小麦谷氨酸脱羧酶的纯化及部分性质研究

谷氨酸脱羧酶（ｇｌｕｔａｍａｔｅｄｅｃａｒｂｏｘｙｌａｓｅ，ＧＡＤ，ＥＣ４．１．１．１５）催化谷氨酸脱羧生成γ－氨基丁酸（γ－ａｍｉｎｏｂｕｔｙｒａｔｅ，ＢＡ），植物中已从南瓜［１］、马铃薯和林生山黧豆［２］纯化了ＧＡＤ．ＧＡＤ活性在禾本科作物中作为...

Purification and Some Properties of Glutamate Decarboxylase from Wheat Seedling

Glutamate Decarboxylase (GAD) was purified from wheat seedling in order to study its function during germination on stress.The purification steps included PEG6000 fractionation,DEAE Sepharose CL 6B,Sephadex G 200 and Lys Sepharose 4B chromatography.Its final specific activity was 29 U/mg protein at pH 5 8 with 138 purification folds and 10% yields.The wheat GAS had a M r of approximately 310 kD using Sephadex G 200 gel filtration.It was a hexamer with a subunit molecular weight of 50 kD as shown by SDS PAGE.The K m value for γ aminobutyrate was estimated to be 8.5 mmol/L.Determination of the p I and pH optimuim revealed 4.8 and 5.8 respectively.The enzyme was stable for a month at 4℃ in the dark at a concentration of 20 mmol/L PBS buffer including 0.4 mmol/L PLP and 0 1 mmol/L 2 mercaptoethanol and was heat stable up to 55℃.It showed strict specificity for the substrate.The GAD activity was inhibited by 2 mmol/L dithiothreitol and 0 1 mmol/L phenylethylsulfonyl fluoride(PMSF).