Lecture 28 - beta oxidation of fatty acids Flashcards

1
Q

What is the overall reaction for beta oxidation

A

Cn-ACYL-CoA + FAD + NAD+ + H2O + CoA

Cn-2-ACYL-CoA + FADH2 + NADH + H+ + ACETYL-CoA

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2
Q

What happens to the acetyl-CoA produced?

A

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

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3
Q

What is the Overall reaction for the TCA cycle

A

Acetyl-CoA + 3 NAD+ + FAD + GDP + Pi + 2H2O —>

2 CO2 + 3 NADH + 3H+ + FADH2 + GTP + CoA
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4
Q

What is the total production from the 8 acetyl CoAs from palmitate

A

8 x 3 = 24 NADH + H+
8 x 1 = 8 FADH2
8 x 1 = 8 GTP

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5
Q

What is the rough efficiency of beta oxidation of FA

A

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%

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6
Q

What is the yield per carbon oxidised to CO2

A

No. of ATP = 129 = ~8.2
No. of carbons 16

Equivalent figure for glucose is ~6.3

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7
Q

When are ketone bodies not always present in large enough quantities

A

Fasted periods

Oxaloacetate is needed for entry of acetyl-CoA into the TCA cycle

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8
Q

Where are ketone bodies mainly produced

A

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

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9
Q

Why are ketone bodies considered “energy rich”

A

Water soluble – so easily transported in the blood

Easily broken down

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10
Q

What are the major users of ketone bodies

A

Heart and renal cortex

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11
Q

Ketone body formation in mitochondria

A

SLIDES 21-24

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12
Q

Ketone body utilisation

A

slides 25-27

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