光系统Ⅱ颗粒的毫秒延迟荧光的研究

本文主要报导了具有放氧活性的光系统Ⅱ(PSⅡ)颗粒的毫秒延迟荧光(ms-DF)的特性以及NH_4Cl对它的调节作用.

STUDY ON MILL I SECOND DELAYED FLUORESCENCE OF OXYGEN-EVOLVING PS I PARTICLES OF SPINACH

The characteristics of millisecond delayed fluorescence(ms-DF) of oxygen-evolving PS II particles and regulation effect of NH4Cl on the ms-DF have been investigated. The results are in the following:1. ms-DF of oxygen-evolving PS II particles is quite low in comparison with that of chloroplasts, the ratio of their intensities is about one tenth. In the presence of NH4Cl the intensity of ms-DF in PS II particles is obviously increased. This phenomenon is probaly by inhibition effect of NH4C1 on oxygen evolution.2. The inhibition effect of NH4Cl (at the concentration of NH4Cl used for uncoupling photophosphorylation reaction) on oxgen evolution in PS II particles has been observed.3. The comparative study of NH4Cl on oxygen evolution and ms-DF in chloroplasts and in PS II particles shows that NH4Cl has two opposite effects on the appearance of oxygen evolution in chloroplasts, they are: (1) The stimulation effect due to the uncoupling effect of NH4Cl on photophosphorylation reation. (2) The inhibition effect on oxygen evolution system. In the meantime this concentration of NH4Cl has also two effets on ms-DF as a result of above mentioned causes.It is shown from above results that under condition of the strong continuous exciting flash light,the ms-DF of oxygen-evolving PS II particles reflects only the changes of electron transfer from water to PQ in PS II. Its increase can be used as a convenient probe for determing the blacked state of oxidizing side in the PS II.