How much ATP energy would you get from a tripeptide that, upon hydrolysis and deamination, makes two acetyl CoA and one pyruvate molecule and undergo aerobic respiration?
To determine the amount of ATP energy produced from a tripeptide through aerobic respiration, we can calculate the total ATP yield from the products of its breakdown.
First, let's break down the steps involved:
1. The tripeptide is hydrolyzed into its individual amino acids.
2. Each amino acid undergoes deamination, resulting in the release of ammonia (NH3) and a keto acid.
3. The keto acids are further converted into acetyl CoA or pyruvate, which then enter the citric acid cycle (also known as the Krebs cycle) for aerobic respiration.
Now, let's focus on the specific breakdown of the tripeptide mentioned in the question, which yields two acetyl CoA molecules and one pyruvate molecule.
1. Each amino acid in the tripeptide results in one pyruvate molecule after deamination and conversion.
- Since there are three amino acids in the tripeptide, we end up with three pyruvate molecules.
2. For each pyruvate molecule, in aerobic respiration, it will be further converted into acetyl CoA before entering the citric acid cycle.
- However, it is important to note that the process of converting pyruvate to acetyl CoA requires the use of two molecules of NAD+ (nicotinamide adenine dinucleotide) to produce two molecules of NADH (reduced form of NAD+). This process occurs through the pyruvate dehydrogenase complex.
Now, let's calculate the ATP yield from the two acetyl CoA molecules and the three pyruvate molecules:
1. Each acetyl CoA molecule entering the citric acid cycle can generate approximately 12 ATP molecules (through oxidative phosphorylation).
- Therefore, two acetyl CoA molecules would generate a total of 2 x 12 = 24 ATP molecules.
2. Each pyruvate molecule will generate a certain amount of ATP molecules during the citric acid cycle, depending on the complete oxidation of acetyl CoA produced from it.
- On average, from one complete oxidation of acetyl CoA, approximately 10 ATP molecules are produced through oxidative phosphorylation.
- Therefore, three pyruvate molecules would generate a total of 3 x 10 = 30 ATP molecules.
Summing up the ATP yields from the acetyl CoA and pyruvate metabolism, we have:
Acetyl CoA: 24 ATP
Pyruvate: 30 ATP
Thus, the total ATP energy yield from the given tripeptide, upon hydrolysis and deamination, leading to the production of two acetyl CoA and one pyruvate molecule, and undergoing aerobic respiration, would be 24 ATP (from acetyl CoA) + 30 ATP (from pyruvate) = 54 ATP.