pyruvate then go back around |
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reductive TCA cycle |
backwards- assimilate CO2 maybe 1st metabolic pathway energy from FeS with H2S to make FeS2= iron pyrite |
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TCA regulations |
citrate synthase- ATP, NADH, succinyl-COa inhibit isocitrate dehydrogenase- ATP inhibit, ADP and NAD+ activate a-ketoglutarate dehydrogenase- NADH and succinyl-coa inhibit, AMP activates pyruvate dehydrogenase- ATP, NADH, Acetyl-Coa inhibit, NAD+, CoA activate |
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pyruvate dehydrogenase |
regulated by phosphorylation if P'ed= inactive |
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Glyoxylate cycle |
only use acetate not possible with TCA only in plants net synthesis put in glycoxylate btw isocitrate and malate malata synthase- CLAISEN condensation of acetyl-coA and aldehyde of gyloxylate HELP PLANTS GROW IN DARK acetate= fatty acids |
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isocitrate lyase of glyoxylate cycle |
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glyoxysomes |
borrow 3 rxn from mitochondria to convert succinate to oxaloacetate succinate to fumarate to malate to oxaloacetate oxalo with glutamate from glyoxysome to make a-keto glutarate and Asp that both go to glyoxysome
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what does coenzyme A do |
activation of acyl group for trasnfer by nucleophilic attack activation of a-hydrogen of acyl group for extraction as a proton |
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mitochondrial disease |
affect mitochondrial enzymes defects in TCA mitochondria carry own DNA disease map to nuclear genome bc mitochondrial proteins are imported from cytosol hurt complex I- NADH- CoQ reductase more in men |
