【摘要】 外加5 mmol/L Ca²⁺可以使菠菜PSⅡ颗粒的放氧活性增高。PSⅡ颗粒经EGTA透析、低pH值、光照、2 mol/L NaCl等处理后,放氧活性下降,同时,这些颗粒的钙含量也相应降低。但当外加 5 mmol/L Ca²⁺时,可使这些颗粒全部或部分地恢复放氧活性。PSⅡ颗粒中存在的钙对放氧起着重要作用;钙在PSⅡ颗粒中的结合位点不止一个,其结合状态有紧密和松散之别。更多还原

【Abstract】 The addition of 5 mmol/L Ca²⁺ to reactionmixture caused an increase of O₂-evolutionactivity in purified spinach PS Ⅱ particle pre-paration. The O₂-evolution activity decreasedafter different treatments of PS Ⅱ particles:（1） dialysis against EGTA, （2） treatment witha solution of low pH, （3） illumination, （4） wash-ing with 2 mol/L NaC1 （Table 1）. The con-tent of Ca²⁺ in different particles were reducedsimultaneously （Table 4）. Howevcr, the O₂-evolution activity could be completely or par-tly restored by the addition of 5 mmol/L Ca²⁺.The results show that: the Ca²⁺ in PS Ⅱ parti-cles is essential to O₂-evolution activity; thereare more than one binding site of Ca²⁺ in PS Ⅱparticles,with different degree of tightness.更多还原