Names | |
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IUPAC name
Tryptophan or (2S)-2-amino-3-(1H-indol-3-yl)propanoic acid
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Other names
2-Amino-3-(1H-indol-3-yl)propanoic acid
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Identifiers | |
3D model (JSmol)
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ChEBI | |
ChemSpider | |
DrugBank | |
ECHA InfoCard | 100.000.723 |
KEGG | |
PubChem CID
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UNII | |
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Properties | |
C11H12N2O2 | |
Molar mass | 204.23 g·mol−1 |
Soluble: 0.23 g/L at 0 °C, 11.4 g/L at 25 °C, |
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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 constant (εr), etc. |
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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).
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what is ?) | (|
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 neurotransmitter serotonin and the hormone 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.