Verwarring tussen het aantal bestaande amino zuren

[Yami-no Leafion]

Hallo,

Ik had een vraag over hoeveel aminozuren er nu eigenlijk zijn. Ik heb geleerd dat er 22 aminozuren zijn (waarvan 9 essentieel en 13 niet essentieel). Nu lees ik in een boek over imunologie dat er maar 20 soorten aminozuren zijn.

Als ik op het internet kijk zie ik de ene keer 20 soorten en de andere keer 22 soorten. Hoe kan dat?

[ArcherBarry]

In verband met tijd gebrek citeer ik even een bron.

There are approximately 20,000 unique protein encoding genes responsible for more than 100,000 unique proteins in the human body. Although there are hundreds of amino acids found in nature, only about 20 amino acids are needed to make all the proteins found in the human body and most other forms of life. These 20 amino acids are all L-isomer, alpha-amino acids. All of them, except for glycine, contain a chiral alpha carbon. And all these amino acids are L-isomers with an R-absolute configuration except for glycine (no chiral center) and cysteine (S-absolute configuration, because of the sulfur-containing R-group). It bears mentioning that the amino acids selenocysteine and pyrrolysine are considered the 21st and 22nd amino acids, respectively. They are more recently discovered amino acids that may become incorporated into protein chains during ribosomal protein synthesis. Pyrroloysine has functionality in life; however, humans do not use pyrrolysine in protein synthesis. Once translated, these 22 amino acids may also be modified via a post-translational modification to add further diversity in generating proteins.[8]

overzicht bron
originele bron: Wu G. Amino acids: metabolism, functions, and nutrition. Amino Acids. 2009 May;37(1):1-17.