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14 Cards in this Set

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TCA cycle
-occurs under aerobic condtions
-pyruvate from glycolysis is taken to mito & oxidized which forms co2,H2O,NADH & 15 ATP/pyruvate
-when E charge is dec in cell,pyruvate is oxidized
-once in mito pyruvate encounters 2 enzymes:pyruvate carboxylase & PDH
-byproducts are 2CO2,1GTP,3NADH,1 FADH
Pyruvate carboxylase
-pyruvate enters cell & CoA is acetylated
-this activates pyruvate carboxylase
-which directs pyruvate to gluconeogenesis
-defeciencies lead to lactic acid build up & CNS damage
PDH
-dec E in cell inhibits pyruv carbox
-pyruvate is metabolized via PDH
PDH complex
made of 3 enzymes:
-thiamine PP (pyrophosphate)
-lipoate (dihydrolipoyl transacetylase)
-riboflavin aka FAD(dihydrolipoyl dehydrogenase)
deficiencies:
-thiamine leads to wernicke-korsakoff inc pyruvate levels,alanine,& lactate
-lipoate is inhibited w/ binding of arsinate
Regulation of PDH
-negative regulators:NADH,Acetyl CoA
-positive regulators:
pyruvate,NAD,AMP,CoA
Rxn 1 TCA cycle: Citrate synthase
-conensation of methyl C of acetyl CoA w/ keto C of OAA
-has lots of free E
-very imp. in keeping cycle going in forward direction
-Regulation:
inhibited by ATP & citrate
Rxn 2:Aconitase
citrate--[aconitase]=>isocitrate
-isomerization of citrate to isocitrate,OH from central C of citrate
-stereospecific nature determines if the CO2 lost as isocitrate is oxidized t succinyl CoA
-regulation:inhibited by
fluoroacetate
Rxn 3: Isocitrate dehydrogenase
isocitrate--[Isocitrate dehydrogenase]=>alpha ketogluterate & NADH & CO2
-1st RATE LIMITING STEP
& 1st YIELD OF NADH IN TCA
-regulation:
activated by NAD+ & ADP
inhibited by NADH
Rxn 4:alpha ketogluterate dehydrogenase
isocitrate--[alpha ketogluterate dehydrogenase]=>succinyl CoA & CO2& NADH
-succ CoA & alpha keto are imp. in a.a synth
-high free E change
-regulation:
inhibited by NADH/ATP/succ CoA
Rxn 5: Succinyl CoA synthetase
succ CoA--[CoA synthetase]=>succinate,GTP,&CoA-SH
-reversible
-used in heme production
Rxn 6:Succinate dehydrogenase
succinate--[Succinate dehydrogenase]=>fumarate & FADH2
-reversible
-membrane bound enzyme
-FADH2 goes on to be oxidized by COq 10 in ox phos
Rxn 7:Fumarase
fumarate + H2O --[fumarase]=>malate -reversble
Rxn 8:Malate dehydrogenase
malate(can be xported through cytoplasm to initiate gluconeogenesis)
+ NAD --[malate dehydrogenase]=> oxaloacetate & NADH & H+
-reverisble
-synth Asp & pyrimidines
Regulation of TCA
Availability of Acetyl CoA regulated by PDH:
Inhibition- NADH,NAD+ &Acetyl CoA
Stimulation- CoA & AMP
-ATP & citrate inhibit citrate synthase
Isocitrate DH:
-Inhib:NADH,NAD+
-Stim:ADP
Ketogluterate DH:
-Inhib:NADH,ATP,succinyl-CoA