4.2 Pyruvate Oxidation

• Extraction of the remaining free energy in the pyruvate molecules from glycolysis (& the citric acid cycle)

• DECARBOXYLATION – removal of carboxyl group (COO-)

  • Released as CO2 (waste)

  • Turns Pyruvate → acetyl group

  • 1/3rd of CO2 we exhale

  • Followed by oxidation of the remaining two carbon molecules, producing an acetyl group

• DEHYDROGENATION

  • Transfers 2e and 1p o NAD+ → NADH

  • Releases H+ into solution (extra)

  • Acetyl bonds to coenzyme A →ACETYL-COA

2 pyruvate + 2 NAD+ + 2 CoA → acetyl-CoA + 2 NADH + 2 H+ + 2 CO2

• Large pores in outer membrane allow pyruvate through

• For inner membrane a pyruvate specific membrane carrier is required

• Once in the matrix, it converts into an acetyl group

• which is then temporarily bonded to a sulfur atom on the end of a large molecule called coenzyme A, or CoA.

• The result is an acetyl-CoA complex.

So far...

Glycolysis yields:

• 2 ATP (net)

• 2 NADH

Pyruvate Oxidation yields:

• 2 NADH (1 for each pyruvate)

• Isnt acetylcoa a yield??

Now, acetyl-CoA enters the citric acid cycle