Cholesterol synthesis

Features of cholesterol synthesis

  • Acetate of acetyl CoA provides all carbons
  • Reducing equivalents are supplied by NADPH and ATP provides energy
  • For producing 1 mole of cholesterol, 18 moles of acetyl CoA, 36 moles of ATP and 16 moles of NADPH are required.

There are 5 stages in synthesis of cholesterol

  • 2 moles of acetyl CoA combine to form acetoacetylCoA
  • Again a mole of acetyl CoA is added to form HMG CoA
  • HMG CoA reductase (rate limiting enzyme) catalyses the reduction of HMG CoA to mevalonate
  • Mevalonate is converted to 3-phospho5-PPM after 3 step reactio
  • 3-phospho-5-PPM on decarboxylation forms Isopentenyl PP
  • IPP isomerizes to form dimethylallyl PP
  • Geranyl PP is formed by condensation of isopentenyl PP and dimethylallyl PP
  • GPP condenses with IPP to form Farnesyl PP
  • 2 units of Farnesyl PP unite and get reduced to form squalene
  • After undergoing hydroxylation &cyclization Utilizing O2 and NADPH squalene gets converted to lanosterol.
  • Lanosterol after 19 enzymatic reactions forms cholesterol.

A way to remember this –

Ariana & Adele with Calvin Harris made a Music video at 5 places on an Island, deserted and green feat. Sharks,lobsters and crabs!

Ariana-Acetyl CoA

Adele-Acetoacetyl CoA

Calvin Harris-HMG CoA

Music video-Mevalonate

5Places-   5Phosphomevalonate

Island – Isopentenyl PP

Deserted-Dimethylallyl PP

Green-Geranyl PP

Featuring-Farnesyl PP

Sharks-squalene

Lobsters-lanosterol Crabs-cholesterol

 

Hope this helps!

-Anuja Mandavkar, Jay Shah

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