Abstract
Using the purified tyrosinase from potato, the oxidation of normal-dihydrothiamine to thiamine was tested with the following results.
1. In pyrocatechol-tyrosinase system about 20% of the dihydrothiamine added was oxidized to thiamine. When either tyrosinase or pyrocatechol was omitted from the reaction mixture, the amount of thiamine formed decreased to less than 1%.
2. The amount of thiamine formed increased in proportion to the amount of the enzyme and of pyrocatechol used and the thiamine formation reached the saturation level in the presence of a definite amount of these components, no further increase being observed.
3. The optimal pH level for thiamine formation was 6 to 7, the activity being decreased rapidly in either acidic or alkaline side.
4. The thiamine formation was highest in pyrocatechol-tyrosinase system than in cresolase system.
