Oxidative phosphorylation Animation - Formation of ATP & sites of ATP synthesis
Summary
TLDRThis script delves into oxidative phosphorylation, a vital cellular process for ATP production. It highlights three key ATP-synthesizing sites within the electron transport chain: between NAD and Coenzyme Q, Coenzyme Q and Cytochrome C, and Cytochrome C and Oxygen. The script explains the role of the F0F1 ATPase enzyme, commonly known as ATP synthase, in harnessing the proton gradient across the mitochondrial membrane to synthesize ATP. The mechanism of ATP synthesis is further elucidated through the binding change mechanism proposed by Paul Boyer, emphasizing the molecular motor function of the F1 complex and its gamma subunit's pivotal role in the process.
Takeaways
- π Oxidative phosphorylation is the process of ATP formation coupled with the transfer of electrons through the electron transport chain.
- π There are three main ATP synthesizing sites in the electron transport chain: between NADH and Coenzyme Q (Complex I), Coenzyme Q and Cytochrome C (Complex III), and Cytochrome C and Oxygen (Complex IV).
- β Complex II does not contribute to ATP synthesis, highlighting the specificity of ATP production sites within the electron transport chain.
- π‘ The energy released at Complex I and Complex III is utilized to synthesize one ATP molecule at each site through the movement of hydrogen ions.
- π Complex IV (Site III) is unique as it only synthesizes half an ATP molecule due to the pumping of two hydrogen ions into the intermembrane space.
- π’ The entry of one NADH molecule into the respiratory chain results in the production of 2.5 ATP molecules, while one FADH2 molecule yields 1.5 ATP molecules.
- π The chemiosmotic theory by Peter Mitchell (1961) explains the coupling of oxidation and phosphorylation through a proton gradient across the mitochondrial membrane.
- π§ ATP synthase, also known as Complex V, is a molecular motor embedded in the inner mitochondrial membrane, consisting of F0 and F1 subcomplexes.
- π The F0 subcomplex forms a proton channel and is responsible for the rotation that drives ATP synthesis, while the F1 subcomplex contains the catalytic site for ATP production.
- π The gamma subunit of the F1 complex rotates due to the proton flow through F0, causing conformational changes necessary for ATP synthesis in the beta subunits.
- π Respiratory control refers to the tight coupling of electron flow and ATP synthesis, ensuring oxygen consumption is dependent on the availability of ADP.
- π The binding change mechanism, proposed by Paul Boyer, describes the process of ATP production involving the re-entry of protons and the subsequent rotation and conformational changes in the F1 complex.
Q & A
What is oxidative phosphorylation?
-Oxidative phosphorylation is the process where ATP is formed during the transfer of electrons through the electron transport chain, coupled with the phosphorylation of ADP by an enzyme, utilizing the energy produced.
How many ATP synthesizing sites are there in the electron transport chain?
-There are three ATP synthesizing sites in the electron transport chain: between NAD and Coenzyme Q (Complex I), between Coenzyme Q and Cytochrome C (Complex III), and between Cytochrome C and Oxygen (Complex IV).
Why does Complex II not produce any ATP?
-Complex II does not pump protons into the intermembrane space, which is necessary for the generation of the electrochemical gradient that drives ATP synthesis.
How many ATP molecules are synthesized at Complex I and Complex III?
-At both Complex I and Complex III, one ATP molecule is synthesized per site due to the proton gradient created by the pumping of four hydrogen ions.
What is the role of Complex IV in ATP synthesis?
-Complex IV, also known as site three, is responsible for pumping two hydrogen ions into the intermembrane space, which results in the synthesis of only half an ATP molecule when they are pumped back into the mitochondrial matrix.
How many ATP molecules are produced when one NADH molecule enters the respiratory chain?
-When one NADH molecule enters the respiratory chain, it produces 2.5 molecules of ATP, considering the energy liberation and proton gradient across the complexes.
What is the significance of the Kimmi osmotic theory in oxidative phosphorylation?
-The Kimmi osmotic theory, proposed by Peter Mitchell, explains the coupling between the oxidation of reducing equivalents and the phosphorylation of ADP into ATP through a proton gradient across the mitochondrial membrane.
What are the two sub-complexes of ATP synthase?
-The two sub-complexes of ATP synthase are Fo (also known as F naught), which is hydrophobic and forms a proton channel, and F1 (also known as F subunit), which is hydrophilic and contains the catalytic site for ATP synthesis.
