Bridging Step of Krebs Cycle oxidatiion or reduction?

[jenzao]

Bridging Step of Krebs Cycle...oxidatiion or reduction?

I am told that the following reaction is a oxidative decarboxylation:

pyruvate +CoA + NAD+ ---> acetyl CoA + CO2 + NADH

but NAD+ is reduced to form NADH...

Do we call it an oxidation because we are interested in what happens to the pyruvate or am i missing something?

 

[Ygggdrasil]

In any redox reaction, one species will be reduced while the other will be oxidized. So, you are absolutely correct that this reaction results in the oxidation of pyruvate and the reduction of NAD⁺. It is called an oxidation because in glycolysis, we are interested in what happens to the original molecule of glucose that gets consumed by the cell. NAD⁺ is just considered a cofactor that helps the reaction along, despite the important role it plays in energy generation in the electron transport chain.