Hopkins–Cole reaction
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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
- ↑ R.A. Joshi (2006). Question Bank of Biochemistry . New Age International. p. 64. ISBN 978-81-224-1736-4 .
- ↑ Debajyoti Das (1980). Biochemistry . Academic Publishers. p. 56. ISBN 978-93-80599-17-5 .
- ↑ P. M. Swamy (2008). Laboratory Manual on Biotechnology . Rastogi Publications. p. 90. ISBN 978-81-7133-918-1 .
- ↑ Chatterjea (1 January 2004). Textbook of Biochemistry for Dental/Nursing/Pharmacy Students . Jaypee Brothers Publishers. p. 51. ISBN 978-81-8061-204-6 .
- ↑ Hopkins, Frederick Gowland ; Cole, Sydney W. (1901). "On the proteid reaction of Adamkiewicz, with contributions to the chemistry of glyoxylic acid". Proceedings of the Royal Society . 68 (442–450): 21–33. doi : 10.1098/rspl.1901.0008 . S2CID 84899015 .
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