Hopkins–Cole reaction
The Hopkins-Cole reaction, also known as the glyoxylic acid reaction, is a chemical test used for detecting the presence of tryptophan in proteins.[1] A protein solution is mixed with Hopkins Cole reagent, which consists of glyoxylic acid. Concentrated sulfuric acid is slowly added to form two layers. A purple ring appears between the two layers if the test is positive for tryptophan.[2][3] Nitrites, chlorates, nitrates and excess chlorides prevent the reaction from occurring.[4]
The reaction was first reported by Frederick Gowland Hopkins and Sydney W. Cole in 1901,[5] as part of their work on the first isolation of tryptophan itself.
References
- ISBN 978-81-224-1736-4.
- ISBN 978-93-80599-17-5.
- ISBN 978-81-7133-918-1.
- ISBN 978-81-8061-204-6.
- S2CID 84899015.
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