A simple colorimetric method for the determination of tryptophan
| Autor: | S. M. M. Basha, R. M. Roberts |
|---|---|
| Rok vydání: | 1977 |
| Předmět: |
chemistry.chemical_classification
Indole test Chromatography Tryptophan Biophysics Proteins Cell Biology Alkaline hydrolysis (body disposal) Ethylenediamines Biochemistry Hydrolysate Amino acid chemistry.chemical_compound Hydrolysis chemistry Organic chemistry Colorimetry Absorption (chemistry) Sodium nitrite Molecular Biology |
| Zdroj: | Analytical Biochemistry. 77:378-386 |
| ISSN: | 0003-2697 |
| Popis: | A simple, sensitive, and reproducible colorimetric method for the determination of tryptophan in amounts as low as 2 μg is described. It is based on the oxidation of tryptophan by sodium nitrite and the coupling of the oxidized product to the leucodye N-1-(naphthyl)ethylenediamine dihydrochloride. The purple-pink product has an absorption maximum at 550 nm. There is no interference by carbohydrates, other amino acids, neutral salts, or a number of other compounds likely to be found in tissue hydrolysates. A number of indole derivatives including indole-3-acetic acid also react to give a colored product. Dipeptides containing tryptophan are much less reactive than free tryptophan; hence proteins must be hydrolyzed completely for the method to be useful. The assay is carried out at room temperature and can be modified easily to increase or decrease its sensitivity. It has been employed to determine the tryptophan content of a number of proteins following alkaline hydrolysis. Generally, values obtained were in close agreement with values reported in the literature. |
| Databáze: | OpenAIRE |
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