83 
pounds analogous to tyrosin. With phenyl-alanin, phenyl-ethyl- 
amin, phenyl-methyl-amin, phenyl-amino-acetic acid, phenyl- 
propionic acid, phenyl-acetic acid, alanin and glycocoll, no coloration 
was observed. On the other hand, compounds containing phenolic 
hydroxyl were oxidized with the production of characteristic colors, 
as may be seen from the following table: 
Name of compound. 
Color produced with tyrosinase. 
Tyrosin 
Grenadine-red; then inky black. 
Grenadine-red; then olive-black. 
Orange-yellow, orange-red, clear maroon. 
Orange, mahogany-red, brown. 
Orange-yellow, grenadine-red, brown. 
Yellow, orange-yellow, brown. 
Rose, orange, yellow. 
Yellow, orange, red. 
Yellow, orange, red, brown. 
p-hydroxy-phenyl-ethyl-amin 
p-hvdroxy-phenyl-methy 1-afnin 
p-hvdroxy-phenyl-amin 
p-hydroxy-phen vl-propionic acid 
p-hydroxv-phenyl-acetic acid 
p-hydroxy-benzoic acid 
p-cresol 
phenol 
He concludes, therefore, that only substances containing phenolic 
hydroxyl are oxidized by tyrosinase. He found that polypeptids 
are not colored exactly as is tyrosin, but become first yellow, then 
orange, and then mahogany-red, without the production of any pre- 
cipitate. He concludes, therefore, that if in these polypeptids there 
were previous splitting into tyrosin and other products, one should 
obtain the same coloration as with tyrosin, since glycocoll in the pro- 
portion ordinarily found would not modify the action of the tyros- 
inase on tyrosin. In his opinion, it is necessary to separate the chrom- 
ogen in pure condition in order to properly identify it by means of 
tyrosinase. 
The action of tyrosinase from Russula delica on tyrosin, tyrosin- 
containing polypeptids, and certain other compounds, under various 
conditions, lias also been studied by Abderhalden and Guggenheim. 0) 
According to these authors glycocoll, d-alanin, d-valin, 1-prolin, 
d-serin, d, 1-iso-serin, 1-phenyl-alanin, 1-aspartic acid, and d-gluta- 
minic acid are without effect on the action of tyrosinase on tyrosin, 
except in so far as they influence the rapidity of the development of the 
color. Aspartic and glutaminic acids were found to inhibit the action, 
as did also the other amino acids, especially if present in strong 
solution. The action of tyrosinase was also tried on the following 
substances: 1- and d-tyrosin, di-iodotyrosin, 1-phenyl-alanin, homo- 
i gentisic acid, 1-tryptophane, skatol, indol, 1-prolin, and cystme. Of 
these, liomogentisic acid and tryptophane were the only substances 
except tyrosin to show a color change with the ferment. On the 
other hand, polypeptids containing tyrosin residues were colored by 
tyrosinase, the color being modified to some extent by the nature of 
the amino acid combined with the tyrosin in the polypeptid. Halo- 
