Intermediate products of energy metabolism

From WikiLectures

In cells, there are metabolic pathways – a kind of crossroads of mutual transformation of nutrients. These include the ``pyruvate dehydrogenase reaction' (PDH), the ``Krebs cycle (KC) and the respiratory chain (DŘ). Three intermediates, acetyl-CoA, pyruvate' and NADH, have an important position in energy metabolism.

Acetyl-CoA[edit | edit source]

Acetyl-CoA

Creation[edit | edit source]

Pyruvate dehydrogenase reaction (PDH)
The irreversibility of this reaction is the reason that glucose cannot be formed from the vast majority of fatty acids.
Degradation of amino acids
Lysine and leucine are degraded directly to acetyl-CoA, other amino acids are converted via pyruvate.
β-oxidation of fatty acids and degradation of ketone bodies.

Usage[edit | edit source]

  • The Krebs cycle, which is followed by the respiratory chain (and ATP production).
  • Synthesis of fatty acids and ketone bodies (with an excess of acetyl-CoA).
  • Cholesterol synthesis.

Pyruvate[edit | edit source]

Pyruvate

Creation[edit | edit source]

  1. Aerobic glycolysis.
  2. Lactate oxidation (catalyzed by lactate dehydrogenase).
  3. Degradation of some AKs.

Usage[edit | edit source]

  • Synthesis of acetyl-CoA (PDH).
  • Lactate synthesis – takes place during anaerobic glycolysis, the purpose of which is to regenerate reduced coenzymes NADH + H+ back to NAD+.
  • Alanine synthesis (catalyzed by alanine aminotransferase).
  • Synthesis of oxaloacetate (catalyzed by pyruvate carboxylase).
  • Gluconeogenesis.

NADH[edit | edit source]

NAD+ – NADH

Creation[edit | edit source]

  1. Aerobic glycolysis
  2. Pyruvate dehydrogenase reaction.
  3. Beta-oxidation of fatty acids.
  4. Krebs cycle.
  5. Oxidation of ethanol.

Usage[edit | edit source]

  • The respiratory chain and the formation of ATP.
  • Conversion of pyruvate to lactate.

Link[edit | edit source]