海洋环境来源的淀粉酶AmyP对生玉米淀粉的降解特性

Degradation of Raw Corn Starch by an α-Amylase(AmyP) from Marine Environment

来自海洋宏基因组文库的α-淀粉酶(AmyP)属于最新建立的糖苷水解酶亚家族GH13_37。AmyP是一个生淀粉降解酶,能有效降解玉米生淀粉。在最适反应条件pH 7.5和40℃下,生玉米淀粉的比活达到(39.6±1.4)U/mg。酶解反应动力学显示AmyP可以非常快速的降解生玉米淀粉。对1%的生玉米淀粉降解仅需要30min;4%和8%的生玉米淀粉只需3h。DTT可以显著提高AmyP对生玉米淀粉的降解活性,1%DTT促使活性增加1倍。根据电镜观察和产物分析,认为AmyP是以内腐蚀的模式降解生玉米淀粉颗粒,释放出葡萄糖、麦芽糖和麦芽三糖作为终产物。

The α-amylase （AmyP） from a marine metagenomic library belongs to the recently classified glycoside hydrolase subfamily GH13_37. AmyP is raw starch degrading enzyme, exhibiting a remarkable ability to digest raw corn starch. The specific activity of raw corn starch was reached （ 39.6 ± 1.4） U/mg under the optimum pH 7.5 and temperature 40℃. The hydrolysis curve showed that AmyP could hydrolyze raw corn starch at a very high speed. The final hydrolysis degrees were obtained in 30min for 1% raw corn starch and 3h for 4% and 8% concentration. The enzyme＇ s activity was greatly increased in the presence of DTY. 1% DTT led to a twofold-enhanced activity. The results of scanning electron microscopy and thin-layer chromatography show that AmyP attacks sites on raw corn starch granules with a mode of endo-corrosion, and releases glucose, maltose and mahotriose as end products.