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Stearic Acid Beta Oxidation ATP Yield
Related Discussion on ATP Yield from β-Oxidation of Stearic Acid
Metabolism of fatty acid is related to the energy supply of life. Stearic acid is a long-chain saturated fatty acid, and its β-oxidation process is complicated and orderly, and is closely related to the generation of ATP.
Stearic acid contains octadecarbon. Through the β-oxidation pathway, two carbon units can be broken off in each round to generate one molecule of acetyl-CoA, one molecule of FADH -2 and one molecule of NADH. In the first round of β-oxidation, stearoyl-CoA is catalyzed by lipoyl-CoA dehydrogenase to generate trans-delta ² -oleoyl-CoA and FADH ³. In this step, FAD is reduced by receiving hydrogen. Then trans-delta ² -oleoyl-CoA is catalyzed by hydration enzyme to add water to form L ( + ) - β - hydroxylioyl-CoA, and then under the action of β-hydroxylioyl-CoA dehydrogenase, β-ketoyl-CoA and NADH are generated. NAD is obtained by receiving hydrogen. The final β-ketoacyl-CoA is catalyzed by thiolase and interacts with CoA-SH to cleave into one molecule of acetyl-CoA and fatty acyl-CoA with less carbons than orthoacyl-CoA.
After eight rounds of β-oxidation of stearic acid, nine molecules of acetyl-CoA, eight molecules of FADH -2 and eight molecules of NADH can be obtained. Acetyl-CoA is completely oxidized into the tricarboxylic acid cycle, and one molecule of acetyl-CoA can generate 10 molecules of ATP through this cycle. FADH and NADH are oxidized and phosphorylated by the respiratory chain to generate ATP. FADH can generate 1.5 molecules of ATP through the respiratory chain, and NADH can generate 2.5 molecules of ATP.
Therefore, the total amount of ATP produced by the oxidation of stearic acid β-CoA is: the number of ATP produced by nine molecules of acetyl-CoA, that is, 9 × 10 = 90; the number of ATP produced by eight molecules of FADH -2, that is, 8 × 1.5 = 12; and the number of ATP produced by eight molecules of NADH, that is, 8 × 2.5 = 20. The sum of the three, 90 + 12 + 20 = 122. However, when stearic acid is activated into stearyl-CoA, two high-energy phosphate bonds in one molecule of ATP are consumed, which is equivalent to the consumption of 2 molecules of ATP, so the net ATP generated by the oxidation of stearic acid β-oxidation is 122-2 = 120.
From this point of view, the oxidation of stearic acid β-oxidation provides energy to the body. This process is delicate and rigorous, and it is crucial for maintaining the energy requirements of life activities.
Metabolism of fatty acid is related to the energy supply of life. Stearic acid is a long-chain saturated fatty acid, and its β-oxidation process is complicated and orderly, and is closely related to the generation of ATP.
Stearic acid contains octadecarbon. Through the β-oxidation pathway, two carbon units can be broken off in each round to generate one molecule of acetyl-CoA, one molecule of FADH -2 and one molecule of NADH. In the first round of β-oxidation, stearoyl-CoA is catalyzed by lipoyl-CoA dehydrogenase to generate trans-delta ² -oleoyl-CoA and FADH ³. In this step, FAD is reduced by receiving hydrogen. Then trans-delta ² -oleoyl-CoA is catalyzed by hydration enzyme to add water to form L ( + ) - β - hydroxylioyl-CoA, and then under the action of β-hydroxylioyl-CoA dehydrogenase, β-ketoyl-CoA and NADH are generated. NAD is obtained by receiving hydrogen. The final β-ketoacyl-CoA is catalyzed by thiolase and interacts with CoA-SH to cleave into one molecule of acetyl-CoA and fatty acyl-CoA with less carbons than orthoacyl-CoA.
After eight rounds of β-oxidation of stearic acid, nine molecules of acetyl-CoA, eight molecules of FADH -2 and eight molecules of NADH can be obtained. Acetyl-CoA is completely oxidized into the tricarboxylic acid cycle, and one molecule of acetyl-CoA can generate 10 molecules of ATP through this cycle. FADH and NADH are oxidized and phosphorylated by the respiratory chain to generate ATP. FADH can generate 1.5 molecules of ATP through the respiratory chain, and NADH can generate 2.5 molecules of ATP.
Therefore, the total amount of ATP produced by the oxidation of stearic acid β-CoA is: the number of ATP produced by nine molecules of acetyl-CoA, that is, 9 × 10 = 90; the number of ATP produced by eight molecules of FADH -2, that is, 8 × 1.5 = 12; and the number of ATP produced by eight molecules of NADH, that is, 8 × 2.5 = 20. The sum of the three, 90 + 12 + 20 = 122. However, when stearic acid is activated into stearyl-CoA, two high-energy phosphate bonds in one molecule of ATP are consumed, which is equivalent to the consumption of 2 molecules of ATP, so the net ATP generated by the oxidation of stearic acid β-oxidation is 122-2 = 120.
From this point of view, the oxidation of stearic acid β-oxidation provides energy to the body. This process is delicate and rigorous, and it is crucial for maintaining the energy requirements of life activities.
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