Studies on Dextransucrase Part I Leuconostoc mesenteroides IAM 1046, and the Structure of Enzymatically Synthesized Dextrans

• Published in: Nippon Nōgeikagaku Kaishi Vol. 46; no. 2; pp. 81 - 88
• Main Authors: NIINOBE, Michio, KOBAYASHI, Tsuneo
• Format: Journal Article
• Language: Japanese
• Published: Japan Society for Bioscience, Biotechnology, and Agrochemistry 1972
• ISSN: 0002-1407; 1883-6844
• DOI: 10.1271/nogeikagaku1924.46.81

Dextransucrase produced by L. mesenteroides IAM 1046 was partially purified, its properties examined, and the structure of dextrans formed from sucrose by the enzyme was studied. The enzyme was purified 24- to 56-times by salting-out with ammonium sulfate and column chromatography on DEAE-cellulose. The purified enzyme showed an optimum pH at pH 5.0, and an optimum temperature at 30°C, and was stable at pH 4.0_??_7.5 at 5°C, but inactivated at temperatures above 40°C. Michaelis constant was estimated to be 1.57×10-2 (M) at pH 5.0 and 30°C. The ratio of α-1, 6-, α-1, 4- (or α-1, 2-) and α-1, 3-glucosidic linkages in dextrans produced by growing culture, culture broth, or partially purified enzyme preparations were estimated with periodate oxidation method. The content of α-1, 6-linkage in dextrans produced by growing cells and culture broth was about 60%, while the value was above 80% for dextrans produced by purified enzyme. The mechanism of dextran synthesis was discussed, and it was suggested that the dextran synthesis would be carried out by two or more enzymes, i.e., polymerizing enzyme which catalyzes the formation of α-1, 6-glucosidic linkages, and branching enzyme which catalyzes the formation of other types of linkage.