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Tryptophan

L-Tryptophan
Structure of L-isomer
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
73-22-3 YesY
3D model (Jmol) Interactive image
ChEBI CHEBI:27897 N
ChEMBL ChEMBL54976 YesY
ChemSpider 6066 YesY
DrugBank DB00150 YesY
ECHA InfoCard 100.000.723
717
KEGG D00020 YesY
PubChem 6305
UNII 8DUH1N11BX YesY
Properties
C11H12N2O2
Molar mass 204.23 g·mol−1
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)
-132.0·10−6 cm3/mol
Pharmacology
N06AX02 (WHO)
Supplementary data page
Refractive index (n),
Dielectric constantr), etc.
Thermodynamic
data
Phase behaviour
solid–liquid–gas
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 YesYN ?)
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+; pKa = 9.39) and the carboxylic acid is deprotonated ( –COO; pKa = 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.


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