研究了La对烟草体内RuBPcase总活性和初活性的影响。La在 0～ 80 μmol·L- 1的浓度范围内能增强它的活性 ,酶初活性提高幅度高于总活性 ,表明La可以活化烟草体内RuBPcase。但当La浓度超过 80 μmol·L- 1时 ,活化作用下降甚至抑制酶活性。在RuBPcase的催化体系中 ,La,Ce在一定浓度范围 ( 2～ 8μmol·L- 1)内能够取代该酶的激活剂Mg而激活酶活性 ,对纯化酶液的激活效果要高于粗酶液。 The effects of La on the total activity and initial activity of RuBPcase in tobacco were studied. La increased its activity in the concentration range of 0 ~ 80 μmol·L-1, and the increase of initial activity of enzyme was higher than that of total activity, indicating that La can activate RuBPcase in tobacco. However, when the concentration of La exceeds 80 μmol·L-1, the activation decreases or even inhibits the enzyme activity. In the RuBPcase catalytic system, La and Ce could replace Mg in the range of concentration (2 ~ 8μmol·L-1) to activate enzyme activity, and the activation of purified enzyme solution was higher than that of crude enzyme solution .