35 



in the dahlia and beet is due to a peculiar oxidizer. This he has 

 been able to separate and has called it "Tyrosinase". It exists 

 not only in the dahlia and beet but in several varieties of mush- 

 rooms which do not contain ty rosin. 



Tyrosinase is very unstable. It is best prepared from Rus- 

 sules. 



One can either use juice of the mushrooms at once, or pre- 

 serve them for future use by cutting in thin slices and drying in 

 a vacuum. When wanted for use the dried residue is macerated 

 for some time in cold water and then filtered. 



If a solution of tyrosinase is mixed with a solution of ty- 

 rosin and the liquid frequently shaken to introduce air the liquid 

 will first turn red, then black. Tyrosinase is not so frequently 

 found in plants as laccase, but may be found in many fungi such 

 as Russula, Lactarius, Hebeloma, Boletus, Amonita, and many 

 others. 



The two enzymes frequently exist in the same plants. Bert- 

 rand found that tyrosinase was more easily destroyed by heat 

 than laccase. 



Bertrand 39 gives the following as the theory of the action of 

 oxydizing enzymes. That the manganese, which is present in all 

 enzymes, even as high as 2%, exists in the albuminous substance 

 as a manganous compound, and plays the part of oxygen carrier. 

 The oxygen molecule is broken by the manganous compound to 

 form manganese dioxide and the remainder of the oxygen mole- 

 cule acts upon the oxydizible body present. Finally through the 

 acid character of the albumen radical, the manganese dioxide is 

 decomposed and the original manganese compound restored. He 

 believes that the activity of the enzyme is proportional to the 

 manganese present. 



Bourquelot 40 reports upon the action of tyrosinase on phenols, 

 etc. He states that the tyrosinase of mushrooms forms with gua- 

 iacol a red precipitate. 



Bokorny 41 after giving the apparent similarity of enzymes 

 and protoplasm, especially with reference to the action of light 

 and temperature, concludes that one can scarcely think that they 

 originate from the same source. 



39 Compt. rend. 124, 1356, 1897. 



40 Repertoire de Pharmacie, 1897, p. 136. 



41 Allgeminen Brauer und Hopfen Zeitung, No. 74, 1901. 



