Cyclic pentasaccharides

Another cyclic pentasaccharide with more complex linkages was discovered also by the Hayashibara group (Watanabe et al, 2005). They found that the enzyme system synthesizing cyclic nigerosyl nigerose (Fig. 17.2a) synthesized a novel cyclic pentasaccharide as a minor product in the same reaction mixture. This cyclic pentasaccharide contains a-1,3-, a-1,6- and a-1.4- linkages as shown in Figure 17.2d. 

Watanabe, H., Nishimoto, T., Aga, H., Kubota, M., Fukuda, S., Kurimoto, M., and Tsujisaka, Y. 2005. Enzymatic synthesis of a novel cyclic pentasaccharide consisting of a-D-glucopyranose with 6-a-glucosyltransferase and 3-a-isomaltosyltransferase. Carb. Res., 340,1577-1582. 

Preparation of linear oligomer, followed by macrocyclization was demonstrated in the case of cyclic pentaose. A cyclomaltopentaose synthesis was achieved by Nakagawa and coworkers through preparation of a linear pentasaccharide 10 (Fig. 7). The linear pentasaccharide was obtained by first utilizing judiciously equipped maltose derivative I (Fig. 8) as an acceptor in a glycosylation with a suitably protected... 

---