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研究了稀土离子（Ｌｎ３ ＋） 对烟草（Ｎｉｃｏｔｉａｎａ ｔａｂａｃｕｍ）１ ，５ － 二磷酸核酮糖羧化酶（ＲｕＢＰｃａｓｅ）活力的影响。结果表明，在该酶的反应体系中，用Ｌｎ３ ＋ 替代Ｍｇ２ ＋ ，烟草ＲｕＢＰｃａｓｅ 的活力随Ｌｎ３ ＋ 浓度的变化曲线呈双相效应， 即在高浓度时， Ｌｎ３ ＋ 抑制该酶活性； 低浓度的Ｌｎ３ ＋ 提高ＲｕＢＰｃａｓｅ 活性。其活化效应为轻稀土离子大于重稀土离子，但Ｌｎ３ ＋ 的活化效应低于Ｍｇ２ ＋ 。在有Ｍｇ２ ＋ 的反应体系中，Ｌｎ３ ＋ 在低浓度时也有提高ＲｕＢＰｃａｓｅ 活性的能力，提高幅度较低；而高浓度的Ｌｎ３ ＋ 显著地抑制酶活性。进一步对ＲｕＢＰｃａｓｅ － Ｌａ 二元复合物的ＥＸＦＡＳ 研究，证实Ｌａ３ ＋ 与ＲｕＢＰｃａｓｅ 氨基酸残基的Ｏ 原子键合，键长为２ ．５１?；Ｌａ３ ＋ 还与Ｓ 原子结合。最后对Ｌｎ３ ＋ 和ＲｕＢＰｃａｓｅ 相互作用的分子机制进行讨论
The effect of rare earth ion (Ln3 +) on the activity of Nicotiana tabacum 1, RuBPcase 1 was studied. The results showed that in the enzyme reaction system, Ln3 + instead of Mg2 +, the activity of tobacco RuBPcase with Ln3 + concentration curve showed a biphasic effect, that is, at high concentrations, Ln3 + inhibition of the enzyme activity; low concentration Ln3 + increases RuBPcase activity. The activation effect of light rare earth ions is greater than heavy rare earth ions, but Ln3 + activation effect is lower than Mg2 +. In Mg2 + -containing reaction system, Ln3 + also had the ability of increasing the activity of RuBPcase at a low concentration, with a lower increase rate; while Ln3 + at a high concentration significantly inhibited enzyme activity. Further studies on the RuBPcase - La binary complex by EXFAS confirmed that La3 + is bonded to the O atom of the RuBPcase amino acid residue with a bond length of 2. 51?; La3 + also binds to the S atom. Finally, the molecular mechanism of the interaction between Ln3 + and RuBPcase is discussed