Tyrosine specific color reactions

Some individual amino acids could be detected by specific color reactions such as the Millon reaction for tyrosine (1849), the Hopkins-... 

The protein molecule has free carboxyl and amino groups. Therefore it exhibits amphoteric properties. A number of color reactions have been developed for proteins to determine the presence of specific amino acids. The following are among the most important Millon s reaction. This reaction consists in the development of a red coloration when a substance containing a monohydroxyben-zene group is heated with a mixture of mercuric nitrate and nitrite (MUlon s reagent). Proteins giving this reaction contain tyrosine. 

Pauly s diazo reaction is more specific for all iododerivatives of tyrosine, thyronine, and histidine, and it is also more sensitive (31). The technique described by Block and Bolling (2) is suitable. The colors of the spots are given in Table II. 

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