How does the rotation of the Fo complex and the gamma subunit of F1 complex contribute to ATP synthesis?
-The flow of protons through Fo causes the rotation of the Fo complex along with the gamma subunit of F1, which in turn causes conformational changes in the beta subunits of F1, leading to ATP synthesis.
What is the respiratory control, and how does it relate to ADP availability?
-Respiratory control is the tight coupling of electron flow and ATP synthesis in mitochondria, ensuring that oxygen consumption depends on the availability of ADP. It adjusts electron flow and oxygen consumption based on the body's energy demands.
What is the binding change mechanism, and how does it explain ATP production in the F1 sub complex?
-The binding change mechanism, proposed by Paul Boyer, states that the re-entry of protons through the Fo sub complex causes rotation of the gamma subunit of F1, leading to conformational changes in the beta subunits, which is the site of ATP synthesis.
Outlines
π Oxidative Phosphorylation and ATP Synthesis Mechanism
The first paragraph delves into the biochemical process of oxidative phosphorylation, a critical component of cellular respiration. It explains how ATP is synthesized at three key sites within the electron transport chain: between NAD and Coenzyme Q (Complex I), Coenzyme Q and Cytochrome C (Complex III), and Cytochrome C and Oxygen (Complex IV). The paragraph clarifies that ATP is not produced at Complex II, and details the role of the enzyme F0F1 ATPase in the phosphorylation of ADP to ATP. It further discusses the energy released at these sites, emphasizing that the proton gradient created by the pumping of hydrogen ions is essential for ATP production. The paragraph also corrects previous assumptions about the ATP yield from NADH and FADH2, providing updated values of 2.5 and 1.5 ATP molecules respectively. Finally, it introduces the chemiosmotic theory proposed by Peter Mitchell, which explains the coupling of oxidation and phosphorylation through the proton gradient across the mitochondrial membrane.
π Structure and Function of ATP Synthase Complex
The second paragraph focuses on the structure and function of the ATP synthase complex, also known as Complex V, which is embedded in the inner mitochondrial membrane. It describes the complex as having two sub-complexes: the hydrophobic F0 sub-complex, which forms a proton channel, and the hydrophilic F1 sub-complex, which is exposed to the mitochondrial matrix. The F0 sub-complex is composed of a disc of 10 c protein subunits, while the F1 sub-complex consists of nine subunits, including three alpha, three beta, and three additional subunits (gamma, delta, and epsilon). The gamma subunit is highlighted as a bent axle that, along with the F0 sub-complex, rotates due to the flow of protons, a movement that is essential for ATP synthesis. The beta subunit of the F1 complex is identified as the catalytic subunit where ATP synthesis occurs. The paragraph also explains the concept of respiratory control, which links electron flow and ATP synthesis to the availability of ADP, ensuring efficient oxygen consumption based on the body's energy demands.
π Binding Change Mechanism in ATP Production
The third paragraph introduces the binding change mechanism, a theory proposed by Paul Boyer, which explains the ATP production process within the beta subunit of the F1 sub-complex. It describes how the re-entry of protons through the F0 sub-complex causes the rotation of the gamma subunit of the F1 sub-complex, leading to conformational changes in the beta subunits. These changes are crucial for the synthesis of ATP, highlighting the molecular motor aspect of the ATP synthase complex. The paragraph concludes the detailed discussion on oxidative phosphorylation, emphasizing the intricate and efficient process by which ATP is produced in the mitochondria.
Mindmap
Keywords
π‘Oxidative Phosphorylation
π‘ATP
π‘Electron Transport Chain (ETC)
π‘ADP
π‘Complex I, II, III, IV
π‘Proton Gradient
π‘ATP Synthase
π‘F0 and F1 Subcomplexes
π‘Respiratory Control
π‘Binding Change Mechanism
Highlights
Oxidative phosphorylation is the process of ATP formation during the transfer of electrons through the electron transport chain.
Energy produced from electron transfer is coupled to ATP formation by the enzyme F1F0 ATP synthase.
There are three ATP synthesizing sites in the electron transport chain: between NAD and Coenzyme Q, Coenzyme Q and cytochrome C, and cytochrome C and oxygen.
Complex 2 does not produce ATP, unlike Complex 1, 3, and 4.
