中文摘要：

研究了米糠谷氨酸脱羧酶（GAD）的酶学性质。结果表明：米糠GAD的最适温度为40℃，最适pH5．6，米糠GAD耐热性较差，60℃下保温0．5h后，酶活下降至65％，保温1h，酶活下降至48％，而70℃时酶就完全失活，而此酶在pH5．5～9都可以保持84％以上的酶活力。米糠GAD对底物和辅酶PLP的Km分别为0.02845mol／L和1．13μmol／L。KI、Ag^2＋、SDS、乙酸对米糠GAD的活力有较大的抑制作用，而Ca^2＋对米糠GAD的活性有较强的激活作用，提高了底物与米糠GAD的亲和力。

英文摘要：

Some properties of glutamate decarboxylase （GAD） from rice bran were studied. The optimal temperature for rice bran GAD is 40℃ and optimal pH is 5.6. The enzyme lost almost all of its activity at 70℃, but it was stable over a pH range of 5.5-9. Km of Rice bran GAD to glutamic acid was 0. 02845 mol/L, and 1. 13μmol/L to PLP. KI, Ag^2＋ , SDS and acetic acid restrained the GAD activity to a great degree. Ca^2＋ showed a positive effect on the GAD activity as it lows down the Km of substrate.