Flashcards in Lecture 21 - Nucleotide Metabolism Deck (23):
The committed step of purine synthesis is _____.
PRPP to phsophoribosylamine (activated by the addition of C1 amine group)
Closes the nitrogenous base in purine synthesis
tetrahydrofolate (specifically, N5-formyl THF)
Reduces NDPs to dNDPs
Inosinate is the intermediate in ___ and ___ production.
dATP and dGTP production
Between __ and ___, the N-base rings are built in purine synthesis.
Closes the purine ring structure
Feedback inhibition of purine synthesis:
PRPP and PR-amine is inhibited by _____
Step 1 of de novo purine synthesis occurs when ______ catabolizes ribose-5-phosphate to phosphoribosyl pyrophosphate
Why is purine salvage an important biochemical process?
Pyrimidine triphosphates are important energy carriers (ATP; GTP), so they are salvaged to "run" other processes.
Purine salvage involves the loss of ____ from ribose to attach the nitrogenous base.
C1 Pi (the inorganic phosphate from Carbon 1)
Catalyst for AMP salvage
adenine phosphoribosyl-transferase (APRT)
Catalyst for guanine salvage
Hypoxanthine-guanine phosphoribosyl-transferas (HGPRT)
Pyrimidines are salvaged by ______.
Phosphoribosyl-5-pyrophosphate (PRPP) is important as it is critical in the production of _______ ______.
A. ATP molecules
B. GTP molecules
C. FAD molecules
D. Purine nucleotides
D. purine nucleotides (A & G)
GTP and ATP production use what for energy?
ATP for GTP production
GTP for ATP production
IMP production is inhibited by _____.
GMP production is stimulated by _____.
ATP (ATP needs more GMP to bind to)
AMP production is stimulated by _____.
GMP (GMP needs more ATP to bind to)
What is produced first in pyrimidine synthesis?
Carbamoyl phosphate (made by carbamoyl phosphate synthase II)
Carbamoyl phosphate is transformed into carbamoyl-aspartate by _________.
Dihydroorotate is changed to orotate in the _____.
Orotate and ____ join to begin the final pyrimidine structure.