Editing Nucleoside triphosphate (section)

=== Purine synthesis ===
A nitrogenous base called [[hypoxanthine]] is assembled directly onto PRPP.<ref>{{cite book| vauthors = Berg J, Tymoczko JL, Stryer L |date=2002 |title=Purine Bases Can Be Synthesized de Novo or Recycled by Salvage Pathways|url=https://www.ncbi.nlm.nih.gov/books/NBK22385/}}</ref> This results in a nucleotide called [[inosine monophosphate]] (IMP). IMP is then converted to either a precursor to AMP or GMP. Once AMP or GMP are formed, they can be phosphorylated by ATP to their diphosphate and triphosphate forms.<ref>{{Cite news|url=http://www.biochemden.com/purine-synthesis/|title=Purine Synthesis : Synthesis of Purine RiboNucleotides|date=2016-03-16|work=BiochemDen.com|access-date= 15 November 2017 }}</ref>

Purine synthesis is regulated by the [[Allosteric regulation|allosteric inhibition]] of IMP formation by the adenine or guanine nucleotides.<ref>{{cite book | vauthors = Berg JM, Tymoczko JL, Stryer L |date=2002|title=Key Steps in Nucleotide Biosynthesis Are Regulated by Feedback Inhibition|url=https://www.ncbi.nlm.nih.gov/books/NBK22428/}}</ref> AMP and GMP also [[Competitive inhibition|competitively inhibit]] the formation of their precursors from IMP.<ref name="Nierlich_1965">{{cite journal | vauthors = Nierlich DP, Magasanik B | title = Regulation of purine ribonucleotide synthesis by end product inhibition. the effect of adenine and guanine ribonucleotides on the 5'-phosphoribosyl-pyrophosphate amidotransferase of aerobacter aerogenes | journal = The Journal of Biological Chemistry | volume = 240 | pages = 358–65 | year = 1965 | doi = 10.1016/S0021-9258(18)97657-X | pmid = 14253438 | doi-access = free }}</ref>