18.3 part 2
What are the prosthetic groups, matrix side, and membrane core of C1?
FMN, Fe-S
NADH
Q
What happens to the e- donated by NADH and FADH2?
They are passed to e- carriers in protein complexes
What are iron-sulfur proteins, what do they do and how do they cycle?
nonheme iron proteins
prominant e- carriers
cycle between Fe2+ and Fe3+ as they donate and accept e-
Where is succinate dehydrogenase of the CAC found?
Complex 2
What are the steps and characteristics of the Q-cycle?
1st half: 1 e- of QH2 reduces cytochrome c and yields Q.-
2nd half: another e- reduces cytochrome c and Q.-
4 protons pumped in 1 cycle
deficiency --> pathological condition
What are the prosthetic groups, matrix side and membrane core of C2?
FAD, Fe-S
Succinate
Q
What are the characteristics of coenzyme Q?
Derived from isoprene
Bind + and e-
exist in many oxidation states
What is Frataxin, what can a deficiency lead to and what does it impact?
A small mitochondrial protein that is necessary for Fe-S synthesis
deficiency leads to Friedrich's ataxia
causes issue in NS, cardio, skeletal
What is the function of FADH2 from the CAC?
reduce Q --> QH2, which then enter Q pool
What does cytochrome C oxidase do and what are the characteristics?
reduces oxygen to water
donates 4 e- from 4 molecules for reduction
during the rxn 8 protons are removed from the matrix, 4 are chemical protons used to reduce oxygen and 4 are pumped into the intermembrane space
What are the prosthetic groups, intermembrane side, and membrane core of C3?
Heme BH, BL, C, Fe-s
Cytochrome C
Q
What is present in the Q pool and where is the Q pool located?
oxidized and reduced Q
inner mitochondrial membrane
How are e- from NADH passed and where do they end up?
Q --> QH2 by complex 1
QH2 goes to Q pool
What is the function of e- from QH2 and where does it function?
reduces 2 molecule of cytochrome C at complex 3
What are the subunits of cytochrome C oxidase and how do they flow?
2 heme (a, a3)
2 copper (CuA - 2 copper ions, CuB - 3 histine residues, 1 is covalently bonded to tyrosine)
2 e- flow from cytochrome c --> CuA/CuA --> heme a --> a3 --> CuB
Heme a, a3, CuA, CuB
Cytochrome C
What is cytochrome C and what does it do?
An e- carrier that employs an iron incorporated into a heme
carries e- from C3 --> C4
What are the e- carriers between NADH and Q and what happens at this complex?
FMN and iron proteins
4 protons are pumped out of the matrix by complex 1
What are the cytochromes at complex 3
Cytochrome B and C1
What happens when the Fe of heme a3 and CuB are reduced?
They bind to oxygen and a peroxide bridge forms between them
How does heme iron cycle?
Between Fe2+ and Fe3+ as it donates and accepts e-
What is the function of ubiquinol?
The entry point for e- from FADH2 of flavoproteins
What does the Q cycle do?
funnels e- from 2 e- carrier to 1 e- carrier and pumps proteins
QH2 --> 2 e- carrier
Cytochrome C --> 1 e- carrier
What is the mechanism of cytochrome C oxidase?
1. Fe of heme a3 and CuB are reduced by 2 molecules of cytochrome c
2. heme a3 and CuB bind to O2 forming peroxide bridge
3. 2 e- and 2 protons come in and cleave bridge
4. 2 more protons come in and release water