Oxidative Phosphorylation

Malate- Aspartate Shuttle is apart of

Aerobic Metabolism

Reasoning for Malate-Aspartate Shuttle

NADH from glycolysis in the cytosol needs to get to the matrix for Oxidative Phosphorylation. However, NADH cannot move across the inner mitochondrial membrane and instead must use a shuttle system.

NADH used in the Malate-Aspartate Shuttle comes from

Glycolysis

NADH from glycolysis is recycled by ___

Cytosolic Malate DH

Malate-Aspartate Shuttle Linkage

uses malate, OAA, and Asp (which are present in both the cytosol and the membrane)

OAA + NADH ⇌ Malate + NAD⁺ (Malate DH)

OAA + NH₃ ⇌ Aspartate

OAA cannot go through the matrix membrane, but aspartate can

Malate is used as a __ by the Malate-Aspartate Shuttle

H⁺ carrier

The Malate-Aspartate Shuttle recycles

Glycolysis NADH

Chemiosmotic Theory

1. An H⁺ gradient drives ATP Synthesis

2. The H⁺ gradient is made by an oxidative process that reduces O₂ to H₂O

The Oxidative in Oxidative Phosphorylation refers to

Electron Transport Chain (ETC)

removes 2e⁻ from NADH, FADH₂, and adds them to O₂

makes a H⁺ gradient that drives ATP Synthesis 

__ drives ATP Synthesis

H⁺ gradient

The Oxidative in Oxidative Phosphorylation includes the following equations

The Phosphorylation in Oxidative Phosphorylation includes the following equations

Oxidative Phosphorylation Formulas

The ____ part of Oxidative Phosphorylation makes an H⁺ gradient

Oxidative

The ___ part of Oxidative Phosphorylation uses an H⁺ gradient

Phosphorylation

The Phosphorylation part of Oxidative Phosphorylation

ATP Synthesis 

uses H⁺ gradient to make ATP

produces most of ATP made in aerobic cells

Mitochondria

Electron Transport Chain

ATP Synthase (Ox Phos)

Mitochondria Inner Membrane Space

H⁺ gradient (Ox Phos)

Matrix

TCA

FA Oxidation

AA Oxidation

Electron Transport Chain (ETC)

moves electrons to O₂ and creates a H⁺ gradient

Succinate DH is __

complex 2

Electron Carriers include

NADH, FADH₂/FMDH₂, QH₂, Fe⁺², 2Cu⁺¹

NADH as Electron Carrier

carries 2 electrons

soluble in water 

NADH → 2e⁻ + NAD⁺ + H⁺

FADH₂/FMDH₂ as an Electron Carrier

carries 2 electrons

always in a protein

FADH₂ → FADH• + 1e⁻ + 1H⁺ → FAD + 2e⁻ + 2H⁺

QH₂ as an Electron Carrier

carries 2 electrons

soluble in the membrane

QH₂ → QH• + 1e⁻ + 1H⁺ → Q + 2e⁻ + 2H⁺

Fe⁺² as an Electron Carrier

carries 1 electron as part of a heme of a F-S complex in protein

Fe⁺² → Fe⁺³ + e⁻

Cu⁺¹ as an Electron Carrier

carries 1 electron

in protein

2Cu⁺¹ → 2Cu⁺¹.5 + e⁻

Electrons are always carried __ during ETC

one at a time to O₂

Coenzyme Q (ubiquinore)

Hydrophobic

Soluble in membrane

Carries 2 electrons

Loosely bound to proteins  

__ is loosely bound to proteins

Q

__ is tightly bound to proteins

Iron

ETC Complexes include

Complex 1, Complex 2: Succinate DH, Complex 3, Complex 4

Complex 2 includes what prosthetic group

FAD

Carriers within complexes

FMN, FAD (2e⁻)

Fe-S, Hemes, Cu (1 e⁻)

Carriers between complexes

QH₂: between 1 and 3, or between 2 and 3 (carries 2e⁻)

Cyt c: between 3 and 4 (carries 1 electron)

Either start at complex __ or __

1 or 2

If you start at complex 1, for every 1 NADH, you get __ H⁺ pumped

10

If you started at complex 2, for every succinate (FADH₂), you get __ H⁺ pumped

6

Complex 1 oxidizes

1 NADH 

Complex 1 reduces

1 Q

Complex 1 pumps

4 H⁺ into the P site

Complex 2: Succinate DH oxidizes

1 Succiante

Complex 2: Succinate DH reduces

1 Q

Complex 2: Succinate DH

does not pump H⁺

__ is the ultimate produce of Succinate DH

QH₂.

