摘要
研究从土壤中筛选得到的黑曲霉AS0023菌株所产的β-果糖转移酶的一些酶学性质。该酶的最适pH为5.0,最适温度为50℃,有较好的热稳定性和较宽的pH(3.5~10)适宜范围;并研究了12种化学物质对酶活的影响和底物的特异性。结果显示,钴离子对该酶有一定的激活作用;底物分子越大其反应速度越慢。该酶的米氏常数K_m=47mmol,葡萄糖是酶反应的竞争性抑制剂,其K_i=330mmol.当50%(W/v)蔗糖与酶在pH5.0和50℃作用16h时,得到52%(产物/总糖)低聚果糖。
An Aspergillus niger strain AS0023 producing fructosyltransferase(FTS)was selected from soil.The optimum pH and temperature for producing FTS were 5.0 and 50℃, respectively.The advantage of the enzyme were high activity over wide range of pHfrom 3.5 to 10 and good thermostability.The effect of 12 chemical substances on FTSwere tested,among which cobalt ion had a positive effect on the activity of FTS.The K_mvalue of the enzyme on sucrose was 47mmol.Glucose was a competive inhibiter and the K_ivalue was 330mmol.52% FOS (FOS/total sugar)was produced after 50%sucrose solution was incubated with the enzyme at 50℃,pH5.0 for 16 hours.
关键词
低聚糖
糖基转移酶
酶学性质
ligosaccharides
Fructosyltransferase
Microorganisms/Fructo-oligosaccharides(FOS)
β-Fructosyltransferase(FTS)
Aspergillus niger