Cholesterol Synthesis

Question 0

Step 2: Reduction of HMG CoA

2(NADPH + H) {from Pentose Pathway} + HMG CoA ->

Answer 0

2NADP + CoASH + Mevalonate (6-Carbon Acid)

Enzyme: HMG Reductase

Regulated by controlling levels of enzyme, statins are comp inhibitors

Question 1

Step 1: Synthesis of HMG CoA (difference from ketone body synth)

Acetyl CoA + Acetoacetyl CoA ->

Answer 1

3-Hydoxyl-3-methylglutaryl CoA

OCCURS IN ALL TISSUE. Ketones in mitochondria in Liver

Occurs all the time, not just when fasting.

Question 2

Step 3:

Mevalonate + 3ATP ->

Answer 2

Isopentenyl Pyrophosphate + 3ADP + Pi + CO2

Question 3

Step 4:

6 (isopentyl Pyrophosphate) ->

Answer 3

Squalene (30 Carbons)

First on the committed pathway to cholesterol

Question 4

Step 5:

Squalene + O2 + NADPH + H ->

Answer 4

-> Squalene- 2,3-oxide + NADP+ H2O
Enzyme: Squalene Monoonygenase

S-2,3-O -> Lanosterol (C30)
Enzyme: S-2,3,-O Cyclase

Question 5

Step 6

Lanosterol + lots of O2->

Answer 5

Cholesterol (C27)