Editing Metabolism (section)

===Nucleotide synthesis and salvage===
{{further|Nucleotide salvage|Pyrimidine biosynthesis|Purine#Metabolism}}
Nucleotides are made from amino acids, carbon dioxide and [[formic acid]] in pathways that require large amounts of metabolic energy.<ref name="Rudolph-1994">{{cite journal | vauthors = Rudolph FB | title = The biochemistry and physiology of nucleotides | journal = The Journal of Nutrition | volume = 124 | issue = 1 Suppl | pages = 124S–127S | date = January 1994 | pmid = 8283301 | doi = 10.1093/jn/124.suppl_1.124S | doi-access = free }} {{cite journal | vauthors = Zrenner R, Stitt M, Sonnewald U, Boldt R | title = Pyrimidine and purine biosynthesis and degradation in plants | journal = [[Annual Review of Plant Biology]] | volume = 57 | pages = 805–36 | year = 2006 | issue = 1 | pmid = 16669783 | doi = 10.1146/annurev.arplant.57.032905.105421 | bibcode = 2006AnRPB..57..805Z }}</ref> Consequently, most organisms have efficient systems to salvage preformed nucleotides.<ref name="Rudolph-1994"/><ref>{{cite journal | vauthors = Stasolla C, Katahira R, Thorpe TA, Ashihara H | title = Purine and pyrimidine nucleotide metabolism in higher plants | journal = Journal of Plant Physiology | volume = 160 | issue = 11 | pages = 1271–95 | date = November 2003 | pmid = 14658380 | doi = 10.1078/0176-1617-01169 | bibcode = 2003JPPhy.160.1271S }}</ref> [[Purine]]s are synthesized as [[nucleoside]]s (bases attached to [[ribose]]).<ref name="Davies-2012">{{cite journal | vauthors = Davies O, Mendes P, Smallbone K, Malys N | title = Characterisation of multiple substrate-specific (d)ITP/(d)XTPase and modelling of deaminated purine nucleotide metabolism | journal = BMB Reports | volume = 45 | issue = 4 | pages = 259–64 | date = April 2012 | pmid = 22531138 | doi = 10.5483/BMBRep.2012.45.4.259 | url = http://wrap.warwick.ac.uk/49510/1/WRAP_Malys_%5B45-4%5D1204261917_%28259-264%29BMB_11-169.pdf | doi-access = free | access-date = 18 September 2019 | archive-date = 24 October 2020 | archive-url = https://web.archive.org/web/20201024132423/http://wrap.warwick.ac.uk/49510/1/WRAP_Malys_%5B45-4%5D1204261917_%28259-264%29BMB_11-169.pdf | url-status = live }}</ref> Both [[adenine]] and [[guanine]] are made from the precursor nucleoside [[inosine]] monophosphate, which is synthesized using atoms from the amino acids [[glycine]], [[glutamine]], and [[aspartic acid]], as well as [[formate]] transferred from the [[coenzyme]] [[folic acid|tetrahydrofolate]]. [[Pyrimidine]]s, on the other hand, are synthesized from the base [[Pyrimidinecarboxylic acid|orotate]], which is formed from glutamine and aspartate.<ref>{{cite journal | vauthors = Smith JL | title = Enzymes of nucleotide synthesis | journal = Current Opinion in Structural Biology | volume = 5 | issue = 6 | pages = 752–7 | date = December 1995 | pmid = 8749362 | doi = 10.1016/0959-440X(95)80007-7 }}</ref>