L18 Flashcards
Tyrosine is a precursor for which 3 hormones?
Dopamine, norepinephrine, and epinephrine
Glutamate is a precursor for which hormone?
GABA
Histidine is a precursor for which hormone?
Histamine
Tryptophan is a precursor for which hormone?
Serotonin
By which mechanism do amino acids convert into hormones?
Decarboxylation and hydroxylation
Galantamine is an alkaloid synthesized from which aa precursors? In which plant is it made?
Phe and Tyr. Daffodails
Morphine is an alkaloid synthesized from which aa precursors? In which plant is it made?
Two Tyr. Poppies
Cofactors for NT
Flavins, NADPH, NADH, and CoA
Is NT breakdown a significant source of energy?
NO
Difference between NT and nucleoside?
NT = pentose sugar + base + phosphate Nucleoside = pentose sugar + base
Which NT are the purines? How many rings?
A and G. 2 rings
Which NT are the pyrimidines? How many rings?
T, C, and U. 1 ring
Which are the main 3 aa involved in NT synthesis?
Asp, Gln, and Gly
Which is the main reactant for NT synthesis?
Ribose 5-P
Purines can be degraded into what?
Uric acid and ribose 1-P
Pyrimidines can be degraded into what?
Ribose 1-P and malonyl-CoA
What is the general pathway for making purines?
Pentose phosphate pathway -> ribose 5-P + ATP -> Phosphoribosylpyrophosphate (PRPP) -> IMP -> AMP and GMP
What is the general pathway for making pyrimidines?
Pentose phosphate pathway -> ribose 5-P + ATP -> Phosphoribosylpyrophosphate (PRPP) -> Asp + carbamoyl-P -> UTP -> CTP
Overall, from what are purines made?
2 formate, CO2, Gly, Asp, and Gln
How is purine synthesis regulated?
Allosterically by ADP, AMP, GMP, and IMP
How are NT monophosphates converted to NT triphosphates?
NT monophosphate kinases -> adenylate kinase -> guanylate kinase -> NT di-P kinase
Which enzyme should be inhibited to prevent both purine and pyrimidine synthesis? What does it do?
PRPP synthetase, which normally converts ribose 5-P into PRPP
Which enzyme should be inhibited to prevent purine synthesis but allow pyrimidine synthesis? What does it do?
Glutamine-PRPP amidotransferase, which normally converts PRPP into 5-Phosphoribosylamine
Overall, from what are pyrimidines made? Ordering of synthesis?
Gln, Asp, and CO2. Pyrimidine ring formed first and then linked to PRPP
How is pyrimidine synthesis regulated?
CTP end product inhibition
CPSII inhibited by UTP, activated by ATP and PRPP
OPR transferase stimulated by ATP
Overall, pyrimidines inhibit pathway and purines stimulate it
Describe the purine salvage/catabolism pathway
Salvage: GMP and AMP convert into guanine and hypoxanthine and react with PRPP through transferase to form GMP + PPi and IMP + PPi
Catabolism: uric acid
Describe the catabolism of pyrimidines
Broken down into urea via carbamoyl-P, malonyl-CoA , and CO2
How does RNA convert to DNA?
Deoxy through ribonucleotide reductase. It uses NADPH as the electron donor. FAD is an electron acceptor/donor. NDP -> dNDP + water after reaction. Four subunits.
How is ribonucleotide reductase regulated?
By many NT in order to balance ribo-NT vs deoxyribo-NT in body
How is thymine made?
dUMP -> dTMP by folate thymidylate synthetase
Which NT is targeted for chemotherapy and why? How is it targeted?
Thymine because cancer cells can’t make DNA without it! Target dihydrofolate reductase
