Lecture 28 - beta oxidation of fatty acids Flashcards
What is the overall reaction for beta oxidation
Cn-ACYL-CoA + FAD + NAD+ + H2O + CoA
Cn-2-ACYL-CoA + FADH2 + NADH + H+ + ACETYL-CoA
What happens to the acetyl-CoA produced?
Enters the TCA cycle
OR
Made into ketone bodies
Most goes into the TCA cycle unless there is a shortage of carbohydrate/a lot of fatty acid metabolism
What is the Overall reaction for the TCA cycle
Acetyl-CoA + 3 NAD+ + FAD + GDP + Pi + 2H2O —>
2 CO2 + 3 NADH + 3H+ + FADH2 + GTP + CoA
What is the total production from the 8 acetyl CoAs from palmitate
8 x 3 = 24 NADH + H+
8 x 1 = 8 FADH2
8 x 1 = 8 GTP
What is the rough efficiency of beta oxidation of FA
Energy captured is 129 times the Free energy of hydrolysis of one phosphate from ATP
129 x -31kJ/mole = -3999kJ/mole
Standard Free energy of oxidation of palmitate
-9790kJ/mole
Proportion of energy captured = -3999/-9790 = ~40%
What is the yield per carbon oxidised to CO2
No. of ATP = 129 = ~8.2
No. of carbons 16
Equivalent figure for glucose is ~6.3
When are ketone bodies not always present in large enough quantities
Fasted periods
Oxaloacetate is needed for entry of acetyl-CoA into the TCA cycle
Where are ketone bodies mainly produced
Liver
Oxaloacetate being used for glucose synthesis (gluconeogenesis)[so not available to allow acetyl-CoA into TCA cycle]
Major site of key enzymes of ketone body synthesis
Why are ketone bodies considered “energy rich”
Water soluble – so easily transported in the blood
Easily broken down
What are the major users of ketone bodies
Heart and renal cortex
Ketone body formation in mitochondria
SLIDES 21-24
Ketone body utilisation
slides 25-27