钙离子对香蕉谷氨酸脱羧酶贮藏的改善作用  

Improving the Storage of Glutamate Decarboxylase from Fresh Banana by Calcium Ions

作　　者：钱莉[1] 缪冶炼[1] 陈介余 王琲[1] 王冀宁[3] 

机构地区：[1]南京工业大学食品与轻工学院材料化学工程国家重点实验室,南京211816 [2]日本秋田县立大学生物资源学部 [3]南京工业大学经济管理学院,南京211816

出　　处：《中国食品学报》2013年第11期106-110,共5页Journal of Chinese Institute Of Food Science and Technology

基　　金：国家重点基础研究发展计划(973项目;2009CB724700);国家自然科学基金项目(71173103/G0310)

摘　　要：采用香蕉谷氨酸脱羧酶（GAD）进行发芽大豆的均相反应,能够大幅提高γ-氨基丁酸（GABA）的产率。然而,GAD在贮藏中容易失活。本文旨在把握贮藏过程中GAD活力的变化规律,揭示钙离子Ca2＋对GAD贮藏的影响。从新鲜香蕉中提取GAD,将GAD酶液（pH 5.5）在Ca2＋质量浓度0~80 mg/L、贮藏温度5~35℃的条件下贮藏,对GAD活力变化进行动力学分析。试验结果表明,GAD失活为一级反应,反应速率常数与温度的关系符合Arrhenius方程。未添加Ca2＋时,GAD失活的反应速率常数为0.27 1/d,活化能为8.2 kJ/mol。当Ca2＋质量浓度为30 mg/L时,反应速率常数降低到最小值0.075 1/d,而活化能上升到最大值18.3 kJ/mol,Ca2＋对GAD贮藏有显著的改善作用。可以推测,Ca2＋的存在不仅促进了GAD与钙调素（CaM）的结合,而且减少了PLP与酶蛋白的解离以及酶蛋白构象的改变。本研究成果为开发香蕉GAD贮藏技术提供了理论依据和技术数据。γ-aminobutyric acid （GABA） is produced effectively during the homogeneous reaction of germinated soy- beans with glutamate decarboxylase（GAD）. However, the GAD from fresh banana is unstable in storage. The objectives of present study were to understand the change pattern of GAD activity in storage, and to clarify the effect of calcium ions （Ca2＋） on GAD storage. GAD was extracted from fresh banana, and then the GAD solution（pH 5.5） was stored under the conditions of a Ca2＋ concentration in the range of 0-80 mg/L and a temperature in the range of 5-35 ℃. The changes of GAD activity during storage were investigated and discussed kinetically. Experimental results showed that GAD inactiva- tion was a one-order reaction, and the relationship of reaction rate constant and temperature followed Arrhenius equation. When Ca2＋ was not added, the GAD inactivation had a reaction rate constant of 0.27 1/d and an activation energy of 8.2 kJ/mol. The reaction rate constant was decreased to a minimum of 0.075 l/d, and the activation energy was increased to a maximum of 18.3 kJ/mol by adding Ca2＋ at a concentration of 30 mg/L. It was suggested that the Ca2＋ not only en- hanced the connection of GAD and calmodulin （CAM）, and but also reduced the dissociation of PLP from zymoproteins and the changes of zymoprotein structures. The present work provided theoretical basis and technical data for developing the storage technology of GAD from fresh banana.

关 键 词：Γ-氨基丁酸 香蕉 谷氨酸脱羧酶 钙离子 贮藏 功能性食品 

分 类 号：TS255.4[轻工技术与工程—农产品加工及贮藏工程]