electron transport chain 4 Flashcards
What is the name of complex 2?
Succinate dehydrogenase
What is ‘special’ about succinate dehydrogenase?
No protons are translated across the inner mitochondrial membrane
How is succinate dehydrogenase directly linked to the citric acid cycle?
Oxidises succinate to fumarate, which converts FADH2 into FAD
How are the electron pairs transferred through complex 2?
Series of Fe-S clusters and cytochrome b560
What does FAD stand for?
Flavin adenine dinucleotide
What is the name of complex 3?
Ubiquinone - cytochrome c Oxidoreductase
What are the two binding sites in complex 3?
Qp and QN
How are the electrons transferred through complex 3?
several prosthetic groups that function as electron carriers (Fe–S cluster and hemes bL, bH, and c1)
How does the oxidation of QH2 occur?
to produce Q and two molecules of reduced cytochrome c (Cytc) requires the Q cycle .
How many cytochrome C molecules are required after complex 3?
2 molecules needed
How are cyt c groups linked to haem groups?
Covalently linked to protein through thiol groups from cis residues
What are the 3 types of harm group in the ETC?
a, b and c
Why must Coq and CyC make two trips?
transport 1e- at a time, so must make two trips to transfer 2e- from NADH or FADH2 to ½ O2 to form H2O
What is the name of complex 4?
Cytochrome c Oxidase
How many Hydrogens are used in regards to the complex 4?
4
How many protons are translated through complex 4?
2
what are the use of the other 2 hydrogens in the complex 4?
used to form water
How many hydrogens are pmed through starting with CoQ and FADH2 molecules?
6
What do the F1 and Fo components involve in ATP synthase in bacteria and yeast?
F1 = catalytic activity Fo = H plus channel
What is the δ subunit in yeast homologous to in bacteria?
homologous to the bacterial ε subunit
What are the 3 parts of ATP synthase made up of?
- stator
- Rotor
- Headpiece
What is the strator subunit made up of?
- half-channels for H+ to enter and exit FO, plus stabilizing arm (b, d, h and OSCP)
What is the headpiece subunit made up of?
- : hexameric a3b3 unit responsible for ATP synthesis
What is the rotor subunit made up of?
c + g + d + e rotate as H+ enter and exit c-ring
What is the role of the rotor?
responsible for translating proton-motive force into protein conformational changes in the headpiece
How do protons pass through ATP synthase?
The protons, come through the a subunit. There are two channels , each channel gets the proton part way through a membrane
The protons get so far across in one a channel, and then they go on round the rotary part of c subunit and then reaches the other channel in the a subunit and gets across the membrane
Which part of ATP synthase is catalytic?
Beta subunit
What is the first basic principle for the binding mechanism of ATP synthesis?
Gamma directly contacts all three b subunits, but each interaction is distinct, giving rise to 3 different b conformations
What is the second basic principle for the binding mechanism of ATP synthase?
ATP binding affinities of the 3 b subunits are T, L and O (tight, loose and open)
T: ATP bound
L: ADP and Pi bound
O: ATP is released
What is the third basic principle for the binding mechanism of ATP synthase?
H+ flow through FO causes rotation of g subunit counterclockwise during ATP synthesis (looking at F1 from matrix side).
With each 120° rotation, b subunits switch conformation sequentially L T O L
Who were given the prize for the study of structure of ATP synthase
John E. Walker and Paul D. Boyer
What was the experimental evidence that proved how ATP synthase rotates?
Experimental proof that ATP synthase rotates, and that it rotates
in reverse under conditions that favour ATP hydrolysis rather than ATP synthesis
how was the experiment done to prove how ATP synthase rotates?
Took the catalytic part and attached the long filament to the gamma filament that fluoreses
Who came up with the ATP synthase experiment?
Yoshida and Kinosita
How does the experiment work in which theF1 component as a nanomotor driving ATP synthesis in absence of electrochemical proton gradient
. a.In place of the actin filament , a magnetic bead was attached to the γ subunit via streptavidin. b.Six electromagnets in a circular arrangement around the experimental chamber were used to force rotation of the magnetic bead to drive ATP synthesis in the absence of a proton gradient.
How does H+ movement cause rotation of gamma subunit?
Two channel model
How does H+ movement cause rotation of gamma subunit?
H+ neutralizes D59 allowing c subunit to rotate 36° into hydrophobic membrane
This rotation allows D59 in a different c subunit to access the second half-channel in the a subunit and exit the channel because of the low H+ concentration on matrix side
Carousel analogy: each H+ must ride once around the c ring carousel to exit into matrix
