Tyrosine

L-Tyrosine or tyrosine (symbol Tyr or Y) or 4-hydroxyphenylalanine is one of the 20 standard amino acids that are used by cells to synthesize proteins. It is a conditionally essential amino acid with a polar side group. The word "tyrosine" is from the Greek tyrós, meaning cheese, as it was first discovered in 1846 by German chemist Justus von Liebig in the protein casein from cheese. It is called tyrosyl when referred to as a functional group or side chain. While tyrosine is generally classified as a hydrophobic amino acid, it is more hydrophilic than phenylalanine. It is encoded by the codons UAC and UAU in messenger RNA.

Tyrosine

Skeletal formula of L-tyrosine
L-Tyrosine at physiological pH
ball-and-stick model space-filling model
Names
IUPAC name (S)-Tyrosine
Other names L-2-Amino-3-(4-hydroxyphenyl)propanoic acid
Identifiers
CAS Number	60-18-4 (L) Y
3D model (JSmol)	Interactive image Zwitterion: Interactive image
ChEBI	CHEBI:17895 Y
ChEMBL	ChEMBL925 Y
ChemSpider	5833 Y
DrugBank	DB00135 Y
ECHA InfoCard	100.000.419
IUPHAR/BPS	4791
KEGG	C00082
PubChem CID	6057
UNII	42HK56048U Y
CompTox Dashboard (EPA)	DTXSID1023730
InChI InChI=1S/C9H11NO3/c10-8(9(12)13)5-6-1-3-7(11)4-2-6/h1-4,8,11H,5,10H2,(H,12,13)/t8-/m0/s1 Y Key: OUYCCCASQSFEME-QMMMGPOBSA-N Y Key: OUYCCCASQSFEME-UHFFFAOYSA-N Key: OUYCCCASQSFEME-MRVPVSSYSA-N
SMILES N[C@@H](Cc1ccc(O)cc1)C(O)=O Zwitterion: [NH3+][C@@H](Cc1ccc(O)cc1)C([O-])=O
Properties
Chemical formula	C9H11NO3
Molar mass	181.191 g·mol−1
Appearance	white solid
Solubility in water	.0453 g/100 mL
Magnetic susceptibility (χ)	-105.3·10−6 cm3/mol
Hazards
NFPA 704 (fire diamond)	1 1 0
Supplementary data page
Tyrosine (data page)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

The one-letter symbol Y was assigned to tyrosine for being alphabetically nearest of those letters available. Note that T was assigned to the structurally simpler threonine, U was avoided for its similarity with V for valine, W was assigned to tryptophan, while X was reserved for undetermined or atypical amino acids. The mnemonic tYrosine was also proposed.