3种石斛PEPC羧化酶活力比较

 石斛属植物具有兼性景天酸代谢植物特征，磷酸烯醇式丙酮酸羧化酶是该类植物碳代谢的关键酶。本研究选用3种石斛为材料，测定了其磷酸烯醇式丙酮酸羧化酶活性。结果表明，报春石斛晚间黑暗条件下酶活性较强，凌晨高达25μmolCO2/(m2·s)，而在中午光照最充足时，酶的活性相对较弱；金钗石斛酶活性日变化特点与报春石斛相似，但是活性比较弱；鼓槌石斛的酶活性很弱，通常在8μmolCO2/(m2·s)以下，昼夜变化幅度很小，表现为黑暗状态下比光下更强。

Comparative Study on PEPC Activity in Three Dendrobia Leaves

The species within the genus of Dendrobium exhibited the characteristics of facultative Crassulacean acid metabolism plants. Aiming at clarifying carbon assimilation pathway of dendrobium, three Dendrobia were employed in this study, and measurement of PEPC activity was conducted by the means of ultraviolet spectrophotometer. The results indicated that PEPC activity of D. primulinum from dark leaves was as strong as 25μmolCO2/(m2·s) early morning,whilst it was relatively weak at noon when sun light was bright, which to some certain concluded that D. primulinum showed the characteristics of CAM plant. In terms of diurnal fluctuation of PEPC activity in D. nobile was resembled to D. primulinum. The PEPC activity in D. chrysotoxum was very weak as below 8μmol CO2/（m2·s）,and the magnitude of diurnal fluctuation was small as comparing to other two objects; anyway, its activity from dark leaves was stronger than one from illuminated leaves, the data from the trials means that D. chrysotoxum is inclined to acting via C3 pathway