Abstract: 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 .

Key words: Heat stress, Grape, Leave, Protein kinase, Activity