Intermediate products of energy metabolism

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

Creation

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

• 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

Pyruvate

Creation

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

Usage

• 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

NAD⁺ – NADH

Creation

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

Usage

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

Link

• ws:Meziprodukty energetického metabolismu