Regulation of the photosynthetic electron transport chain
Regulation of the photosynthetic electron transport chain
复制标题
光合电子传递链的调节
DOI：
10.1007/s004250050629
复制
发表时间：
1999
期刊：
影响因子：
4.3
通讯作者：
G. Johnson
中科院分区：
文献类型：
--
作者：
T. Ott;Joanne Clarke;Katharine Birks;G. Johnson
本文研究了植物二色蝇子草（Silene dioicaL.）光系统Ⅱ和Ⅰ之间电子传递的调节。通过测量P700从亮到暗转变后的还原动力学。结果发现，在这个物种中，P700还原的速率常数是敏感的光强度和CO2的可用性。结果表明，在25 °C下，电子传递速率相对于饱和CO2中可达到的最大速率下调约40-50%，并且这种下调可以通过电子传递链本身的调节来解释。对该速率常数的温度敏感性的测量表明，在20 °C左右控制电子传递的限速步骤中存在一个开关：在较高温度下，CO2的可用性受到限制;在较低温度下，一些其他过程调节电子传递，可能是电子传递链本身内的扩散步骤。电子传递的调节也发生在响应干旱胁迫和蔗糖喂养。非光化学猝灭叶绿素荧光的测量不支持的想法，即电子传递是由跨类囊体膜的pH梯度调节，并讨论了基质成分的氧化还原电位可能调节电子传递的可能性。
The regulation of electron transport between photosystems II and I was investigated in the plantSilene dioicaL. by means of measurement of the kinetics of reduction of P700following a light-to-dark transition. It was found that, in this species, the rate constant for P700reduction is sensitive to light intensity and to the availability of CO2. The results indicated that at 25 °C the rate of electron transport is down-regulated by approximately 40–50% relative to the maximum rate achievable in saturating CO2and that this down-regulation can be explained by regulation of the electron transport chain itself. Measurements of the temperature sensitivity of this rate constant indicated that there is a switch in the rate-limiting step that controls electron transport at around 20 °C: at higher temperatures, CO2availability is limiting; at lower temperatures some other process regulates electron transport, possibly a diffusion step within the electron transport chain itself. Regulation of electron transport also occurred in response to drought stress and sucrose feeding. Measurements of non-photochemical quenching of chlorophyll fluorescence did not support the idea that electron transport is regulated by the pH gradient across the thylakoid membrane, and the possibility is discussed that the redox potential of a stromal component may regulate electron transport.