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Topic: How is this H+ ion bonded when NAD becomes NADH +H+ ?  (Read 4334 times)

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Offline John623

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How is this H+ ion bonded when NAD becomes NADH +H+ ?
« on: April 12, 2015, 03:16:42 AM »
First of all: I keep finding two equations that are supposedly showing the same reaction:
1) NAD+ +2e +H+ -> NADH
2) NAD+ +2e +2H+ -> NADH +H+

The first one suggests NAD carries around 2 electrons and one hydrogen ion
The second one suggests NAD carries around 2 electrons and 2 hydrogen ions

I imagine that the second equation shows an extra H+ ion (when compared to the first one) because for some reason a H+ ion follows the NADH around. Is it because a H+ ion forms a co-dative bond with the NADH (allowing it to 'carry' around 2 H+ ions?).

If the second H+ doesn't form a codative bond with the NADH, then what kind of bond does it form that allows it to follow the NADH around instead of just diffusing away?

Offline Hunter2

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Re: How is this H+ ion bonded when NAD becomes NADH +H+ ?
« Reply #1 on: April 12, 2015, 02:12:22 PM »
Theoretically it can be add as ammonium to the nitrogen

http://de.wikipedia.org/wiki/Nicotinamidadenindinukleotid


Offline John623

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Re: How is this H+ ion bonded when NAD becomes NADH +H+ ?
« Reply #2 on: April 13, 2015, 02:50:48 AM »
So the H+ ions that are released into solution when glucose becomes pyruvate, and when pyruvate becomes Acetyl-CoA, end up becoming ammonia?

Offline Babcock_Hall

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Re: How is this H+ ion bonded when NAD becomes NADH +H+ ?
« Reply #3 on: April 13, 2015, 09:35:25 AM »
Your two equations are really the same one, as can be seen by canceling a proton from each side of equation 2.  The reduced form of NAD, which is NADH, does not carry a second proton, not having any group with an appropriate pKa.  (I would include a negative sign on the electron, but I am not sure that everyone would.)  How is intracellular pH maintained?  Is the cytoplasm buffered in any way?

Offline John623

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Re: How is this H+ ion bonded when NAD becomes NADH +H+ ?
« Reply #4 on: April 13, 2015, 11:55:33 AM »
Well, the cytoplasm does have buffers.

I believe that when 1 glucose (12 hydrogens) is turned into ATP:
2 pyruvic acids(4H) are created, which turn into 2 pyruvates(3H) + 2H+
Also, 2 NADH +2H+ are created.

So end up with 4H+ being released into solution. I imagine that these could bind to a buffer.

If this is the case what happens to the buffer when it has taken all the hydrogen ions it can handle? Are they excreted, destroyed, or shipped somewhere else so that the H+ can be released to bind with negative ions somewhere else in the body?

Offline Babcock_Hall

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Re: How is this H+ ion bonded when NAD becomes NADH +H+ ?
« Reply #5 on: April 13, 2015, 03:25:47 PM »
You may wish to recalculate your numbers for pyruvate, given that its structure is CH3C(O)CO2-.  I would also consult a balanced equation for glycolysis at some point, to make sure that I had not missed anything.

Offline John623

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Re: How is this H+ ion bonded when NAD becomes NADH +H+ ?
« Reply #6 on: April 14, 2015, 05:57:10 AM »
Are my hydrogen numbers wrong?
glucose = 12
pyruvates = 3; 2*3 = 6
NADH takes 2
total missing: 4H+ because 12-8 = 4H

I was just trying to work out where these missing 4H+ are going

Offline Babcock_Hall

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Re: How is this H+ ion bonded when NAD becomes NADH +H+ ?
« Reply #7 on: April 14, 2015, 10:03:36 AM »
Have you looked up the balanced equation for glycolysis.  I think you are missing the formation of water.

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