FADH₂ is just an electron carrier within the protein

__from __ also reduces Q to QH₂ with no H⁺ pumped

FADH₂ from β-oxidation

Complex 3 oxidizes 

1 QH₂

Complex 3 reduces 

2 Cyt c

Complex 3 pumps

4 H⁺ to the P side

Complex 4 oxidizes

2 Cyt c

Complex 4 reduces

½ O₂

Complex 4 pumps

2 H⁺ 

Complex 4 prevents

electron transfer

Prevent electron transfer in Fe⁺³ from with

HCN

Prevent electron transfer in Fe⁺² form with 

CO

ETC can lead to 

oxidative damage(damage to DNA/proteins)

Reduction Potential (∆E°’)

the affinity a compound has for electrons (stability with electrons)

+∆E°’ = ∆G°’ ==

exergonic = more stable with electrons

During ETC, the electrons always

move to the molecule that wants them more

All complexes are

exergonic

ATP Synthesis is catalyzed by

Complex V (ATP Synthesis)

ATP Synthesis is dependent on

1. Presence of an H⁺ gradient (made by ETC)

2. Inner membrane impermeability

3. H⁺ movement through ATP Synthase (to make ATP)

(Part of Chemiosmotic Theory)

Complex V is made up of

F_O , F₁, 𝛾

F_O

in membrane 

pumps H⁺

F₁

in matrix

synthesizes ATP

𝛾 

links the functions of F_O and F₁

Stator

helps to stabilize F_O and F₁

F_O pumps H⁺ from P to N side and turns

itself and 𝛾 counterclockwise

F₁ Synthesis of ATP

ADP + Pi → ADP + H₂O

Three identical sections (α/β) that are in three different conformations and move in a set order

The three conformations of (α/β) sections

1. Open (binds nothing) 

2. Loose (binds ADP, Pi)

3. Tight (binds ATP)

The open conformation binds

nothing

The loose conformation binds

ADP, Pi (substrates)

The tight conformation binds

ATP

𝛾 forces ___ conformation and turns ___

O, counterclockwise

L is ___ from O

clockwise

T is __ from O

counterclockwise

__ H⁺ is pumped for every conformation change

3

It takes energy to ___ ATP

release (not make)

Takes __ H⁺ pumped from P to N to make 1 ATP

4

To release ATP, it takes __ H⁺

3

To transport Pi into the matrix, it takes __ H⁺

1

P/O ratio is

the ATP yield from the reduction of ½ O₂

NADH to ½ O₂ gets __ H⁺

10

FADH₂ to ½ O₂ gets __ H⁺ pumped

6

NADH P/O Ratio

2.5 ATP

FADH₂ P/O Ratio

1.5 ATP

There is ___ regulation of Oxidative Phosphorylation

little

The overall rate of oxidative phosphorylation depends on 

substrate availability and 

cellular energy demand (no allosteric control)

Important Substrates for Oxidative Phosphorylation

NADH, Succinate (FADH₂) O₂, ADP and Pi

We need __ the substrates for oxidative phosphorylation to work

all

The ______ couples the electron transport chain to ATP Synthesis

proton gradient 

____ move H⁺ across the inner membrane

Uncouplers

Uncouplers uncouple oxidative phosphorylation by

destroying the proton gradient

In the presence of uncouplers, the body is 

breaking down compounds for energy, but little ATP is made (lots of heat instead)

Uncouplers move H⁺ across the membrane using

1. Proton Transporter (neutral)

2. Membrane soluble compound

CO inhibits

Complex IV of ETC

The rate-limiting step is

the release of ATP into the matrix (tight to open)

Water Molecules Released During ATP synthase

(# of total molecules of NADH and FADH₂) + (# of NADH x 2.5)+ (# of FADH₂ x 1.5)

NADH electrons Transport To Ox Phos

• First, they are transferred to OAA to make Malate (via cytosolic malate DH).

• Then, malate passes through the mitochondrial membrane to the matrix

• Once in the matrix, the electrons then pass from Malate to OAA to NAD⁺ to make a new NADH (uses mitochondrial malate DH).

• Then they can react with complex 1 in the ETC

Pathway for Electrons from NADH through electron transport

• go into complex 1 as Q to make QH₂ (4 protons are pumped to the P side)

• QH₂ goes into complex 3, where the two electrons are transferred to make two reduced Cyt c (4 protons are pumped)

• The two Cyt c go into Complex 4, and the two electrons are then transferred to ½ O₂ to make one H₂O (2 protons are pumped) 

• A total of 10 protons are pumped.