A New Decomposition Product of Keratin Which Gives Millon’s Reaction

The red coloration produced by the interaction of an aromatic phenol and Millon’s reagent (mercuricnitrate indilutenitrous acid) is one of the most characteristic of the color reactions of the proteins. Among the nineteen known compounds which form the protein molecule only one, p-oxy-a-amino phenyl propionic acid (tyros’n) is of such a nature as to give a coloration with Millon’s reagent and therefore a positive reaction is taken to prove the presence of tyrosin. In a recent article’ I have shown that the coloration of the integuments of the meal worm (Tenebris molitor) is due to the presence of a tyrosinase, acting upon a ch. omogen. In many respects this chromogen resembles tyrosin, in that it is not precipitated by phosphotungstic acid or by basic lead acetate and in that it gives a strong Millon’s reaction. It differs from tyrosin, however, by being extremely soluble so that when evaporation was carried almost to dryness and a few drops of water were added no tyrosinlike crystals could be obtained, neither did anyotherof the tyrosin tests, excepting the coloration with tyrosinase, produce positive results. While this was a solitary instance no special attention was paid to it, the supposition being that the chromogen was present in exceedingly small amounts and was probably tyrosin.