发芽粟谷中谷氨酸脱羧酶的主要酶学性质初探

目的]探讨发芽粟谷Setaria italica（L.）Beauv.]中谷氨酸脱羧酶（GAD）的主要酶学性质。方法]以发芽粟谷为试材,研究发芽粟谷GAD的活性及其主要酶学性质。结果]发芽粟谷GAD最适温度为40℃,其耐热性较差,32℃保温1 h后其酶活保持率为86.3%;发芽粟谷GAD最适pH值为5.5,在pH值5.0～5.5范围内酶活保持率在80.0%以上;发芽粟GAD对Glu的Km为22.36mmol/L,Vmax为2.28μmol/min;Ca2＋、Mg2＋、Li＋、PLP和VB6对发芽粟谷GAD活力具有促进作用,而Zn2＋、La3＋、Cu2＋起抑制作用,Mn2＋、Na＋、Fe2＋和EGTA则无显著影响。结论]该研究可为利用发芽粟谷内源GAD富集GABA提供理论依据。

Study on Enzymatic Properties of Glutamate Decarboxylase from Germinated Setaria italica (L.)Beauv

Objective] The research aimed to discuss the main enzymatic properties of glutamate decarboxylase(GAD) from germinated Setaria italica(L.) Beauv..Method] With germinated Setaria italica(L.) Beauv.as research object,its GAD activity and some enzymatic properties of were studied.Result] The results showed that GAD from germinated Setaria italica(L.) Beauv.had an optimum temperature at 40 ℃,and its heat resistance was very weak,only exist 86.3% of its activity after keeping in 32 ℃ for an hour.The optimal pH value for germinated Setaria italica(L.) Beauv.was 5.5,GAD activity was stable when pH value was in the range of 5.0-5.5,which could maintain 80.0% activity.Km and Vmax values of germinated Setaria italica(L.) Beauv.GAD to glutamic acid were 22.36 mmol/L and 2.28 μmol/min,respectively.Metal ions and chemical reagents such as Ca2+,Mg2+,Li+,PLP and VB6 increased the GAD activity,and Zn2+,La3+,Cu2+ decreased the enzyme activity,while Mn2+,Na+,Fe2+ and EDTA had no effect on it.Conclusion] The study can provide theoretical basis for utilizing GAD in germinated Setaria italica(L.) Beauv.to gathering γ-aminobutyric acid(GABA).