Question

During fatty acid activation high energy bonds are broken and new high energy bonds are formed. Calculate the energy cost of the process.

Answer 1

Step 1.- Number of Carbons/2 = Number of Acetyl CoA formed.

Step 2.- Number of rounds in the Beta-oxidation necessary for converting the whole fatty acid to Acetyl Co A units: Number of Acetyl CoA minus 1 [(n/2)-1]

Step 3 (Option a) If you consider that each NADH yields 2.5 ATP and each FADH2 yields 1.5 ATP then multiply the number of rounds times 4 and multiply the number of Acetyl CoA times 1o

OR

Step 3 (Option b).- If you consider that each NADH yields 3 ATP and each FADH2 yields 2 ATP then multiply the number of rounds times 5 and multiply the number of Acetyl CoA times 12.

Step 4.- Take two ATP that were used for the activation of the Fatty Acid

Example:

Fatty acid with 12 Carbons

Option (a):

Step 1: 12/2 = 6 Acetyl CoA

Step 2: 6-1 = 5 rounds

Step 3 (Option a): (5 x 4) + (6 x10)

Step 4 = -2

Total: 78 ATP

– Option (b):

Step 1: 12/2 = 6 Acetyl CoA

Step 2: 6-1 = 5 rounds

Step 3 (Option b): (5 x 5) + (6 x12)

Step 4 = -2

Total: 95 ATP