Lippincott - Nucleotide Metabolism Flashcards
composition of nucleoside
pentose sugar + base
composition of nucleotide
nucleoside + 1 or more phosphate groups
deoxyribose sugars are formed by removing the oxygen associated with which carbon of a ribose sugar?
2nd carbon
nitrogens of purine rings come from:
[1] glycine
[2] glutamine
[3] aspartate
carbons of purine rings come from:
[1] glycine
[2] carbon dioxide
[3] N-formyl-tetrahydrofolate
organ where purine rings are synthesized
liver
activated pentose that is a major part of purine and pyrimidine biosynthesis
PRPP
committed step in de novo synthesis of purines
synthesis of 5’ phosphoribosylamine from PRPP and glutamine
parent purine nucleotide
inosine monophosphate
energy requirement for conversion of IMP to GMP
ATP
energy requirement for conversion of IMP to AMP
GTP
responsible for synthesis of nucleoside diphosphates
base specific nucleoside monophosphate kinase (adenylate kinase, guanylate kinase, etc)
responsible for synthesis of nucleoside triphosphates
nonspecific nucleoside diphosphate kinase
enzymes involved in salvage pathway for purines
[1] adenine phosphoribosyltransferase (APRT)
[2] hypoxanthine-guanine phosphoribosyltransferase (HGPRT)
salvage pathway for purines - hypoxanthine is converted to:
IMP
salvage pathway for purines - guanine is converted to:
GMP
salvage pathway for purines - adenine is converted to
AMP
Lesch-Nyhan syndrome
x linked recessive disorder associated with complete deficiency of HGPRT –> inability to salvage hypoxanthine or guanine –> high uric acid due to excessive degradation
responsible for deoxyribonucleotide synthesis from ribonucleotides
ribonucleotide reductase
inhibitor of ribonucleotide reductase
dATP binding to allosteric sites
organ of degradation of purine nucleotides
liver
end product of purine degradation
uric acid
hydrolyze dietary DNA
deoxyribonucleases
hydrolyze dietary RNA
ribonucleases
product of DNA/RNA hydrolysis
oligonucleotides
hydrolyze oligonucleotides
pancreatic phosphodiesterases
responsible for removing phosphate groups from nucleotides
nucleotidases
carbons of pyrimidine come from;
[1] aspartic acid
[2] carbon dioxide
nitrogens of pyrimidine come from:
[1] R group of glutamine
[2] aspartic acid
regulated step in de novo pyrimidine synthesis
synthesis of carbamoyl phosphate from glutamine and carbon dioxide
catalyzes regulated step in de novo pyrimidine synthesis
carbamoyl phosphate synthetase II
inhibit CPS II
UTP
activate CPS II
PRPP
difference of CPS I and CPS II
CPS I is used in the urea cycle, CPS II is used in de novo pyrimidine synthesis
main enzymes in orotic acid synthesis
CAD
[1] CPS II
[2] aspartate transcarbamolyase
[3] dihydroorotase
major intermediate in de novo pyrimidine synthesis
UMP
how is CTP synthesized from UTP?
amination of UTP by CTP synthetase
responsible for CTP synthesis from UTP
CTP synthetase
responsible for TMP synthesis from dUMP
thymidylate synthase
source of the methyl group in TMP synthesis
N5N10 methylene tetrahydrofolate
end products of pyrimidine degradation
[1] beta alanine
[2] beta aminoisobutyrate
[3] NH3
[4] CO2
[T/F] pyrimidines are more frequently salvaged in human cells compared to purines
F
