1. In this paper the comparison was made of the action of tyrosinase on various phenolic substances alone or in the presence of a number of amino acids and other amino compounds.
2. Only those phenols, which are likely to produce ortho-quinones on oxydation gave coloured substances and the presence of amino acids markedly accelerated the production of pigments.
3. The oxygen up-take per molecule of
p-cresol or catechol by the action of tyrosinase was found to be one atom more than that corresponding to the formation of ortho-quinone.
4. The presence of amino acids and a series of aromatic amino compounds remarkably accelerated the rate of oxygen consumption. The total amount of oxygen absorbed however was not in any way affected by the addition of amino compounds.
5. The suggestion was made that amino acids combine with orthoquinones produced by the tyrosinase action.
6. Hydroxylamine accelerated the colour development of the tyrosinase system. The oxygen consumption was on the contrary depressed. The discussion was made on the probable cause of this phenomena.
In conclusion the auther wishes to express his sincere thanks to Prof. K. Kodama and Prof. M. Shiraki for their continual interest and much valuable advice during this work, to Assistant Prof. T. Uchino for his kind direction through-out this work.
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