热胁迫对葡萄叶片中蛋白激酶活性的影响

 以葡萄品种京秀（Vitis vinifera L. cv. Jingxiu）一年生扦插苗为试材，40℃高温处理30 min，并以25℃为对照，采用体外底物磷酸化方法对叶片中蛋白激酶的活性进行了测定。结果表明，热胁迫处理后，叶片中蛋白激酶在底物髓鞘碱性蛋白(myelin basic protein，MBP)浓度为0.5 mg·ml-1时，其活性达到最大(7 678.7 cpm)，而后随底物浓度的进一步增加，其活性下降。Mg2+浓度为5 mmol·L-1时，蛋白激酶活性达到最大(8 165.8 cpm)。Ca2+对蛋白激酶活性的影响极弱，Mn2+对蛋白激酶活性的激活没有影响。ATP浓度为50 μmol·L-1时，蛋白激酶的活性最大（7 900.9 cpm），比对照高4.7倍。在以组蛋白-Ⅲ（histone-Ⅲ）为底物时，蛋白激酶的活性很微弱，且Mg2+和Ca2+对蛋白激酶有极弱的激活作用。

Influence of Heat Stress on the Activity of Protein Kinase in Grape Leaves

Abstract: One-year-old grape plants （Vitis vinifera L. cv. Jingxiu） by cuttage were used as experimental materials. The activity of protein kinase in grape leaves after treatment of heat stress (40℃) was measured through substrate phosphorylation in vitro. The results showed that the activity of protein kinase in leaves after heat stress reached a peak value(7 678.7 cpm) as MBP concentration was 0.5 mg·ml-1, and then the activity of protein kinase decreased slightly as MBP concentration increased continuously. The activity of protein kinase exhibited a maximum value as Mg2+ concentration was 5 mmol·L-1 in reaction system with MBP substrate, and then, the activity of protein kinase decreased. Stimulation by Ca2+ to the activity of protein kinase was extremely weak. Mn2+ had no stimulative effect on the activity of protein kinase. Phosphorylation of protein kinase to histone-Ⅲ was weak in reaction system with histone-Ⅲ substrate. Mg2+ and Ca2+ displayed extremely weak effect on kinase activity in the reaction system with histone-Ⅲ substrate. The activity of protein kinase reached a peak value (7 900.9 cpm) as ATP concentration was 50μmol·L-1, then, the activity of protein kinase decreased gradually as ATP concentration increased continuously .