Nucleotides- Salvage pathways Flashcards
Purine Bases: adenosine phosphoribosyl transferase catalyses the reaction of a free ??? with PRPP to get an adenine nucleotide
a free adenine
the deamination product of adenine is hypoxanthine which, in the salvage pathway for purines, is catalysed by hypoxanthine-guanine phosphoribosyltransferase to form ???
IMP
In the salvage pathway for purines, guanine is catalysed by hypoxanthine-guanine phosphoribosyltransferase to form ???
GMP
pyramidine bases salvage pathway exists in microorganisms and possibly in ???
mammals
in the pyramidine salvage pathway, thymidine phosphorylase catalyses thymine to ???
thymidine
Thymine is released from degraded ???
DNA
in the pyrimidine salvage pathway, thymidine kinase catalyses thymadine to ???
TMP
Pyrimidine salvage pathway: thymidine kinase catalyses= thymidine + ATP <–> ??? + ADP
TMP
purine salvage pathway: adenosine phosphoribosyl transferase catalyse: adenine + PRPP –> ??? + PPi
AMP
the anti-viral acyclovir is converted into a ??? inhibitor by viral (but not mammalian) thymidine kinase to terminate Viral DNA synthesis in herpes simplex infection
suicide inhibitor
Nucleoside monophosphates (AMP) can be converted to nucleoside ??? (ADP)
triphosphates
adenylate kinase phosphorylates AMP to ???
ADP
ADP is phosphorylated to ATP by glycolytic enzymes or through ??? phosphorylation
oxidative phosphorylation
nucleoside monophosphate kinases use ATP to form nucleoside ???
i.e ATP + NMP <–> ADP + NDP
diphosphates
nucleoside diphosphate kinases convert nucleoside diphosphates to ??? i.e NTP(D) + NDP(A) <–> NDP(D) + NTP(A)
triphosphates
purine degradation: produces ???
uric acid
impaired adenosine deaminase (ADA) increases ??? which leads to impaired T and B lymphocyte development = primary immune deficiency
dATP (used in DNA synthesis)
Defect in hypoxanthine and guanine salvage (pyrimidine salvage pathway) leads to ??? syndrome
lesch-nyhan
(Purine degradation) to reduce gout, allopurinol impairs ??? oxidase by lowering the uric acid
xanthine oxidase
adenosine deaminase deficiency leads to a 100x increase in ??? which is a strong inhibitor of ribonucleotide reductase = severe immunodeficiency disease
dATP
in severe immunnodeficiency disease, T & B lymphocytes don’t develop properly because of a deficiency in ???
adenosine deaminase
lesch-Nyhan syndrome is caused by a lack of hypoxanthine guanine phosphoribosyltransferase activity which causes an impairment of ??? and ??? salvage pathway synthesis
IMP and GMP
TRUE or FALSE: lesch-Nyhan syndrome: in the absence of HPRT, PRPP and purine synthesis increases, leasing to excess uric acid and tissue damage- but not of CNS especially.
FALSE
