oxidative phosphorylation Flashcards
oxidative phosphorylation
the process in which ATP is formed due to the transfer of electrons from NADH and FADH2 to oxygen by a series of electron carries
where does oxidative phosphorylation occur
on the membrane of the mitochondria
generates… out of 30 of ATP in aerobic organism
26/30
how does oxidative phosphorylation work
carbo rules are oxidised in the TCA cycle to yield electrons with high transfer potential
the elective motive force is converted to the
proton motive force
the proton motive force is converted to
phosphoric transfer potential
this conversion of the elective motive force into the proton motive force is carried out by 3 proton pumps
1) NADH Q oxidoreductase 2) Q-cytochrome c oxidoreductase 3) cytochrome c oxidase
redox centres in proton pumps
Q Flans Copper ions
final phase of OP is carried out by
ATP synthase- an enzyme that is driven by the flow of protons back into the mitochondrial matrix
summary of oxidative phos
process in which ATP is formed as a result of the transfer of electrons from NADH or FADH2 to oxygen by a series of electron carriers. -four enzymes ar used to make up the ETC–> 3/4 of the proteins are linked to proton pumping
proton gradient is linked to
ATP production via ATP synthase
how many enzymes make up the ETC
4
ATP synthase
-ATP readily forms in the absence of the proton motive force but ATP does not leave the catalytic site unless prions flow through the enzyme -the role of the proton gradient is not to form ATP but to release it from ATP
do protons form ATP
no, they simply allow it to be released from ATP synthase
role of the proton motive force
not to form ATP but to release it from the ATP synthase
role of the proton motive force
not to form ATP but to release it from the ATP synthase
NADH-Q oxidorecutase (electron carriers in the respiratory chain)
structure- membrane spanning mem. and a long arm that extends into the matrix.
- NADH is oxidised on the arm!!
- electrons are transferred to reduce Q in the membrane
- 34-43 polypeptide chains
- contains prostheticc groups: clusters and FMN in the arm
reaction that occurs at NADH-Q oxidoreductase
pic
function of NADH-Q oxidoreductase
-transfer two high potential electrons from NADH to FMN (within the arm) -electrons from FMNH2 are transferred to a series of Fe-S clusters -electrons from Fe-S clusters are shuttled to Coenzyme Q
succinate dehydrogenae
-part of TCA cycle -integral mem protein in inner membrane -electrons from FADH2 are transferred to Fe-S clusters and then to Q -does not pump protons -less ATP formed by oxidation of FADH2 than NADH
less ATP formed by oxidation of..
FADH2 than NADH
Q cytochrome c oxidoreductase
-homo-dimer with 11 distinct polypeptides -major prosthetic groups are 3 hemes and an unusual (2Fe-2S) cluster function: catalyse transfer of electrons from QH2 to oxidised cytochrome c. Also pumps protons out of the mitochondrial matrix
cytochrome c oxidase
-13 polypeptide chain enzyme -major prosthetic groups include :CuA/CuA, Heme a, Heme a3-CuB
cytochrome c oxidase
-13 polypeptide chain enzyme -major prosthetic groups include :CuA/CuA, Heme a, Heme a3-CuB -Heme a3-Cu3 is the site of the reduction of oxygen to water
mechanisms of cytochrome c oxidase
1) protons are taken up from the matrix side to reduce one molecule of O2 to 2 waters 2) 3 additional protons are transported out of the matrix and released on the cytosolic side during the reaction 3) pumped proton double the efficiency of the free energy storage in the form of a proton gradient for the final step in the ETC
structure of ATP synthase
catalytic unit- F1 proton-conduction unit-F0 subunit
F1 subunit
catalytic unit -5 types of polypeptide -a and b subunits make up the bulk of F1 -chains are arranged in an a3b3 structure -central stalk consists of two proteins
f0 subunit
proton conduction unit -is the hydrophobic segment that spans the inner mitochondrial membrane -F0 contains the proton channel of the complex -this channel consist of 10c subunit and an a subunit
inhibition of OP
-tight coupling of electrons transport and oxidative phosphorylation can be disrupted by DNP -this compound allows protons to flow back across the membrane without going through ATP synthase- no proton gradient–> not ATP released from membrane
DNP
-tight coupling of electrons transport and oxidative phosphorylation can be disrupted by DNP -this compound allows protons to flow back across the membrane without going through ATP synthase- no proton gradient–> not ATP released frm membrane
uncoupling proteins (UCP)
in hibernating animals the uncouple of oxidative phosphorylation is one way of generating heat without the synthesis is ATP
