多变鱼腥藻Mn^2＋,Ca^2＋和Mg^2＋之间取代作用和放氧的研究

借助于电子顺磁共振波谱仪(EPR)探测了多变鱼腥藻中 Mn~(2 )含量的变化。较高浓度的 CaCl_2和 Ca(NO_3),处理引起藻体中结合态 Mn 的游离和藻的放氧活性的下降。当结合Mn 游离量达57％时,放氧活性降为零。MgCl_2处理的效果小于 CaCl_2。较高浓度的 MnCl_2像 EGTA 一样抑制藻的放氧。与对照比较,在 CaCl_2、MgCl_2和 MnCl_2处理下藻体的低温荧光发射光谱发生变化,波长686nm处的肩消失,F_(130)/F_(695)比值下降。本文对光合放氧复合物中离子间可能在其结合位点上发生竞争性取代作用进行了讨论。

STUDIES ON SUBSTITUTIONS AMONG Mn, Ca AND Mg IONS AND OXYGEN EVOLUTION OF AN ABAEN A VARIABILIS

The changes of Mn~(2 ) contents in Anabacna variabilis were probed by EPR.Treatments with CaCl_2 and Ca (NO_3)_2 at high concentrations induced the release of bound Mn and the decrease of oxygen-evolving activity of the cyanobacterium.When the release percentage of bound Mn reached up to 57%,the oxygen-evolving activity decreased to zero.MgCl_2 treat- ment resulted in less effectiveness than CaCl_3 MnCl-2 at high concentration inhibited cyanobac- terial oxygen evolution,as the indication of EGTA.In the comparision with control the low temperature fluorescence emission spectra of the cyanobacterium treated by CaCl_2,MgCl_2 and MnCl_2 changed with the shoulder disappearance at 686nm and the decline of ratio of F_(730)/F_(695) The possible competitive substitutions among ions at their binding sites in oxygen-evolving complex were discussed.