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Biochem Muscle Weakness ATP 2


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electron flow in ETC is driven by?
redox potential, from most negative to most positive
where are protons pumped in the ETC? (what complex's)
What is the relationship between reduction potential and the ratio of oxidized to reduced forms of the substance?
more OXIDIZED means HIGHER Reduction Potential

If E'o is positive it means the substance has a higher affinity for electrons(than hydrogen electrode)
what is the relationship between delta E and delta G (equation)
DIRECT relationship

delta G = -nF delta E

n = electrons
F = eV
what is the relationship between the reduction potentials of a system and the concentration of the oxidized and reduced forms?
E = E'o + [RT/nF] [ln(ox/red)]

higher oxidation form means more positive potential energy
what are the electron carriers in a broader sense of the ETC

specifically flavins, iron sulfur centers and hemes
what is barth syndrome?
defect in cardiolipin, since cytochrome C is tethered to inner mitochondrial membrane by cardiolipin, a defect would lead to ETC dysfunction
how many electrons does the ETC carry?
2 e
the reduction of O2 to water often causes what to form, how do you prevent it?
causes ROS to form, need 4 electrons to prevent formation
nicotinamide nucleotides are weakly bound to enz's and are therefore?
coenz prosthetic group
coenz cosubstrate
coenz cofactor
coenz cosubstrate

most nicotinamide nucleotides are free and in equil with their enzyme substrates
oxidants or reductants strong or weak
weak oxidants
always accept two e and a proton
NADP is in the ox or reduced state primarily(in cells)
reduced state NADPH, because it functions more in anabolism

NAD is 90% oxidized state
functions more in catabolism
flavin nucleotides are
coenz prosthetic
coenz co substrate
coenz cofactor
prosthetic groups
NADH-UBQ oxidoreductase
takes two e from nadh into the FMN group, single electrons are then transfered to FeS centers and eventually to UBQ
Succinate dehydrogenase

takes electrons from Succinate via FAD and transfers along FeS centers
what complex's transfer electrons to ubiquinone?
complex I and II

glycerol 3 phosphate dehydrogenase

ETF(e transport flavoprotein)-UBQ oxidorecutase) . . .from fatty acid cycle
which complex's have heme groups?
IV III and cytochrome C
why does hemoglobin bind O2 and cytochromes do not?
b/c cytochromes have amina acid side chains at some of their coordination sites, thats why they do e transfer (ox/red) instead
what is the exception to the O2 vs ox/red situation?
cytochrome A binds O2 AND is oxidized as a result, last cytochrome of chain
characteristic features of heme
and what structures they are found in
cytochrome C oxidase complex IV, a and a3
has a long isoprenoid chain
attaches to apoprotein thru aa coordination bond

hemoglobin myoglobin, complex III

Cytochrome C
side chains cys cov bond to protein through thioether linkage, structure is conserved, side chains met and his coordination bondsz to apoprotein
describe the heme in cytochrome a3
coordination bonds to his and copper "B"
describe the redox centers in complex III
prosthetic groups

cyt c1, cyt b, reisk fe-s

each monomer of the 11 subunit complex is pear shaped with protuberances into mito matrix and reisk/c1 protruding into intermem space
the Q cycle
general description
happens in complex III, UBQ-Cytochrome C oxidoreductase
reduced Q transfers e to two cytochrom C molecules, uses heme prosthetic groups as e carriers
The Q cycle in depth
ubiquinol transfers an e to reisk which undergoes conformational change and transfers it to cyt c1
transfers an e to bL and then to bH

OVERALL 4 protons pumped into intermembrane space and 2 e transferred to the single e carrier cyt C1
complex IV where are the three essential subunits encoded?
mitochondrial DNA
remaining 10 are in nuclear DNA
subunit 1
12 transmem helices
subunit II
binds cyt c, large domain protruding into cytosolic face of inner membrane
complex IV how does it work
cyt c transfers e to Cu.A
Cu.A transfers to heme a
heme a transfers to binuclear center (heme a3-Cu.B)

binuclear center transfers to O2 using two H from matrix to make water (this helps with the proton grad)

overall 4 protons pumped into intermem space,
overall how many protons go to the cytosol for every 4 pumped taken up from the matrix
what is a negative effect of repurfusion of oxygen to ischemic areas after a myocardial infarction?
formation of ROS reactive oxygen species
how do you make superoxide
hydrogen peroxide
hydroxyl radical
superoxide, add an e to O2
H2O2, add 2 H and e to superoxide
OH, add a e and H to H2O2, makes water and OH radical
how does the cell defend against ROS
superoxide dismutase and catalase
what do superoxide dismutase and catalase do biochemically
superoxide: converts 2 superoxides to H2O2 and oxygen

catalase: converts 2 H2O2 to water and oxygen

NOTE: hydroxyl radical can from from H2O2 by addition of an e and H, This radical is converted to water by adding another e and H
what types of groups do iron sulfide compounds come in?
2,3,4 or 8 irons in the same protein

8 irons carry 2 e, everything else carries 1
what is the defining property of ubiquinone in chemical structure
long hydrophobic side chain that allows it to be free in the lipid core of the mem
what are the two broad categories of flavin nucleotides

dehydrogenases are the ones in the ETC, must be RE-OXIDIZED
heme a
binds oxygen and is oxidized as a result
heme c
cov bond through cys

coordination sites taken up by his and met (why it can't bind Oxygen)

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