Degradation of Pyrimidine Nucleotides
| A | NH3 | |
| B |
CO2 & H2O |
|
| C |
Both |
|
| D |
None |
What is the end product of catabolism of pyrimidine?
| A |
NH3 |
|
| B |
CO2 & H2O |
|
| C |
Both |
|
| D |
None |
The end products of pyrimidine catabolism are CO2 and H2O.
Pyrimidines are ultimately catabolized (degraded) to CO2, H2O, and urea. Cytosine can be broken down to uracil, which can be further broken down to N-carbamoyl-β-alanine, and then to beta-alanine, CO2, and ammonia by beta-ureidopropionase
Which is the product excreted unchanged in catabolism of pyrimidine?
| A |
Uric acid |
|
| B |
NH3 |
|
| C |
Pseudouridine |
|
| D |
Beta alanine |
No human enzyme catalyzes hydrolysis or phosphorolysis of the pseudouridine (ψ) derived from the degradation of RNA molecules.
This unusual nucleotide, therefore, is excreted unchanged in the urine of normal subjects.
Pseudouridine was indeed first isolated from human urine.
