Tryptophan

L-Tryptophan

Names
IUPAC name Tryptophan or (2S)-2-amino-3-(1H-indol-3-yl)propanoic acid
Other names 2-Amino-3-(1H-indol-3-yl)propanoic acid
Identifiers
CAS Number	73-22-3 Y
3D model (Jmol)	Interactive image
ChEBI	CHEBI:27897 N
ChEMBL	ChEMBL54976 Y
ChemSpider	6066 Y
DrugBank	DB00150 Y
ECHA InfoCard	100.000.723
IUPHAR/BPS	717
KEGG	D00020 Y
PubChem	6305
UNII	8DUH1N11BX Y
InChI InChI=1S/C11H12N2O2/c12-9(11(14)15)5-7-6-13-10-4-2-1-3-8(7)10/h1-4,6,9,13H,5,12H2,(H,14,15)/t9-/m0/s1 Y Key: QIVBCDIJIAJPQS-VIFPVBQESA-N Y InChI=1/C11H12N2O2/c12-9(11(14)15)5-7-6-13-10-4-2-1-3-8(7)10/h1-4,6,9,13H,5,12H2,(H,14,15)/t9-/m0/s1 Key: QIVBCDIJIAJPQS-VIFPVBQEBP
SMILES c1ccc2c(c1)c(c[nH]2)C[C@@H](C(=O)O)N
Properties
Chemical formula	C11H12N2O2
Molar mass	204.23 g·mol−1
Solubility in water	Soluble: 0.23 g/L at 0 °C, 11.4 g/L at 25 °C, 17.1 g/L at 50 °C, 27.95 g/L at 75 °C
Solubility	Soluble in hot alcohol, alkali hydroxides; insoluble in chloroform.
Acidity (pKa)	2.38 (carboxyl), 9.39 (amino)
Magnetic susceptibility (χ)	-132.0·10−6 cm3/mol
Pharmacology
ATC code	N06AX02 (WHO)
Supplementary data page
Structure and properties	Refractive index (n), Dielectric constant (εr), etc.
Thermodynamic data	Phase behaviour solid–liquid–gas
Spectral data	UV, IR, NMR, MS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N  (what is YN ?)
Infobox references

11.4 g/L at 25 °C,
17.1 g/L at 50 °C,
27.95 g/L at 75 °C

Tryptophan (abbreviated as Trp or W; encoded by the codon UGG) is an α-amino acid that is used in the biosynthesis of proteins. It contains an α-amino group, an α-carboxylic acid group, and a side chain indole, classifying it as a non-polar, aromatic amino acid. It is essential in humans, meaning the body cannot synthesize it and thus it must be obtained from the diet. Tryptophan is also a precursor to the neurotransmitters serotonin and melatonin.

Like other amino acids, tryptophan is a zwitterion at physiological pH where the amino group is protonated (–NH₃⁺; pK_a = 9.39) and the carboxylic acid is deprotonated ( –COO⁻; pK_a = 2.38).

The isolation of tryptophan was first reported by Frederick Hopkins in 1901 through hydrolysis of casein. From 600 grams of crude casein one obtains 4-8 grams of tryptophan.

As an essential amino acid, tryptophan is not synthesized from more basic substances in humans and other animals, who must ingest tryptophan or tryptophan-containing proteins. Plants and microorganisms commonly synthesize tryptophan from shikimic acid or anthranilate by the following process: anthranilate condenses with phosphoribosylpyrophosphate (PRPP), generating pyrophosphate as a by-product. The ring of the ribose moiety is opened and subjected to reductive decarboxylation, producing indole-3-glycerinephosphate; this, in turn, is transformed into indole. In the last step, tryptophan synthase catalyzes the formation of tryptophan from indole and the amino acid serine.