Pyruvate oxidation

Pyruvate Oxidation

Pyruvate Oxidation is the step which connects glycolysis to Krebs Cycle. It takes the two pryuvate molecules formed during glycolysis and transports them from the cytoplasm, through the two mitochondrial membranes into the mitochondrial matrix. Once inside, a multienzyme complex known as the pyruvate dehydrogenase complex catalyzes these changes:

1. A carboxyl group is removed as CO₂, which diffuses out of the cell. As a result, the original pyruvate has now been converted into a two-carbon hydroxyethyl group.
2. The remaining two-carbon hydroxyethyl group has now been oxidized to an acetyl group.
3. A NAD+ accepts the electrons removed during the oxidation and is thereby reduced by two hydrogen atoms.
4. The acetyl group becomes attached to Coenzyme A yeilding acetyl-CoA.
5. The newly formed acetyl-CoA now moves on to Krebs Cycle.
6. NAD+ is reduced to NADH as the third enzyme of the pyruvate dehydrogenase complex restores the second enzyme's lipoamide to its oxidized state.