Editing Methionine (section)

==Biochemical details==
Methionine (abbreviated as '''Met''' or '''M'''; encoded by the codon AUG) is an α-[[amino acid]] that is used in the [[biosynthesis]] of [[protein]]s. It contains a [[carboxyl group]] (which is in the deprotonated −COO<sup>−</sup> form under biological [[pH]] conditions), an [[amino group]] (which is in the [[protonated]] {{chem|−NH|3|+}} form under biological pH conditions) located in α-position with respect to the carboxyl group, and an ''S''-methyl [[thioether]] side chain, classifying it as a [[Chemical polarity|nonpolar]], [[Aliphatic compound|aliphatic]] amino acid.{{cn|date=October 2024}}

In nuclear genes of [[eukaryote]]s and in [[Archaea]], methionine is coded for by the [[start codon]], meaning it indicates the start of the [[coding region]] and is the first amino acid produced in a nascent [[Peptide|polypeptide]] during [[mRNA]] [[Translation (biology)|translation]].<ref>{{Cite journal |vauthors=Guedes RL, Prosdocimi F, Fernandes GR, Moura LK, Ribeiro HA, Ortega JM |date=December 2011 |title=Amino acids biosynthesis and nitrogen assimilation pathways: a great genomic deletion during eukaryotes evolution |journal=BMC Genomics |volume=12 |issue=Suppl 4 |pages=S2 |doi=10.1186/1471-2164-12-S4-S2 |pmc=3287585 |pmid=22369087 |doi-access=free }}</ref>