Title: Tryptophan
CAS Registry Number: 73-22-3
CAS Name: L-Tryptophan
Additional Names: Trp; W; (S)-a-amino-1H-indole-3-propanoic acid; l-a-aminoindole-3-propionic acid; l-a-amino-3-indolepropionic acid; 2-amino-3-indolylpropanoic acid; l-b-3-indolylalanine
Trademarks: Ardeytropin (Ardeypharm); Kalma (Fresenius); Optimax (Merck KGaA); Pacitron (Rorer); Sedanoct (Woelm); Trofan (Upsher-Smith); Tryptan (Valeant)
Molecular Formula: C11H12N2O2
Molecular Weight: 204.23
Percent Composition: C 64.69%, H 5.92%, N 13.72%, O 15.67%
Literature References: An essential amino acid for human development; precursor of serotonin, q.v. Isoln from casein: F. G. Hopkins, S. W. Cole, J. Physiol. 27, 418 (1902). Structure: A. Ellinger, Ber. 39, 2515 (1906); A. Ellinger, A. C. Flamand, Ber. 40, 3029 (1907). Early chemistry and biochemistry: Amino Acids and Proteins, D. M. Greenberg, Ed. (Charles C. Thomas, Springfield, IL, 1951) 950 pp., passim; J. P. Greenstein, M. Winitz, Chemistry of the Amino Acids vols 1-3 (John Wiley and Sons, Inc., New York, 1961) pp. 2316-2347, passim. Intrinsic fluorescent/phosphorescent moiety in proteins; used in characterizing structure and conformational changes: E. A. Burstein et al., Photochem. Photobiol. 18, 263 (1973); C. Pokalsky et al., J. Biol. Chem. 270, 3809 (1995); review of phosphorescence: S. Papp, J. M. Vanderkooi, Photochem. Photobiol. 49, 775-784 (1989). Review of microbial production: T. K. Maiti, S. P. Chatterjee, Hind. Antibiot. Bull. 33, 26-61 (1991). Review of biosynthesis: I. P. Crawford, G. V. Stauffer, Annu. Rev. Biochem. 49, 163-195 (1980); of nutrition and metabolism: J. C. Peters. Adv. Exp. Med. Biol. 294, 345-358 (1991). Review of use in depression: S. N. Young, J. Psychiatr. Neurosci. 16, 241-246 (1991); in neuropsychiatric disorders: R. Sandyk, Int. J. Neurosci. 67, 127-144 (1992). Review as toxic agent in eosinophilia-myalgia syndrome (EMS): D. S. Milburn, C. W. Myers, DICP Ann. Pharmacother. 25, 1259 (1991); L. D. Kaufman, R. M. Philen, Drug Saf. 8, 89-98 (1993).
Properties: Leaflets or plates from dil alc, dec 289° (rapid heating). [a]D23 -31.5° (c = 1); [a]D20 +2.4° (0.5N HCl); [a]D20 +0.15° (c = 2.43 in 0.5N NaOH). pK1 2.38; pK2 9.39. Soly in water (g/l): 8.23 at 0°; 10.57 at 20°; 11.36 at 25°; 17.06 at 50°; 27.95 at 75°; 49.87 at 100°. Sol in hot alcohol, in alkali hydroxides. Insol in chloroform.
pKa: pK1 2.38; pK2 9.39
Optical Rotation: [a]D23 -31.5° (c = 1); [a]D20 +2.4° (0.5N HCl); [a]D20 +0.15° (c = 2.43 in 0.5N NaOH)
Derivative Type: Hydrochloride
Molecular Formula: C11H12N2O2.HCl
Molecular Weight: 240.69
Percent Composition: C 54.89%, H 5.44%, N 11.64%, O 13.29%, Cl 14.73%
Properties: Needles from methanol, dec 251°.
Use: Probe for studying protein structure and dynamics.
Therap-Cat: In treatment of depression, schizophrenia and other neuropsychiatric disorders.
Keywords: Antidepressant.
Tryptophol TSQ Tsuduranine Tuaminoheptane Tuberactinomycin

Skeletal formula of L-isomer
Ball-and-stick model of L-isomer
CAS number 73-22-3 YesY
PubChem 6305
ChemSpider 6066 YesY
DrugBank DB00150
KEGG D00020 YesY
IUPHAR ligand 717
ATC code N06AX02
Jmol-3D images Image 1
Molecular 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)[1]
Supplementary data page
Structure and
n, εr, etc.
Phase behaviour
Solid, liquid, gas
Spectral data UV, IR, NMR, MS
 N (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Tryptophan (IUPAC-IUBMB abbreviation: Trp or W; IUPAC abbreviation: L-Trp or D-Trp; sold for medical use as Tryptan)[2] is one of the 22 standard amino acids and an essential amino acid in the human diet, as demonstrated by its growth effects on rats. It is encoded in the standard genetic code as the codon UGG. Only the L-stereoisomer of tryptophan is used in structural or enzyme proteins, but the R -stereoisomer is occasionally found in naturally produced peptides (for example, the marine venom peptide contryphan).[3] The distinguishing structural characteristic of tryptophan is that it contains an indole functional group.