The energy liberated at Complex 1 is used to synthesize one ATP molecule, as does the energy at Complex 3.
Complex 4 is responsible for pumping two hydrogen ions, resulting in the synthesis of only half an ATP molecule.
One NADH molecule entering the respiratory chain produces 2.5 ATP molecules, while one FADH2 molecule produces 1.5 ATP molecules.
The values for ATP production per NADH and FADH2 have been updated from previous assumptions.
The chemiosmotic theory by Peter Mitchell (1961) explains the coupling of oxidation and phosphorylation through a proton gradient across the mitochondrial membrane.
ATP synthase, also known as Complex V, is the smallest molecular motor in the human body, embedded in the inner mitochondrial membrane.
ATP synthase consists of two subcomplexes: F0, which forms a proton channel, and F1, which is hydrophilic and projects into the mitochondrial matrix.
The gamma subunit of the F1 complex is a bent structure that rotates along with the F0 subcomplex, driven by the proton flow.
The rotation of the F0 and gamma subunit causes conformational changes in the beta subunit of F1, where ATP synthesis occurs.
Respiratory control is the tight coupling of electron flow and ATP synthesis, ensuring oxygen consumption depends on the availability of ADP.
The binding change mechanism by Paul Boyer explains the ATP production process in the beta subunit of the F1 complex through proton re-entry and gamma subunit rotation.
ATP synthase operates as a rotor-stator molecular motor with rotating and stationary subunits.
Transcripts
[Music]
oxidative phosphorylation in the
oxidative phosphorylation we are going
to talk about the formation of ATP and
the sites of
ATP synthesis during the transfer of
electrons through the electron transport
chain energy is produced and this energy
is coupled to the formation of ATP by
phosphorylation of ADP by an enzyme f o
f1 ATP ace and the phosphorylation of
adp into ATP is coupled with oxidation
of reducing equivalents therefore the
process is called as oxidative
phosphorylation so there are totally 3
ATP synthesizing sites of the electron
transport chain site one is between nad
and coenzyme q that is complex one site
two is between coenzyme Q and the
cytochrome C which is complex 3 and site
3 is between cytochrome C and oxygen
that is complex 4 so ATP synthesizing
complexes are in the electron transport
chain they are complex world complex 3
and complex 4 complex 2 is not producing
any ATP so these sites provide energy
required to make ATP from the ADP by an
enzyme f o f1 ATP is so not an important
point here that there is no ATP
formation at the complex 2 and the
energy which is liberated at the site 1
which is called as complex 1 is used to
synthesize one ATP molecule and at the
site 2 it is also used to synthesize one
ATP molecule because the 4 hydrogen ions
which are pumped into the intermembrane
space at the complex one and complex 3
and the same hydrogen protons are pumped
back into the
the control matrix by the concentration
gradient produces ATP molecules so
whenever four hydrogen ions which are
protons whenever they are pumped back
into the mitochondrial matrix due to
their electrochemical gradient produces
one ATP molecule that is the reason
complex one produces one ATP molecule
complex three also produces one ATP
molecule now let us talk about site
three which is called as complex four so
the complex four which is known as site
three of ATP synthesis is used to
synthesize only half ATP molecule
because the complex four is responsible
for only pumping of two hydrogen ions
into the intermembrane space when these
two hydrogen ions are kicked back into
the mitochondrial matrix because of the
proton gradient which has been created
because of the electrochemical gradient
only half molecule of ATP is produced so
that's why when one NADH molecule enters
the respiratory chain it produces 2.5
molecules of ATP and in the same way
when one molecule of fadh2 enters that
has been out any chain only 1.5
molecules of ATP are produced as site 1
of energy liberation is bypassed in this
so not an important point here
previously in the previous books also it
was assumed that one NADH produces 3 ATP
and one fadh2 produces 2 ATP's but the
values has been changed now now let us
discuss in detail about the mechanism of
oxidative phosphorylation there are so
many hypotheses but the most widely
accepted as well as the most acceptable
hypothesis which explains the mechanism
of association between the oxidation of
reducing equivalents and the
phosphorylation of ADP into ATP is the
Kimmi osmotic theory which is proposed
to by the Peter Mitchell in 1961 this
theory
explains that the two processes that is
oxidation and phosphorylation are
coupled by the proton gradient across
the mitochondrial membrane so this
proton motive force caused it by the
electrochemical potential difference
that is the negative on the matrix
because the hydrogen's are pumped into
the intermembrane space drives the
mechanism of ATP synthesis let us see
