Respiratory Chain (6) Flashcards
What is the only non-soluble enzyme of the CAC?
succinate dehydrogenase
What are the only steps that have enough exothermic energy to move H+ against the gradient, and out of the mitochondria?
steps 1, 3, 4 (complexes 1,3,4)
What are the five classes of oxidation/reduction centers in the respiratory chain?
- Flavo proteins
- FeS
- Q
- Cytochromes
- Cu
What are flavins and what is required for their synthesis?
two electron donor or acceptor (or 2H+)
1,4 addition
vitamin B2
What are the two forms of flavins?
FMN and FAD (bigger)
What two enzymes use flavins as a cofactor or prosthetic group?
NADH dehydrogenase - tightly bound FMN
Succ. Dehydrogenase - covalently bound FAD
What are the two iron-sulfur centers in the respiratory chain that accept electrons from flavins and Q? How many electrons do they accept?
one electron donor or acceptors:
- Fe2S2 of complex III
- Fe4S4 of succinate dehydrogenase
If an iron center is acidified, what occurs?
H2S gas is released
Where does Q reside?
in the lipid bilayer - very hydrophobic
How many electrons does Q accept/donate and by what method?
2 electrons
1,6 addition
What does Q function as?
an electron buffer
10 fold excess over other components
Is Q a cofactor or prosthetic group?
cofactor
How many electrons does heme accept/donate?
one electron
What two amino acids does the iron atom of the heme group in cytochrome C, coordinate with? what else does it coordinate with
methionine and histidine and the 4 porphyrin ring nitrogens
What is the heme covalently attached to in cytochromes C and c1?
two cysteine side chains
Cytochrome b:
- where is it found
- how many hemes does it have
- what is it’s structure
- complex III
- two hemes
- two transmembrane segments
How many electrons does a copper center donate/accept?
one electron
How many coppers does copper center A contain?
two coppers
What forms the O2 binding site at the end of the respiratory chain?
copper center B and heme iron of Cyt a3
What components make up cytochrome oxidase or complex IV?
- cuA
- Cytochrome a
- cytochrome a3
- Cu B
Why is the participation of two copper centers and two heme irons in cytochrome oxidase important?
to rapidly deliver 4 e- to O2
avoid production of H202 and superoxides
Is the stabilization of an electron exothermic or endothermic?
exothermic
-coupled to the endothermic generation of an electrochemical gradient
Put these components of the respiratory chain in order of increasing affinity from least to most:
Q, b, a, c, NAD
- NAD
- Q
- b
- c
- a
How many catalytic sites for ATP synthesis does F1 contain?
3 sites
Which part of ATP synthase is hydrophobic?
Fo
What is respiratory control?
an electrochemical gradient functions as a common intermediate linking oxidation to phosphorylation
rate of respiration controlled by availability of ADP
-protons need to be carried back into matrix in order for the gradient to proceed
What is the formula for P/O ratio?
ADP Consumed/ O2 consumed
=ATP formed per pair e- from substrate to O2
Will ATP be produced if NADH is added to mitochondria?
no - there is not a transporter
Where is the respiratory chain located?
inner mitochondrial membrane
What is the function of the respiratory chain?
breaks up 52 kcal/mol
available from the flow of 2 e- from NADH to O2
-into 3 equal amounts
