Alex project. Online Scientific Calculator and Math Help. Photo : yfrog.com/h641598189j - Shared by A1eksanderr. Journal of Zoology - Journal Information. German. History. Amino acid. The generic structure of an alpha amino acid in its un-ionized form Many important proteinogenic and non-proteinogenic amino acids also play critical non-protein roles within the body.
For example, in the human brain, glutamate (standard glutamic acid) and gamma-amino-butyric acid ("GABA", non-standard gamma-amino acid) are, respectively, the main excitatory and inhibitory neurotransmitters;[18] hydroxyproline (a major component of the connective tissue collagen) is synthesised from proline; the standard amino acid glycine is used to synthesise porphyrins used in red blood cells; and the non-standard carnitine is used in lipid transport. Nine proteinogenic amino acids are called "essential" for humans because they cannot be created from other compounds by the human body and, so, must be taken in as food.