metabolisme problem

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kabuto
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metabolisme problem

Post by kabuto » Wed Apr 12, 2006 2:34 pm

how many molecules of ATP is formed when lactate is catabolized via Krebs cycle?

how is lactate converted to pyruvate or is it to acetly CoA?

i know that the part from pyruvate until krebs cycle.
pyruvate-->acetyl CoA(1 NADH=3ATP)
acetyl CoA--> Krebs (3NADH=9ATP, 1FADH2=2ATP, 1GTP=1ATP)
total=3+9+2+1=15ATP

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Enzyme
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Post by Enzyme » Wed Apr 12, 2006 5:41 pm

Lactate is converted to pyruvate (by NAD+ dependent lactate dehydrogenase). Pyruvate is converted to Acetyl CoA and then, this pass to Krebs' Cycle.

The aerobic catabolization of lactate generates the formation of 17 ATP.
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Post by kabuto » Thu Apr 13, 2006 7:53 am

thanks, enzyme

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Post by kiekyon » Thu Apr 13, 2006 8:33 am

Enzyme wrote:Lactate is converted to pyruvate (by NAD+ dependent lactate dehydrogenase). Pyruvate is converted to Acetyl CoA and then, this pass to Krebs' Cycle.

The aerobic catabolization of lactate generates the formation of 17 ATP.


can u show us the calculation, please..

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Enzyme
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Post by Enzyme » Thu Apr 13, 2006 10:54 am

kabuto wrote:thanks, enzyme


You're welcome ;).
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Post by sdekivit » Fri Apr 14, 2006 12:10 pm

kiekyon wrote:
Enzyme wrote:Lactate is converted to pyruvate (by NAD+ dependent lactate dehydrogenase). Pyruvate is converted to Acetyl CoA and then, this pass to Krebs' Cycle.

The aerobic catabolization of lactate generates the formation of 17 ATP.


can u show us the calculation, please..


look in the table in metabolism: lactate is converted to pyruvate by lactate dehydrogenase and yield 1 NADH (2,5 ATP)

then pyruvate is metabolized in de krebscycle yielding:
4 NADH = 10 ATP
1 FADH2 = 1,5 ATP
1 GTP = 1 ATP

total = 12,5 ATP + 2,5 ATP = 15 ATP

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Post by scottyiu » Fri Apr 14, 2006 2:21 pm

Is their any way to increase or decrease the rate of metabolisme?
This forum is so cool

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kabuto
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Post by kabuto » Sat Apr 15, 2006 12:54 pm

is it 15 or 17??
:?: :?: :?: :?:

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Post by sdekivit » Sat Apr 15, 2006 4:46 pm

15 is the correct answer, i don't know where the 2 ATP from enzyme came from.

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Enzyme
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Post by Enzyme » Sun Apr 16, 2006 4:04 pm

Hey, thanks for the correction! ;)

Sorry, I have read again my post answering kabuto's question and I've seen that I wrote: '17 ATP'. I wanted to mean '18 ATP'. I didn't see the mistake before.

The explanation of my answer is because I did the calculations basing me in the next equivalences:

1 NADH = 3 ATP.
1 FADH2 = 2 ATP.
1 GTP = 1 ATP.

When lactate is converted to pyruvate, one NAD+ is reduced to NADH. So the value in ATP molecules (taking in account the equivalences shown at the top of this paragraph) is 3 ATP.

So my point of view would be:

1. Lactate ---> Pyruvate [1 NADH = 3 ATP]
2. Pyruvate ---> Acetyl CoA [1 NADH = 3 ATP]
3. Krebs' cycle [3 NADH = 9 ATP, 1 FADH2 = 2 ATP and 1 GTP = 1 ATP]

In conclusion:

3 ATP + 3 ATP + 9 ATP + 2 ATP + 1 ATP = 18 ATP

The true values in ATP molecules of NADH and FADH2 are 2.5 and 1.5 respectively. But for questions of a better teaching or I don't know, many people round up the values to 3 and 2 respectively. For that I based my explanation on those values.

Thanks for the correction again ;). See you! ;)
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Post by Eolian1701 » Mon Apr 17, 2006 8:43 pm

But don't forget that there are TWO pyruvates that enter into the cycle for each glucose molecule. So do you double the number of ATP's for glucose or are you looking for just ONE pyruvate?

Eolian

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Post by Enzyme » Mon Apr 17, 2006 11:32 pm

Eolian1701 wrote:But don't forget that there are TWO pyruvates that enter into the cycle for each glucose molecule. So do you double the number of ATP's for glucose or are you looking for just ONE pyruvate?

Eolian


My explanation is for one pyruvate (1 malate ---> 1 pyruvate). But thanks Eolian for your statement.
Last edited by Enzyme on Tue Apr 18, 2006 9:57 am, edited 2 times in total.
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