12.04 Link Reaction

Purpose

• Links glycolysis to the Krebs cycle by converting pyruvate into acetyl CoA in the mitochondrial matrix.

Steps in the Link Reaction

1. Pyruvate Conversion:

• Decarboxylation: Removal of CO₂ from pyruvate.
• Dehydrogenation: Removal of hydrogen from pyruvate, which reduces NAD to NADH.
• Formation of Acetyl CoA: The remaining 2-carbon molecule combines with Coenzyme A (CoA) to form acetyl CoA.

1. Coenzyme A (CoA):

• Structure: Composed of adenine, ribose, and vitamin B5 (pantothenic acid).
• Function: Acts as a carrier, transporting acetyl groups necessary for the Krebs cycle (converts oxaloacetate to citrate).

Equation for the Link Reaction

• Overall Reaction:
  Pyruvate + CoA + NAD⁺ → Acetyl CoA + CO2 + NADH

Key Points

• Products per pyruvate: 1 acetyl CoA, 1 CO₂, 1 NADH.
• Location: Mitochondrial matrix