Kinetic characterisation of the light-driven protochlorophyllide oxidoreductase (POR) from Thermosynechococcus elongatus
Kinetic characterisation of the light-driven protochlorophyllide oxidoreductase (POR) from Thermosynechococcus elongatus
复制标题
细长嗜聚球藻光驱动原叶绿素氧化还原酶 (POR) 的动力学表征
DOI：
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发表时间：
2005
影响因子：
3.1
通讯作者：
D. Heyes
中科院分区：
文献类型：
--
作者：
M. Mcfarlane;C. Hunter;D. Heyes
光驱动酶NADPH：原叶绿素氧化还原酶（POR）催化原叶绿素（Pchlide）的C17-C18双键还原为叶绿素（Chlide），这是叶绿素生物合成途径中的关键调节步骤。POR从嗜热蓝细菌Thermosynechococcus elongatus是一个有吸引力的系统以下的反应，在本工作中，我们已经进行了详细的稳态动力学表征这种酶。嗜热POR显示在约50 °C下具有最大活性，这与生物体的生长温度相似。计算得出V _max为0.53 μM min^-1，NADPH和Pchlide的K _m值分别为0.013 μM和1.8 μM。通过荧光发射测量分析了两种底物以及NADP^+产物的结合特性，从而计算出结合的解离常数。这些结果代表了POR的嗜热版本的第一个稳态动力学表征。
The light-driven enzyme NADPH:protochlorophyllide oxidoreductase (POR) catalyses the reduction of the C17-C18 double bond of protochlorophyllide (Pchlide) to chlorophyllide (Chlide), which is a key regulatory step in the chlorophyll biosynthesis pathway. POR from the thermophilic cyanobacterium Thermosynechococcus elongatus is an attractive system for following the reaction and in the present work we have carried out a detailed steady state kinetic characterisation of this enzyme. The thermophilic POR was shown to have maximal activity at approximately 50 °C, which is similar to the growth temperature of the organism. The V _max was calculated to be 0.53 μM min^−1 and the K _m values for NADPH and Pchlide were 0.013 μM and 1.8 μM, respectively. The binding properties for both substrates as well as the NADP^+ product have been analysed by using fluorescence emission measurements, which have allowed the dissociation constants for binding to be calculated. These results represent the first steady state kinetic characterisation of a thermophilic version of POR.