水溶性(1→3)(1→6)-α-D-葡聚糖的酶法合成与结构解析

Biosynthesis and structural analysis of water-soluble( 1→3)( 1→6)-α-D-glucan produced by glucansucrase

以蔗糖为底物,利用葡聚糖蔗糖酶的聚合反应来制备(1→3)(1→6)-α-D-葡聚糖,通过探讨优化酶促催化条件参数来合成新型葡聚糖,并采用现代分析仪器解析其结构特征。结果表明,葡聚糖蔗糖酶催化反应条件为:反应温度40℃,蔗糖质量浓度160 mg/m L,加酶量10 U/m L,酶反应时间1 h,反应p H 5.0。分子量分布曲线显示葡聚糖分子质量分布集中并呈单峰,绝对重均分子质量2.4×107g/mol,分散系数为1.07,红外与核磁图谱显示糖链中主要由α-1,3和α-1,6连接的D-吡喃葡萄糖单元组成,且两者的比例约为3∶4。

This paper studied the optimal biosynthesis conditions for water-soluble（ 1 →3）（ 1 →6）-α-D-glucan produced by glucansucrase using sucrose as substrate and its structure was investigated by modern analysis instruments. The optimal reaction conditions were as follows： temperature of 40 ℃,substrate concentration of 160 mg / m L,enzyme concentration of 10 U / m L,and reaction time of 1 h,and p H 5. 0. The HPSEC chromatograms of the polysaccharide appeared as a single symmetrical narrow peak. The weight-average molecular weight of this glucan was 2. 407× 107 g / mol,and the value of Mw / Mn was 1. 07. Results from FT-IR and1H-NMR suggested that this glucan was mainly composed of α-1,3 and α-1,6 linked D-glucopyranose units with ratio of approximately 3∶ 4.