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测定了初步纯化的血小板肌动球蛋白的肌动蛋白激活的Mg~(2+)-ATP酶活力,并观察了丹参酮Ⅱ-A磺酸钠对此酶活性的影响。实验结果发现,丹参酮Ⅱ-A磺酸钠对此酶活性有抑制作用。此酶最大反应速度V_(max)=78.15μmol/L·min,米氏常数K_m=2.1×10~(-3)mol/L。在丹参酮Ⅱ-A磺酸钠存在下(0.721mmol/L),VV_(max)下降至29.14μmol/L·min,但K_m不变可见丹参酮Ⅱ-A磺酸钠对此酶具有非竞争性抑制作用。其抑制常数K_i=4.3×10~(-4)mol/L。这些结果表明丹参酮Ⅱ-A磺酸钠可能通过抑制血小板的肌动蛋白激活-Mg~(2+)-ATP酶活力而表现抑制血小板各种功能的药理作用。
The actin - activated Mg ~ (2 +) - ATPase activity of primary purified platelet actomyosin was measured and the effect of tanshinone Ⅱ-A sulfonate on the enzyme activity was also observed. The experimental results showed that tanshinone Ⅱ-A sulfonate inhibited this enzyme activity. The maximal reaction speed of this enzyme was V max = 78.15 μmol / L · min and the Km constant was 2.1 × 10 -3 mol / L. In the presence of sodium tanshinone Ⅱ-A sulfonate (0.721 mmol / L), the VV max decreased to 29.14 μmol / L · min, but K_m was unchanged, and tanshinone Ⅱ-A sulfonate showed noncompetitive inhibition effect. The inhibition constant K_i = 4.3 × 10 -4 mol / L. These results indicate that tanshinone Ⅱ-A sulfonate may exert the pharmacological action of inhibiting various functions of platelets by inhibiting actin activation of platelet-Mg (2 +) - ATPase.