exactly what is happening here let us
see the structure of complex Y which is
also called as ATP synthase complex we
know that it is the smallest molecular
motor which is present in the human body
so it is also called as v complex of
electron transport chain even though it
is separately discussed as an oxidative
phosphorylation and I already mentioned
that it is the smallest molecular motor
present in the human body so location
that is the ATP synthase is embedded in
the inner mitochondrial membrane but as
you can see it has two components or two
sub complexes we can see if not sub
complex which is also called as FO
actually called as f0 so let us say it
is called as F naught F naught sub
complex and F 1 sub complex so what is
the F 1 sub complex F 1 sub complex is
hydrophilic in nature let's discuss
about F not sub complex the F not sub
complex is hydrophobic in nature and it
spans the inner mitochondrial membrane
which means it is fixed into the inner
mitochondrial membrane any component
which is fixed into the inner
mitochondrial membrane remember that it
is the lipid one right that is the
reason we are called as hydrophobic and
it forms a proton channel and it is made
up of a disc of 10 C protein subunits so
we can see very clearly that all the C
proteins which are arranged in a circle
which forms the F naught subunit and
what is the F 1 subunit F 1 subunit or
the F
sub complex is hydrophilic in nature
because it is not embedded in the inner
mitochondrial membrane but exposed into
the mitochondrial matrix that is the
reason it is the hydrophilic in nature
because it projects into the
mitochondrial matrix and this f1 is
attached to the F o sub complex and it
is made up of totally nine subunits
these are 3 alpha 3 beta one is gamma 1
is Delta and another one is epsilon so
it is made up of totally 9 subunits and
the gamma subunit if you examine very
clearly it is in the form of a bent axle
right it is not in a straight
orientation that is the reason it is
slightly a bending structure right it is
slightly bent there's a reason we will
call it as it is slightly looks like a
bent axle so the gamma subunit which is
slightly bent structure is surrounded by
3 alpha and 3 beta subunits right and
the flow of protons through F naught
causes the rotation of F naught complex
along with the gamma subunit of the f1
complex to rotate so we can see very
clearly here as the protons are pumped
back into the mitochondrial matrix
because of their electrochemical
gradient we can see the rotation of F
not because of the rotation of F not f1
the gamma subunit of the f1 is also
rotating along with the F naught so
which one is the statical the alpha beta
subunits which are not even rotating so
they are called as stationary subunits
so this rotation actually causes the
production of ATP in the f1 complex so
the beta subunit of the f1 complex is
called as catalytic subunit because it
is the place where ATP synthesis is
taking place
so this particular ATP synthase complex
as a rotor stator molecular motor
because it has two functional units
because one is the rotating subunit what
is the rotating subunit here F or
complex and gamma subunit of the f1
complex are rotating only these two are
rotating that is the reason these are
called as rotating subunits what is the
stationary subunit the f1 complex other
than gamma subunit because gamma is also
rotating which belongs to the f1 subunit
so f1 complex other than gamma subunit
is stationary it is not rotating at all
so that is the reason in ATP synthase we
have two subunits one is called as a
static right stationary another one is
called as rotate two subunits we have
here now let us talk about what is the
respiratory control there is a tight
coupling of electron flow and ATP
synthesis in the mitochondria ensures
that oxygen consumption depends upon
availability of ADP this phenomena is
called as respiratory control so what
does it explains which means whenever we
have low ADP low ADP means high ATP it
decreases flow of electrons which
decreases oxygen consumption during rest
in the same way if the concentration of
ADP in the mitochondrial matrix is high
which means ATP is low
it increases flow of electrons which
increases oxygen consumption which means
whenever we are exercising whenever our
body demands of oxygen increases
electron flow also increases now let us
talk about a new theory called as
binding change mechanism so here the
theory behind the ATP production in the
beta subunit of the f1 sub complex is
proposed mainly by Paul Boyer it states
that the re-entry of protons through the
F knot sub complex causes rotation of
the gamma subunit of
the f1 sub complex which in turn causes
conformational change in the beta
subunits of the f1 sub complex this is
called as binding change mechanism by
this we completed in detail about the
oxidative phosphorylation and in this we
also discussed about how the ATP
synthesis is taking place by means of a
complex molecular motor
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