12: Nucleotide Metabolism Flashcards
Nucletide
the nucleoside plus the phosphate groups
Where does the ribose in a nucleotide come from?
pentose phosphate pathway
Purines have __ ring(s)
2
Pyrimidines have __ ring(s)
1
Where do the amines come from in a purine?
aspartate and glutamine
Folate
Vitamin B9 contributes to purines
PRPP
phosphoribosyl pyrophosphate (activated form of ribose)
How are the salvage and de novo pathways regulated?
feedback inhibition
Salvage pathway of purine synthesis
guanine and adenine are synthesized from hypoxanthine
What is guanine converted to in the salvage pathway?
GMP
What is adenine converted to in the salvage pathway?
AMP
What is a common precursor for GMP and AMP synthesis?
IMP
What is used to make ATP in the de novo pathway?
GTP
What is used to make ATP in the de novo pathway?
ATP
De novo purine nucleotide synthesis
base needs to be built first
T/F: Purines can quickly convert from one nucleotide to another
T
Pyrimidine de novo synthesis
build the base and then attach it to PRPP
What does uridine monophosphate synthase do?
makes uridine to uracil which is added to PRPP
DUMPS
deficiency of uridine monophosphate synthase
What does uridine monophosphate synthase do?
performs last 2 steps of UMP formation
What is increased in serum for animals with DUMPS?
orotic acid
What enzyme is used to synthesize deoxyribonucleotides?
ribonucleotide reductase
What type of reaction is the synthesis of deoxyribonucleotides?
redox
What intermediate is needed for the synthesis of deoxyribonucleotides?
NADPH
What must uracil be converted to for the synthesis of deoxyribonucleotides?
thymidine
What enzyme produces uric acid?
xanthine oxidase
What inhibits purines forming urate?
allopurinol
What is uric acid from purine breakdown in non-primate mammals excreted as?
allantoin
