Beta Oxidation - Energy Yield

Energy Yield

The ATP yield for every oxidation cycle is 14 ATP (according to the P/O ratio), broken down as follows:

Source ATP Total
1 FADH2 x 1.5 ATP = 1.5 ATP (some sources say 2 ATP)
1 NADH x 2.5 ATP = 2.5 ATP (some sources say 3 ATP)
1 acetyl CoA x 10 ATP = 10 ATP (some sources say 12 ATP)
TOTAL = 14 ATP

For an even-numbered saturated fat (C2n), n - 1 oxidations are necessary, and the final process yields an additional acetyl CoA. In addition, two equivalents of ATP are lost during the activation of the fatty acid. Therefore, the total ATP yield can be stated as:

(n - 1) * 14 + 10 - 2 = total ATP

For instance, the ATP yield of palmitate (C16, n = 8) is:

(8 - 1) * 14 + 10 - 2 = 106 ATP

Represented in table form:

Source ATP Total
7 FADH2 x 1.5 ATP = 10.5 ATP
7 NADH x 2.5 ATP = 17.5 ATP
8 acetyl CoA x 10 ATP = 80 ATP
Activation = -2 ATP
NET = 106 ATP

For sources that use the larger ATP production numbers described above, the total would be 129 ATP ={(8-1)*17+12-2} equivalents per palmitate.

Beta-oxidation of unsaturated fatty acids changes the ATP yield due to the requirement of two possible additional enzymes.

Read more about this topic:  Beta Oxidation

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