September 18, 2019, 05:54:10 AM
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Topic: Why is CO2 a by-product of NAD+ reactions in the Kreb's cycle?  (Read 1925 times)

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Offline BryanC

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Why is CO2 a by-product of NAD+ reactions in the Kreb's cycle?
« on: September 05, 2018, 06:15:24 AM »
NAD+ is reduced to NADH in the reactions below:

Pyruvate oxidation
NAD+ + pyruvate + CoA -> NADH + H+ + CO2 + Acetyl-CoA

3rd step of Kreb's cycle
NAD+ + Isocitrate -> NADH + H+ + CO2 + α-ketoglutarate

4th step of Kreb's cycle
NAD+ + α-ketoglutarate + CoA -> NADH + H+ + CO2 + Succinyl-CoA

Is there a reason why CO2 is produced when there is a reduction of NAD+?

The texts I have so far simply state that CO2 is derived from the carbon atom that is lost in the hydrocarbon molecule. However, that doesn't seem to explain the core reason why this happens.

Offline Arkcon

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Re: Why is CO2 a by-product of NAD+ reactions in the Kreb's cycle?
« Reply #1 on: September 05, 2018, 08:25:15 AM »
If you get a reduction, how is that accomplished?  What causes a reduction?  https://en.wikipedia.org/wiki/Citric_acid_cycle#Steps
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline Babcock_Hall

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Re: Why is CO2 a by-product of NAD+ reactions in the Kreb's cycle?
« Reply #2 on: September 05, 2018, 10:49:10 AM »
I think it helps to assign oxidation numbers to carbon atoms and to tally up electrons.

Offline Babcock_Hall

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Re: Why is CO2 a by-product of NAD+ reactions in the Kreb's cycle?
« Reply #3 on: September 11, 2018, 09:03:54 AM »
ON (C) = (number of bonds to O, N, etc) - (number of bonds to H). 

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