|last1= Hertweck |first1= Christian |year= 2011 |title= Biosynthesis and Charging of Pyrrolysine, the 22nd Genetically Encoded Amino Acid |journal= Angew. Chem. Int. Ed. |volume= 50 |pages= 9540–9541 |doi= 10.1002/anie.201103769}}
</ref> koje se kombiniraju u peptidne lance ("polipeptide") za formiranje gradivnog bloka širokog spektra [[protein]]a.<ref name="NIGMS">{{cite web|url = http://publications.nigms.nih.gov/structlife/chapter1.html | title = The Structures of Life | publisher = National Institute of General Medical Sciences | accessdate = 20.</ref> Ovo su sve L-stereoizomeri ("ljevogirni" izomeri), a nekoliko D-stereoizomernih("desnogirnih") aminokiselina se javlja u [[bakterija|bakterijskom]] omotaču i nekim [[antibiotik|antibioticima]].<ref>"Biochemical pathways: an atlas of biochemistry and molecular biology" – Michal, p.5</ref> Dvadeset od proteinotvornih aminokiselina direktno kodiraju tripleti ([[kodon]]i) [[genetički kod|genetičkog koda]] i poznate su kao "standardne" aminokiseline. Ostale tri ("nestandardne" ili "ne-kanonske") su selenocistein (prisutan u mnogim ne-eukaryotima kao i u većini eukariota, ali nisu kodirane direktno sa [[DNK]]), [[pirolizin]] (nekih [[Archaea]] i jedne [[bakterija|bakterije]]) i N-formilmetionin (koji je često početna aminokiselina [[protein]]a u [[bakterija]]ma, [[mitohondrija|mitohondrijama]] i [[hloroplast]]ima). Pirolizin i selenocistein su kodirani preko varijantnih [[kodon]]a; selenocistein je kodiran STOP kodonom i SECIS elementom.<ref>[http://books.google.com/books?id=BDn AI_YBlMC&pg=PA1&lpg=PA1&ots=WSsFhHJwDy&sig=jkSLFr7AK8iu6OhdX7KOc10eKRY&hl=en&sa=X&ei=gshLUOWZLIin0AXRm4GoBg Modeling Electrostatic Contributions to Protein Folding and Binding] – Tjong, p.1 footnote</ref><ref>[http://books.google.com/books?id=VoJw6fIISSkC&pg=PA299&lpg=PA299&ots=C20L115r05&sig=4cix7yKNlod3xbzy2TWiOzEe6As&hl=en&sa=X&ei=H81LUL6MOfC10QX4wYG4Cw&ved=0CIcBEOgBMA8 Frontiers in Drug Design and Discovery] ed. Atta-Ur-Rahman & others, p.299</ref><ref name="url_The_Genetic_Codes_NCBI">{{cite web | url = http://www.ncbi.nlm.nih.gov/Taxonomy/Utils/wprintgc.cgi?mode=c | title = The Genetic Codes | author = Elzanowski A, Ostell J | authorlink = | date = 7 April 2008 | work = | publisher = National Center for Biotechnology Information (NCBI) | pages = | quote =</ref> Kombinacije kodona transfer [[RNK]] (tRNK) nisu nađene u prirodi što se također može koristiti za "proširenje" genetičkog koda i stvoriti mnoštvo proteina poznato kao aloproteini s aminokiselinama koje inače ne ulaze u sastav [[protein]]a.<ref name="pmid16260173">{{cite journal | author = Xie J, Schultz PG | title = Adding amino acids to the genetic repertoire | journal = Current Opinion in Chemical Biology | volume = 9 | issue = 6 | pages = 548–54 |date=December 2005 | pmid = 16260173 | doi = 10.1016/j.cbpa.2005.10.011 }}</ref><ref name="pmid19318213">{{cite journal | author = Wang Q, Parrish AR, Wang L | title = Expanding the genetic code for biological studies | journal = Chem. Biol. | volume = 16 | issue = 3 | pages = 323–36 |date=March 2009 | pmid = 19318213 | doi = 10.1016/j.chembiol.2009.03.001 | pmc = 2696486 }}</ref><ref name="isbn0-387-22046-1">{{cite book | author = Simon M | title = Emergent computation: emphasizing bioinformatics | publisher = AIP Press/Springer Science+Business Media | location = New York | year = 2005 | pages = 105–106 | isbn = 0-387-22046-1 }}</ref>
