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acetylCoA + OAA --> citrate
- citrate synthase enzyme
- nucleophilic attack on OAA
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- citrate --> isocitrate
- enzyme: acotinase, forces chirality
- dehydration followed by hydration rxn (intermediates left out)
- cant oxidize citrate its a 3o alcohol, isocitrate is a 2o alcohol that can be oxidized.
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- isocitrate --> a-ketoglutarate
- enzyme: isocitrate dehydrogenasefirst of 4 oxidation reactions
- creates first NADH of the cycle
- the last COO- from isocitrate (under the grp that came from AcetylCoA) leaves as CO2
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- a-kg --> succinylCoA
- enzyme: a-kg dehydrogenase: same as pyruvate dehydrogenase, does everything the same, TPP nucleophilic attack, LIP, CoA
- its the 2nd oxidation rxn (oxidative decarboxylation)
- TPP attacks 2nd Co of a-kg and the first COO- grp leaves as CO2
- makes FADH2 and NADH
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- 1st step in SuccinylCoA --> Succinate
- added a pi group to succinylCoA
- enzyme: succinate synthetasephosphorylation is NOT an oxidation rxn
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- Last intermediate step in succinylCoA --> Succinate
- pi grp removal makes GDP-->GTP
- enzyme: succinate synthetase
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- 1st step in Succinate --> OAA
- enzyme: succinate dehydrogenasemakes FAD --> FADH2
- so this is an oxidation
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- last step in Succinate --> OAA
- enzyme: succinate dehydrogenaseOH grp gets oxidized, making NAD+ --> NADH
- *remember* succinate dehydrogenase is complex II in the e- transport chain
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Ways to inhibit Pyruvate Dehydrogenase
- high [conc] of ATP, binds allosterically @ I so TPP cant attack pyruvate, easily reversilble
- high [NADH] / low [NAD+]: when NADH and ATP is high energy needs have been met
- phosphorylation by a kinase: high [conc] of ATP and NADH promote phosphorylation:
- adds a pi group to complex I - creates repulsion (p groups are negative) and changes shape of PDH
- covalent bond, not easily reversed. phosphatase must remove the p group
- ATP binds to Ca2+ / Mg2+ and prevents activation enzyme phosphatase from being activated
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Ways activate Pyruate Dehydrogenase
- low [ATP]: results in free Ca2+ / Mg2+ and low [ATP] means wont bind to inhibition site
- Phosphatase enzyme: removes pi grp, needs high [Ca / Mg]
- high [ADP] and [pyruvate] inhibit kinase, allows PDH to keep going
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inhibitors and activators for phosphofructo kinase
- ATP: inhibitor, allosteric
- AMP: activator, allosteric but larger K than ATP
- fructose 2,6-biphosphate is an allosteric activator
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Membranes: saturated
- all single bonds
- can twist around each other better
- higher melting temp
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membranes: unsaturated
- has a c=c double bond
- tails more rigid than saturated
- lower melting temps
remember: shorter chains also means lower melting temp
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delta G for uncharged species
- deltaG = RT ln [to] [from]
- remember deltaG is favorable (-) when you move from [high] to [low]
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deltaG for charges species
- deltaG = RT ln [to]/[from] - NFEo
- N = charge
- F = 96,500 J/V
- E = (+) or (-) .07V
depends on where ur going: (+) if ur going towards ur opposite charge, (-) if your going from to ur same charge (repulsion, yuck) - *remember* outside of membrane is (+), inside of membrane is (-)
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