Oxidative Phosphorylation/ Electron Transport Chain

Oxidative phosphorylation

also know as the electron transport chain. takes place in the inner mitochondrial membrane

Electron donor

NADH and FADH2, these to olceules stor energy in the proton graient

ATP synthesis

This enzyme uses the protons in NADH and FADH2 to generate ATP

Electron acceptor

Oxygen

FMN

acts like FAD+

Iron-Sulfur proteins

example of these proteins are in a variety of metalloproteins, such as the ferredoxins, as well as NADH dehydrogenase, hydrogenases, coenzyme Q - cytochrome c reductase, succinate - coenzyme Q reductase and nitrogenase.[1] Iron-sulfur clusters are best known for their role in the oxidation-reduction reactions of mitochondrial electron transport.

cytochrome b, c1

cytochrome b has heme b.

Coenzyme Q - cytochrome c reductase ("Complex III")

cytochrome a, a3

this cytochrome has heme A.

its also called Cytochrome c oxidase
("Complex IV") with electrons delivered to complex by soluble cytochrome c (hence the name)

Whats the complex order in oxisative phosphorylation pathway?

complex 1 to 3 to 4 or complex 2 to 3 to 4

NADH CoQ reductase

Complex I in ETC, reduces coQ oxidizes NADH, transports 4H+ to inner mitochondrial space, 44 components, L shape, bound FMN + 7 Fe-S centers primarily in matrix domain

Succinate CoQ Reductase

Complex II in ETC, reduces coQ and oxidized FADH2, no proton transfer, connects TCA to ETC. Contains bound FAD, 3 Fe-S clusters + a heme
Is the only enzyme of the 4 complexes of oxidative phosphorylation to not pump protons into the mitochondrial inner membrane space.
is in the Citric Acid Cycle and in oxidative phosphorylation.

CoQ Cytochrome c Reductase

Cytochrome c is a component of the electron transport chain in mitochondria. The heme group of cytochrome c accepts electrons from the bc1complex and transfers electrons to the complex IV. Cytochrome c is also involved in initiation of apoptosis.
Soluble mobile Electron carrier

Complex III in ETC

Cytochrome C Oxidase

Complex IV in ETC, oxidizes coQ, reduces oxygen to water, 2 H+ to intermembrane space (but 4 H+ transfer), cyanide is deadly because it inactivates cytochrome c oxidase.

Standard Reduction Potential

E= E0' + RT/ (nF) ln (ox)/(red)
n= numer of electrons transferred (equvilent/mol)
F= 96.5 kJ/V mol or 24.06 kcal/V m (Faraday)

Out of the 14 polypeptides encoded in Mitochondrial DNA, which are a part of the Electron Transport Chain?

13

ADP translocase

is an integral membrane protein

Uniporter

s an integral membrane protein that is involved in facilitated diffusion

Synporter

Transports both ADP and ATP into the mitochondria

Antiporter

Transpoerts ADP into the mitochondria and ATP out

Outer mitochondrial Membrane

permeable to compounds with molecular weights < 10,000

Inner Mitochondrial Space

H+ pumped here via the action of the electron transport chain

is the positively charged side which become more acidic

Inner Mitochondrial Membrane

impermeable to most compounds, Including H+; home of electron transport chain and ATP synthase

Matrix

site of NADH production via citric acid cycle and where H+ is removed.

this is also a negitively charged space which becomes more basic

pH of the mitochondrial matrix

7.9-8.0, H+ pumps out of it so pH raises

pH of cytoplasm

7.4

pH inside the golgi

6.6

pH inside the lysosome

4.5-5.0

Co-enzyme Q (notecard)

is a mobile electron in the INNER MITOCHONDRIAL MEMBRANE made in (n=10)

Cytochrome c (notecard)

is a moble electron carrier in the INNER MITOCHONDRIAL SPACE made in cytoplasm

Inner membrane space

is the positively charged side which become more acidic

Matrix

is the negitively charge side which become more basic

Q cycle

This happen in complex III, it explains the movement of protons

summarize, the first reaction of Q cycle is:

CoQH2 + cytochrome c1 (Fe3+) → CoQ−• + cytochrome c1 (Fe2+) + 2 H+ (intermembrane)
Then the second reaction of the cycle involves the reduction of the transient semiquinone by another electron to give CoQH2:

CoQH2 + CoQ−• + cytochrome c1 (Fe3+) + 2 H+ (matrix) → CoQ + CoQH2 + cytochrome c1 (Fe2+) + 2 H+ (intermembrane)
Combining the two equations, we have the overall reaction of Q cycle:

CoQH2 + 2 cytochrome c1 (Fe3+) + 2 H+ (matrix) → CoQ + 2 cytochrome c1 (Fe2+) + 4 H+ (intermembrane)

Approximately how many protons are transported to the intermembrae space per NADH oxidized

10 H+

ATP synthase

Makes ATP from proton gradient,F0 is the integral membrane subunit a1b2c10

ATP synthase - F1

complex attached to F0 and faces the matrix.

-consists of a3B3Se
-Y-c complex rotate together relative to the (ab)3 complex and cause the confrontational changes in B that drive ATP synthesis

F0

integral membrane protein complex
-a1b2c10

subunit a

holds proton and transfers them to subunit C as it rotates around

c (10)

the c subunit has carboxylated side chains of a highly conserved Asp and Glu residue on each subunit that serves as a proton bonding site.

a3 and B3

in F1 of ATP synthesis there are 3 total ab complexs that make 3 different form L-T-O

ySe

S and E subunit of F1 are small and Y is composted of two long alpha helices the Y interacte with the ab complex for as it rotate t=so does the ab complex.

whats the number of ATP formed per 2e- tranfered, in eukaryotes?

when converting NADH to ATP you generate 2.5 ATP

when converting FADH2 to ATP you generate 1.5 ATP

What is the number of ATP formed per 2e- transfer in prokaryotes?

When converting NADH to ATP you get 3 ATP
when converting FADH2 to ATP you get 2 ATP

How Does NADH get into Mitochondria?

through either the glycerol Phopshate shuttle or the Malate-Aspartate Shuttle

Oxaloaceate

this molecule is not an intermediate of the citric acid cycle

The Net ATP yield per glucose?

32