STUDIES ON DEXTRANSUCRASE

V. FORMATION OF RIBOFLAVINYLGLUCOSIDE BY THE INTRACELLULAR ENZYME OF LEUCONOSTOC MESENTEROIDES GROWN ON SUCROSE

Abstract

1. Cell-free extracts prepared from strains of Leuc. mesenteroides grown on sucrose were found to reveal the production of riboflavinylglucoside from sucrose and riboflavin. Moreover, it was found that the extract utilized only sucrose as a glucosyl donor in the formation of riboflavinylglucoside, while glucose itself was quite ineffective.
2. The intracellular enzyme revealing formation of riboflavinylglucoside was isolated by ammonium sulfate precipitation from the cell-free extract of the strain NRRL B-1299 grown on sucrose.
3. Maximum activity of the enzyme was observed in the range of pH 4.5 to 5.3 and around at 30°. The enzyme was found to be fairly sensitive to heat as it was almost completely inactivated by heating at 45° for 10 minutes.
4. By the action of the enzyme, riboflavinyloligosaccharides were observed to be formed through the successive transfer of glucosyl group between riboflavin compounds and sucrose.