钙延缓黄瓜子叶衰老及其对RNase与活性氧清除有关酶活性的反应

Deferment of Cucumber Cotyledon with Calcium and Its Effect on Activity of RNase and Enzymes Related to Radical Seayengers

在黄瓜子叶衰老期间外源 Ca^(2+)延缓内源结合 Ca^(2+)和总 Ca^(2+)含量的降低.Ca^(2+)处理5d的子叶,各亚细胞结构部分 RNase 活力均有明显的抑制效应,但不同亚细胞组分的反应程度不尽相同,线粒体对外源 Ca^(2+)处理最敏感,叶绿体则较迟钝,1mMCa^(2+)处理的子叶,SOD 活力高于对照47%.10mMCa^(2+)处理的子叶仅是对照的48%,Ca^(2+)对衰老过程中 SOD 活力作用可能与体内 Ca·CaM 系统有关.子叶衰老过程中过氧化物酶和过氧化氯酶活力均受到 Ca^(2+)的刺激.但 Ca^(2+)对过氧化氢酶活力刺激效应比过氧物酶小得多.上述结果表明,Ca^(2+)的作用可能与体内自由基清除有关的酶有关;外源 Ca^(2+)对暗诱导黄瓜子叶过氧化物酶作用通过释放胞壁以离子键结合的酶来完成.

The cotyledons of cucumber growing for 10 days were used in theexperiment.The senescence came into being through cotyledons inducedin darkness.The treatment of exogenous Ca^(2+)deferred the decrease ofendogenous bound calcium and total calcium content during the senescence.The treatment of Ca^(2+)made chlorophyll content stay on a high level.Protein contents of Ca^(2+)treatment group were higher than those under thecontrol.The activity of RNase Extract of Ca^(2+)treatment was lower thanthat under the control.The reaction degree of the activity of RNase indifferent compartments of the cell was different from each other.Themit.was the most sensitive to Ca^(2+).The chl.in sensitive to it.SODactivity of the treatment of 1mmol/L Ca^(2+)was 47% higher than thatunder the control.The percentage was only 48% when treated with10mmol/L Ca^(2+).Effects of Ca^(2+)on SOD during the senescence may berelated with endogenous CaCAM system.The activity of peroxidase andcatalase was irritated by Ca^(2+)treatment in the process of senescence.The reaction of Ca^(2+)treatment on catalase activity was much lower thanthat on the peroxidase's.When 1mmol/L Ca^(2+)was used,the activityof soluble peroxidase increased 18.40%,higher than that of the iron-bondand the covalent bonds in the cell wall decreased 15.49% and 0.50%respectively.This suggests that effects of Ca^(2+)on the activity of solubleperoxidase may have another path in addifion to the release of peroxidasefrom the cell wall.What is described above suggests that the exogenousCa^(2+)of 0.1-10mmol/L can defer the process of the senescence ofcucumber cotyledons detached,that the activity of Ca^(2+)may be relatedto the endogenous radical scavengers and that the effects of Ca^(2+)onperoxidase are carried out by the release of iron-bond-enzyme bound inthe cell walls.