Did you know? Pyruvate is converted to Acetyl CoA with the Pyruvate Dehydrogenase Complex!
The PDHC is made up of 3 seperate enzymes, and uses 5 different coenzymes (TPP, FAD, CoA, NAD, and Lipoate)
TPP is used in decarboxylases and transketolases as well. It acts as an “electron sink: and creates a carbanion, which can act as a nucleophile, which will attack carbonyl group (in pyruvate in this case) and essentially “steal” two carbons, so that it can transfer them. THis is the E1 unit that does this and the next part(pyruvate dehydrogenase)
TPP transfers two carbons from pyruvate to lipoic acid in this case, attached to the E2 subunit. Lipoic acid is attached to a Lysine, which acts as a sort of long chain that can move between different areas in the complex. E2 swings from E1 after getting the acylated form of lipoic acid. E2 is Pyruvate transacetylase.
CoA has pantothenic acid as part of what makes it up. CoA, unlike lipoic acid, is not a prosethti group. it is “grabbed” by enzymes, and then released. The active thiol group is what reacts with the aceyl group on Acylated Lipoic Acid.
At this point, Acetyl CoA is made, but Lipoic acid is now in a reduced form which is a problem ( I think?) so its gotta be oxidized.
FAD and NAD+ I think are used to do this. FAD can either oxidize by 1 or 2, where NAD+ must be 2.
So, FAD comes in and takes two Hs from the lipoic acid to make FADH2, and NAD+ takes those and makes NADH + H+ This is at E3 (dihydrolipoyl dehydrogenase I think?)
I think thats it?