Maltodextrins (dextrins) are glucose chains normally produced by starch hydrolysis. Maltodextrins are characterized by their degree of polymerization (DP), which indicates the average number of glucose units per chain. Maltoheptaose (DP7), also known as amyloheptaose, is one of the maltodextrin mixtures widely used in foods, cosmetics, and pharmaceutical industries. Recently, the enzymatic synthesis of DP7 has attracted considerable attention, owing to its considerable advantages over chemical methods. In this work, we have designed a one-pot cascade reaction bio-synthesis starting from soluble starch to produce a specific degree of polymerization (DP7). The reaction system was catalyzed by cyclodextrin glucotransferase (GaCGT) from Gracilibacillus alcaliphilus SK51.001CGTase (transglycosylation/cyclization reaction) and cyclomaltodextrinase (BsCD) from Bacillus sphaericus E-244CDase (ring-opening reaction). The one-pot cascade reaction exhibited an optimum temperature of 30 °C and pH 7.0, and the addition of Ca²⁺ enhanced the maltoheptaose production. The optimum enzyme units for the one-pot cascade reaction were 80 U/g of GaCGT and 1 U/g of BsCD. However, the sequential addition of the enzymes exhibited a 5-fold higher conversion rate over simultaneous addition. The one-pot cascade reaction converted 30 g/L of soluble starch to 5.4 g/L of maltoheptaose in 1 h reaction time with a conversion rate of 16 %.

麦芽糖糊精（糊精）是通常由淀粉水解产生的葡萄糖链。麦芽糖糊精的特征在于它们的聚合度 (DP)，它表示每条链的平均葡萄糖单元数。麦芽七糖 (DP7)，也称为淀粉七糖，是广泛用于食品、化妆品和制药行业的麦芽糊精混合物之一。最近，DP7 的酶促合成由于其相对于化学方法的显着优势而引起了相当大的关注。在这项工作中，我们设计了一种从可溶性淀粉开始的一锅级联反应生物合成，以产生特定的聚合度 (DP7)。反应体系由嗜碱芽孢杆菌的环糊精葡萄糖转移酶（Ga CGT）催化来自球形芽孢杆菌E-244CDase（开环反应）的 SK51.001CGTase（转糖基化/环化反应）和环麦芽糖糊精酶 ( BsCD )。一锅级联反应的最适温度为 30 °C，pH 为 7.0，Ca ^{2+ 的加入}提高了麦芽七糖的产量。一锅级联反应的最佳酶单位为80 U/g Ga CGT 和1 U/g BsCD。然而，酶的连续添加表现出比同时添加高 5 倍的转化率。一锅级联反应在 1 小时的反应时间内将 30 g/L 的可溶性淀粉转化为 5.4 g/L 的麦芽七糖，转化率为 16%。