抄録
1. A strain of Leuc. mesenteroides was found to secrete an extracellular enzyme revealing formation of riboflavinylglucoside from sucrose and riboflavin.
2. The enzyme was isolated from the cell-free culture fluid of the bacterium grown on a sucrose medium by precipitation with ammonium sulfate and by reprecipitation with acetone.
3. Maximum activity of the enzyme was observed in the range of pH 5.0-5.6 and at 25-30°. The enzyme showed higher stability at 25° and was found to be fairly sensitive to heat as it was destroyed in a few minutes at 40°, even at pH 5.3.
4. It was found that the enzyme revealed high specificity on sucrose, since any other sugars failed to act as the glucosyl donor for the formation of riboflavinylglucoside. Moreover, the enzyme formation was observed only in a sucrose medium.
5. Maltose showed a strong inhibitory effect on the formation of riboflavinylglucoside and Cu2+, Fe2+ and Fe3+ also acted as powerful inhibitors.
