Lecture 14 - Pyrimidine Synthesis Flashcards
Where does each atom of a pyrimidine come from?
- N-C from carbamoyl phosphate
- C-C-C-N from aspartate
What is the major difference between the pyrimidine and purine pathways?
The pyrimidine ring is built independently and then added to the ribose by a phosphoribosyl transferase
Step 1 of UMP synthesis
Glutamine + CO2 + 2 ATP -> carbamoyl phosphate
Enzyme of step 1 of UMP synthesis
Carbamoyl phosphate synthetase
Cofactor of step 1 of UMP synthesis
Glutamate + 2 ADP + Pi out
Where does step 1 of UMP synthesis occur?
Cytoplasm
Step 2 of UMP synthesis
Carbamoyl phosphate + aspartate -> N-carbamoylaspartate
Enzyme of step 2 of UMP synthesis
Aspartate transcarbamoylase
Cofactor of step 2 of UMP synthesis
Pi out
Step 3 of UMP synthesis
N-carbamoylaspartate ->dihydroorotate
Enzyme of step 3 of UMP synthesis
Dihydroorotase
Cofactor of step 3 of UMP synthesis
H2O out
Step 4 of UMP synthesis
Dihydroorotate -> orotate
Enzyme of step 4 of UMP synthesis
Dihydroorotate dehydrogenase
Cofactor of step 4 of UMP synthesis
FAD -> FADH2
Step 5 of UMP synthesis
Orotate -> orotidine monophosphate
Enzyme of step 5 of UMP synthesis
Orotate phosphoribosyl transferase
Cofactor of step 5 of UMP synthesis
PRPP -> PPi
Step 6 of UMP synthesis
Orotidine monophosphate -> uridine monophosphate
Enzyme of step 6 of UMP synthesis
Orotidine monophosphate decarboxylase
Cofactor of step 6 of UMP synthesis
CO2 out
Which type of enzyme adds phosphate groups?
Kinase
Which type of enzyme removes phosphate groups?
Pyrophosphate
What is the cofactor needed for kinase enzymes?
ATP -> ADP
