Salvage purine synthesis refers to ?

Ans. is 'c' i.e., Synthesis of purine nucleotides from purine bases 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 - (1) 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 ? Glycine provides Ca, C5 and N7 Aspaate provides N, Glutamine provides N3 and N9 Tetrahydrofolate derivatives furnish C2 and C8 Carbon dioxide provides Co Salvage pathway of purine nucleotide synthesis Free purine bases (adenine, guanine and hypoxanthine) and purine nucleosides are formed in cells during the metabolic degradation of nucleic acids and nucleotides. These free purine bases and purine nucleosides are reused in the formation of purine nucleotides. This is called salvage pathway (salvage means propey saved from loss). Salvage synthesis requires far less energy than de novo synthesis.