莱茵衣藻突变体与野生型RUBISCO酶动力学参数的比较研究

COMPARATIVE STUDIES ON ENZYMATIC KINETICS PARAMETERS OF RIBULOSE 1,5 BISPHOSPHATE CARBOXYLASE/OXYGENASE IN CHLAMYDOMONAS REINHARDTII

以莱茵衣藻的Ｒｕｂｉｓｃｏ 突变体６９－１２Ｑ＋ ，６８－４ＰＰ＋ 和野生型２１３７＋ 为材料，分析比较了Ｒｕｂｉｓｃｏ 粗酶在不同温度、不同ｐＨ条件下的初始活性，２５℃时的总活性，酶的最适温度，最适ｐＨ和粗酶的活化百分数。用Ｋｏｓｔｏｖ 和ＭｃＦａｄｄｅｎ 的作图法测定了３ 个品系Ｒｕｂｉｓｃｏ 纯化酶在２５℃时的ＣＯ２／Ｏ２ 特征因子Ω值，结果６９－１２Ｑ＋ 的Ω＝ １３；６８－４ＰＰ＋ 的为５４；２１３７＋ 则为６１。上述结果显示Ｒｕｂｉｓｃｏ 大亚基上氨基酸的替换， 必然引起Ｒｕｂｉｓｃｏ 结构的变化，从而引起Ｒｕｂｉｓｃｏ 酶催化特性改变。作图法测定Ω值操作简便、快速、准确，优于传统方法。

We have investigated the kinetic parameters of ribulose 1,5 bisphosphate carboxylase/oxygenase (Rubisco) and determine CO 2/O 2 specificity factor (Ω).Initial activities of rude enzyme of Rubisco in various temperature,various pH, and total enzyme activities at 25℃ were assayed among the Rubisco mutants 69 12Q +,68 4PP + and wild type 2137 + in Chlamydomonas reinhardtii.The rude enzyme′s optimum temperature,optimum pH and percentage of activation were determined.Analyses of CO 2/O 2 specificity factor Ω of purified Rubisco were conducted with Kostov and McFadden′s graphical method.The Ω values for 69 12Q +,68 4PP + and 2137 + are 13,54,and 61 respectively.Our results indicated that subtle perturbation of Rubisco subunit may exert signification effects on its catalytic properties and the Ω value can be altered by the manipulation of Rubisco molecular.Graphical determination of the CO 2/O 2 specificity factor is superior in simplicity, celerity and accuracy to traditional methods.