Moizy 1 Flashcards
T or F. In purine synthesis, donated atoms are added to a preformed ribose 5 phosphate.
True.
Atoms of a purine ring are donated by which 3 amino acids?
aspartic acid, glutamine, glycine.
Ribose 5 phosphate to PRPP.
PRPP synthetase
PRPP synthetase is inhibited by
free floating phosphate
purines (end product inhibition)
What is the committed step of purine synthesis?
PRPP to 5’ phosphoribosylamine.
5’ phosphoribosylamine to inosine 5 monophosphate (IMP) costs how much ATP?
4
What do sulfonamides do?
Block IMP production by inhibiting folic acid synthesis. No folic acid, no tetrahydrofolate (THF) cofactor for purine synthesis.
T or F. Because sulfonamides inhibit folic acid synthesis, humans are affected by sulfonamides.
False. Humans cannot synthesize folic acid.
What does methotrexate do?
Analog of folic acid, decreases reduction of dihydrofolate (DHF) to THF.
Synthesis of IMP to AMP requires _____.
Synthesis of IMP to GMP requires ______.
GTP
ATP.
IMP to GMP. enzyme?
IMP dehydrogenase.
What does mycophenolic acid (MPA) do?
blocks IMP dehydrogenase, blocks GMP production depriving rapidly proliferating T and B cells of nucleic acids, decreasing graft rejection.
AMP to ADP
GMP to GDP
base specific nucleoside monophosphate kinases.
adenylate kinase
guanylate kinase
T or F. Nucleoside diphosphate kinases are base specific, similar to nucleoside monophosphate kinases.
False. Broad specificity.
Pyrimidines are made ______ being attached to ribose 5 phosphate.
before
Which amino acids donate atoms to pyrimidines?
aspartic acid, glutamine (no glycine like purines).
In pyrimidine synthesis, Glutamine –> ___________ using what enzyme? Is ATP used or produced, and how many?
carbomoyl phosphate using carbomoyl phosphate synthetase.
2 ATP used.