The Revised Chemiosmotic Theory (2013)

by Irham Kasyful Minggu, Februari 24, 2013 3 komentar

In this article, i am trying to explain about The Electron Transport System in mitochondria.

One of the question that tingling my mind is "how many ATP produced in aerobic respiration?" By the time i have read some source, it says 36/38 ATP and also the other says 30/32 ATP. So how can we explain this?"

Let's first I tell you about my day. One day, I got a case from my tutorial class, this case talks about Obesity and Hypercholesterol in a patient. This is the study method in medical faculty, we got one case every week, we study from the case first and slowly begin to reach the basic science, which is related to the case. We were forced to understand the basic science, so we can solve the problem. This is important because, phylosophically, in doctor's daily life, they always facing the cases from their patient.

So, lets begin..
Respiration is one of the process in organism to gain energy. It's so special because this kind of process gain the biggest energy rather than the other.
Divided into four step : Glycolisis, Oxidative Decarboxialtion, Kreb cycle/TCA cycle, and Electron Transport System (ETS)
(also, some said only three step, they grouped DO into TCA cycle, whatever it is, the reaction still the same)

and the ATP result :

from Campbell Biology

but, look at this too :

from Lehninger Biochemistry

The question is :

Which one is true? 36/38 atp or 30/32 ATP?
The difference also makes me confused. Until i try to figure out what is going on and then realize that "book released in 2006 and later" did some kind of revision saying "ATP produced in one complex oxidation process result 30/32 atp" (not 36/38 atp).

And, how could this revision was made? 
The key to understand this is to know in detail about Electron Transport System process, the complexities of how 1,2,3 and 4 transport system works together. The main distinction is actually come from the change of how NADH / FADH release H+ and produce ATP.

the 'new' revised chemiosmotic theory :

the 'old' theory :

Until now, some recent books use the new theory. So we conclude:

NADH gain 10 H+

FADH gain 6 H+ 

Next question, why one Hidrogen Ion produce 2.5 ATP? How can it is not an integer number like maybe 1 or 2 ATP?
The old theory said 1 H+ will pass ATP synthase protein system and produce 1 ATP, but now it says the system is not like that anymore. Take a look inside the new theory of ATP Synthase protein system:

Some new properties I found for the ATP synthase system :

• ATP synthase is comprised of F1 and F0 molecule. F1 is alpha and beta component, and F0 is C component. Where H+ will be inserted in C component, so the C component can rotate.
• There are 12 slots for hidrogen ion in C component to be inserted. Hidrogen has to fulfill the slot so it can rotate.
• When C component rotates 360 degrees, the ATP synthase resulting 2.5 ATP.

Then, the conclusion is:

1 rotation = 3 ATP

1 rotation = need 12 hydrogen ion

12 H = 3 ATP  ->  4 H = 1 ATP

 NADH = resulting 10 H

(10 H / 4 H) * 1 ATP = 2.5 ATP

FADH = resulting 6 H

(6 H / 4 H) * 1 ATP = 1.5 ATP

Still, this is not even a new theory, this information can change over time replaced with newer information further. You need to read other updated resource as well guys.


reference :
Whitney Ellie, 2008, Understanding Nutrition 11th edition
Murray Robert K., 2009, Harper's Illustrated Biochemistry 28th edition

"this article was made and to be devoted for my beloved teacher miss Dewi K.S"