Question 24.11: Identify the citric acid cycle intermediate produced by each...
Identify the citric acid cycle intermediate produced by each of the following amino acids. Determine the number of ATP that can be produced when that intermediate proceeds through the remaining steps of the citric acid cycle and the resulting coenzymes are oxidized in electron transport:
a. proline b. tyrosine c. tryptophan
a. Proline is converted to the citric acid cycle intermediate α-ketoglutarate. The reactions in the remaining part of the citric acid cycle from α-ketoglutarate to oxaloacetate produce two NADH, one GTP, and one FADH_{2}. The oxidation of two NADH provides energy to synthesize five ATP, one GTP provides one ATP, and the oxidation of one FADH_{2} provides energy to synthesize 1.5 ATP, for a total of 7.5 ATP from proline.
b. Tyrosine is converted to the citric acid cycle intermediate fumarate. The remaining reactions of the citric acid cycle from fumarate to oxaloacetate produce one NADH, which can be oxidized via electron transport to provide the energy to synthesize 2.5 ATP.
c. Tryptophan is converted to the citric acid cycle intermediate acetyl CoA. The reactions in the citric acid cycle starting with acetyl CoA produce three NADH, one GTP, and one FADH_{2}. The oxidation of three NADH provides energy to synthesize 7.5 ATP, one GTP provides one ATP, and the oxidation of one FADH_{2} provides the energy to synthesize 1.5 ATP, for a total of 10 ATP from tryptophan.
| ANALYZE THE PROBLEM | Given | Need | Connect |
| proline, tyrosine, tryptophan | ATP produced via the citric acid cycle and electron transport | NADH, FADH_{2}, GTP |