抄録
Maltosyl(α1→6)α-, β- or γ-cyclodextrin was synthesized from maltose and α-, β- or γ-cyclodextrin, respectively, using Bacillus acidopullulyticus pullulanase (EC 3.2.1.41). More than 40% of each cyclodextrin substrate was converted to the corresponding maltosyl(α1→6)cyclodextrin under the conditions given below; the combined concentration of maltose and cyclodextrin was 70-75% (w/w), the molar ratio of maltose to cyclodextrin was 9-18, and the amount of pullulanase was 100-200units/g of cyclodextrin. The optimum pH and temperature for the formation of maltosyl(α1→6)cyclodextrins were 4.0-4.5 and 60-70°C, respectively. Each maltosyl(α1→6)cyclodextrin produced was separated from noncyclic saccharides, maltose and branched tetraose, by methanol and ethanol precipitations. The maltosyl(α1→6)cyclodextrins were further purified by gel filtration on a Toyopearl HW 40 S column and crystallization from aqueous (for maltosyl(α1→6)α- cyclodextrin) or methanol (for maltosyl(α1→6)β-cyclodextrin) solution. From 10g each of the corresponding cyclodextrin, the yields of the purified maltosyl(α1→6)α-, β- and γ-cylcodextrins were 3.0-3.6g, 2.5-2.8g and 2.2-2.5g, respectively. Identification of the maltosyl(α1→6)cyclodextrins was performed by means of hydrolysis with Klebsiella pneumoniae pullulanase, methylation analysis and 13C-NMR analysis.
