Abstract
Authors found that dihydrothiamine (DHB_1) was oxidized to thiamine to the extent of 20% in the presence of crystalline wheat germ peroxidase and hydrogen peroxide. The rate of the oxidation was maximum at pH 4,and the amount of thiamine produced was dependent upon the activity of the enzyme as well as the concentration of DHB_1. When a phenolic compound such as catechol was added to the reaction mixture, DHB_1 was also oxidized to thiamine to the same extent as above. But the mechanism of these two ractions were different from each other. In the latter reaction the maximal activity was exhibited between pH 6 to 7 and the excess of peroxidase, DHB_1 or phenolic compounds resulted in pronounced decrease of the rate of the oxidation. From the above results authors postulated that DHB_1 might be enzymatically oxidized to thiamine in plant tissues.
