Sorry, but I don't get it
I thought I was supposed to count the oxidation numbers for carbon (I was looking at the Bentley paper and how it described that all the interesting stuff in NAD+ reduction really took place on the carbons and not the charged nitrogen atom). If I'm also counting for oxygen I get confused because then I don't know how to pick out one from the other - as you say in a carboxyl group the electrons 'belong' to the oxygen. But that's sorted by giving them away as per the formula.
I know that it's the oxygen atom that has the charge, but I still have to include that charge somehow. You're right that it says in table III that carbon has an oxidation number of +3, but shouldn't that be something that can be shown from the formula without having to look it up?
So I don't know if I'm supposed to count for both oxygen and carbon now (and if so, also any other atom in the molecule I suppose). I understood the trick as simply seeing whether carbon 'owned' or didn't own the electrons and then adding charges for each group.
Maybe it's just because I don't really get what I'm counting. From I understand redox reactions the whole point is not just the transfer of electrons but the energy level of said electrons (thereby transfering energy with them), and that depends on the bonds.. thus I'm confused about how one can keep score simply by tallying in this way.
But then again, I can't figure that out anyway.
Ignoring that, isocitrate would then be:
+3; -2; -1; +3; +0; +3; making the oxidation number 6
doing the same with alpha-ketoglutarate:
+3; -2; -2; +2; +3; making the oxidation number 4, so it still doesn't add up, does it? Considering we also have a CO2 to account for. Ugh, chemistry.