PRPP glutamyl amidotransferase is increased to increase purine synthesis in ?
PRPP glutamyl amidotransferase is one of the rate limiting enzyme in de novo synthesis of purines. o The de novo synthesis of purines is most active in liver. Brain, RBCs (erythrocytes) and polymorphonuclear leokocytes (polymorphs) cannot synthesize purine nucleotides by de novo pathway. Biosynthesis of purine neucleotides Two impoant purine nucleotides are synthesized : (i) adenosine monophosphate (AMP) and (ii) guanosine monophosphate (GMP). Then AMP and GMP are conveed to other purine nucleotides like ADP, ATP, GDP, GTP etc. Purine nucleotides can be synthesized by two pathways - (I) De novo synthesis and (2) Salvage pathway. De novo pathway (De novo synthesis) In de novo pathway, the purine nucleotides are synthesized from amphibolic intermediates. Amphibolic intermediates are the intermediary metabolites of amphibolic pathways (eg. citric acid cycle) which have dual purposes, i e. they serve in catabolism as well as in anabolism. In de novo synthesis, purine ring is formed from variety of precursors is assembled on ribose-5-phosphate. Precursors for de novo synthesis are ? i) Glycine provides C4 C5 and N7 ii) Aspaate provides NI iii) Glutamine provides N3 and N9 iv) Tetrahydrofolate derivatives furnish C2 and Cs v) Carbon dioxide provides C6
Liver
RBC
Brain
Polymorphs