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Biochem Muscle Weakness ATP 3


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what drives substrate level phos?
high energy intermediate (between two reactions)

ex) alpha keto glut to succinyl CoA
succingly coa to succinate(makes GTP)
P:O ratio
high vs low
atp formed: oxygens used

nadh is about 3
succinate is about 2
chemiosmotic hypothesis
proton grad is primary means of energy transduction
mitchel 1961
describe ATP synthase subunits
a reverse proton pump

Fo - A B C - charged aa, wants proton in acidic (intermem space) doesnt want it in basic (matrix) causes motor to turn and protons to pump down [grad]

F1 - alpha, beta (catalytic site, ATP SYN) gamma (connects to Fo) delta, epsilon
describe l t and o states for beta of F1
l - attracts ADP and Pi
t - active, where ATP form is
o - open, release (little affinity for)atp
is inner mem permeable or non pemeable
very impermeable so need translocases (uaually antiport)
two types of transport systems
electrogenic - membrane potential ie Ca++ uniport, ATP leaves mito via electrogenic antiport with ADP

ligand - conformational change
Adenine nucleotide translocation
atp in adp out 1:1
+ charge outside from proton grad so - ATP will move out
phosphate translocase
P (H2PO4) and H both into matrix
NADH transport into mito
NADH shuttle mechanism

using malate dehydrogenase

oxaloacetate -> malate, this oxidizes NADH

malate goes inside cell via malate-aspartate shuttle

malate--> oxaloacetate reducing NAD+

SEE PAGE 415 for more detail??
Inhibitors and uncouplers of ox phos

inhibitors: two types and examples
respiratory inhibitors: act on respiratory chain
CN and CO inhibit cytochrome a3 of complex IV cytochrom oxidase

phosphorylation inhibitors:
act on enzymes of ATP syn
oligomycin blocks Fo of atp synthase
uncouplers of ox phos
2 ex
DNP 2,4-dinitrophenol, weak acid thats protonated in intermembrane space and then diffuses into matrix destroying the [grad]

UCPI (thermogenin) - brown adipose, membrane spanning protein allows influx of protons into mito

Note: uncouplers actually INCREASE oxygen consumption
ancillary reactions
energy coupled reactions
examples of mitochondrial ancillary reactions
Ca uptake
ATP/ADP exchange
aa aspartate to cytosol(-?)(possibly, because asp in C of atp synthase when protonated is neutral and thats what causes the turning)
Ca ancillary energy coupled reaction
activates PDH through phosphatase
moves into matrix, since its +charged it dissipates the gradient a little
What do high [] of ca do in mito?
lead to apop through pore formation and release of cytochrome C
ATP ADP transport
atp out ADP in, atp is -4, adp is -3 so net neg charge moving out, dissipates pH grad
negativly charged, moves out of matrix into cytosol
reduced by NADH, less NADH means less ETC
Ancillary rxns
dont req ATP, use e transport
competes with ATP synthesis

stimulates e transport

inhibited by respiratory inhibitors and uncouplers, not by phosphorylation inhibitors
the three mitochondrial diseases
Exercise intolerance
lebers hereditary optic neuropathy
complex I decreased activity
NADH-ubiquinone oxidoreductase
myoclonic epilepsy and ragged red fiber

complex IV cytochrome c oxidase mutation in tRNA
excersize intolerance
not maternal inheritance
cytochrome b mutations
somatic in muscle
what does released cytochrome c do in apoptosis
forms apoptosome with factors in cytosol, this activates caspase leading to cell destruction

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