Tryptophan ELISA Kit (Trp)


Human tryptophan ELISA kit is a method designed for detecting in vitro quantitative concentrations of tryptophan (Trp) human serum, plasma and urine samples. This assay has a minimum detection limit of 1.2 µg/ml.


Tryptophan (abbreviated to Trp or W) is a natural amino acid that is a common precursor to a number of biologically important active molecule which includes serotonin and melatonin. It can be oxidized by the hormone-sensitive enzyme called tryptophan oxygenase to N-formyl kynurenine, this can then follow a series of steps which produces to amino-carboxymuconic semi-aldehyde. Most of this is able to undergo an enzymatic decarboxylation process which ultimately leads to acetyl CoA being formed.

Tryptophan is an alpha amino acid that is essential in the biosynthesis of many proteins. It can be classified as a non-polar aromatic amino acid which consists of an α-amino group, an α-carboxylic acid group and a side chain indole. It is an essential amino acid, so the body is unable to synthesis it and therefore it must be obtained from the diet. Infants and children require greater amount of tryptophan when compared to adults in order to enable normal development and growth. The body needs it in order to manufacture several important substances and diets which are deficient have been known to result in pellagra (a niacin deficiency disease).

Many research trials have been published that have shown that measuring the levels of tryptophan concentrations can be used in treating sleep disorders, seasonal affective disorder, premenstrual discomfort and for reducing anxiety when quitting smoking. It is well known that the human body uses L-tryptophan in order to produce serotonin and melatonin. Serotonin plays an important role in regulating sleep, appetite, pain and mood. Whereas, melatonin is vital during the sleep-wake cycle.


All reagents supplied need to be stored at 2 °C – 8 °C, unopened reagents will retain reactivity until expiration date. Do not use reagents beyond this date.

  • Adhesive Foil.
  • Reaction Plate: 1x 96 well plate (empty).
  • Wash Buffer Concentrate (50x).
  • Enzyme Conjugate.
  • Substrate (Tetramethylbenzidine).
  • Stop Solution.
  • Tryptophan Microtiter Strips: Antigen pre-coated microwell plate.
  • Antiserum – Rabbit anti-tryptophan antibody.
  • Standards (A-F): Concentrations 0, 2.5, 7.5, 25, 75, 250 µg/ml.
  • Controls (1+2) – 0-250 µg/ml.
  • Assay Buffer.
  • Equalizing Reagent (Lyophilized).
  • D-Reagent: Crosslinking agent in dimethylsulfoxide.
  • Q-Buffer.
  • Phosphate Buffered Saline (PBS).
  • Precipitating Reagent.


The minimum detection sensitivity level of Trp (tryptophan) using current tryptophan ELISA kit was approximately 1.2 µg/ml. The dynamic range for this assay is 2.5 – 250 µg/ml.


– Tryptophan (Trp): ELISA
– Analytical Sensitivity (Limit of Detection): 1.2 µg/ml
– Expected Reference Values: 1.5 – 40 (µg/g creatinine; Adults > 18y)(Urine) and 9.3 – 17 (µg/mL; Adults > 16y)(Plasma/Serum).
– Analytical Sensitivity (Cross Reactivity): Tryptophan (100%), Tryptamine (0.2%), 5-Methoxytryptophan, 5-Hydroxytryptamine, 5-Hydroxy-L-tryptophan, N-acetyl-5-hydroxytryptamine (< 0.01%).
– Precision Intra Assay: 11 – 11%
– Precision Inter Assay: 8.4 – 15.0%
– Linearity: 101 – 129% (Urine)
– Recovery: 104 – 110% (Urine) and 86 – 100% (Serum)


  1. The role of the kynurenine pathway of tryptophan-metabolism in cardiovascular disease. An emerging field. Hamostaseologie. (2015) 35 (2): 128-36. Review. Polyzos K.A. and Ketelhuth D.F.
  2. Possible roles of excess tryptophan metabolites in cancer. Environ Mol Mutagen. (2011) 52 (2): 81-104. Review. Chung K.T. and Gadupudi G.S.
  3. Targeting key dioxygenases in tryptophan-kynurenine metabolism for immunomodulation and cancer chemotherapy. Drug Discov Today. (2015) 20 (5): 609-17. Review. Austin C.J. and Rendina L.M.
  4. Tryptophan Metabolism in Allergic Disorders. Int Arch Allergy Immunol. (2016) 169 (4): 203-15. Review. Gostner J.M., et al.


  • Full Name: Tryptophan ELISA Kit (Trp)
  • Reactivity: Human
  • Sample Type: Serum, Urine, Plasma
  • Sensitivity: 1.2 µg/ml


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