The formation of α-d-(1→3) branch linkages by an exocellular glucansucrase from Leuconostoc mesenteroides NRRL B-742

✍ Scribed by Gregory L. Côté; John F. Robyt

• Publisher: Elsevier Science
• Year: 1983
• Tongue: English
• Weight: 1002 KB
• Volume: 119
• Category: Article
• ISSN: 0008-6215
• DOI: 10.1016/0008-6215(83)84053-1

✦ Synopsis

Leuconostoc mesenteroides NRRL B-742 produces two exocellular cu-D-glucans, namely, fraction L, which consists of an a-~-( l-6) backbone with (u-~-(1-+4) branch-points, and fraction S, which consists of an LY-D-(I-6) backbone with LY-D-(l-+3) branch-points. It was found that the percentage of a-D-(1-+3) branch-points in fraction S glucan is variable, depending on the conditions under which it is synthesized from sucrose by the exocellular glucansucrase, and that a-D-(1-+3) branch formation by this glucansucrase occurs by acceptor reactions in which cu-D-glucosyl groups are transferred from sucrose to OH-3 groups on cr-D-(l-&)-linked D-glucan chains. Thus, any change in reaction conditions that affects the rate of acceptor reactions relative to chain elongation also affects the degree of branching in B-742 fraction S dextran. It was also found that this glucansucrase is capable of modifying other dextrans, such as B-S12F and B-742 fraction L,, by transferring D-glucosyl groups to OH-3 of D-glucosyl residues in these dextrans as well.