Food Chemistry and Fish in Nutrition

4.3.6. Syntesis of Cholesterol

4.3.6. Synthesis of Cholesterol

Cholesterol is made from acetyl CoA. Three molecule of acetyl CoA combine to yield mevalonate, which becomes phosphorylated to 3- phosphor-5- pyrophospho-mevalonate.

Thiolase

Acetyl CoA + acetyl CoA → Acetoacetyl CoA + CoA

Synthase

Acetoacetyl CoA + acetyl CoA + H₂O→ 3 hydroxy 3methylglutaryl CoA + CoA + H⁺

Hydroxmethyl glutaryl CoA reductase

3 hydroxy 3methylglutaryl CoA + 2NADPH + 2H⁺ → mevalonate + CoA +2NADP⁺

On the loss of CO2 and phosphate, 3-isopentenyl pyrophosphate is formed. Stepwise assembly of six molecules of the latter ultimately yields the linear hydrocarbon squalene. It then cyclizes to form lanosterol, which is then converted to cholesterol. Cholesterol synthesis is inhibited by dietary cholesterol.