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汉防己的有效成份汉防己甲素(Tet)在较低浓度时能抑制钙调蛋白(CaM)依赖性环核苷酸磷酸二酶(PDE)的活性(IC_(50)=43μmol/L),并且这种抑制能被 CaM 所对抗;而在较高浓度(>300μmol/L)时,无论有无 Ca~(2+)和 CaM 的存在,Tet 均能非 Ca~(2+)依赖性激活 PDE,这种激活不受 CaM 拮抗剂三氟拉嗪和氯丙嗪的影响。结果提示,Tet 既具有抗 CaM 作用,又能在较高浓度时直接与 PDE 相互作用而部分模拟CaM 的作用,这可能均与 Tet 的水、脂两性分子特性有关。该实验为阐明中药的作用机理及 CaM 与其靶酶相互作用的研究提供了新线索。
Tetratoxin (Tet), the active ingredient of Tetrandrine, inhibits the activity of CaM-dependent cyclic nucleotide phosphodiesterase (PDE) at a lower concentration (IC 50 = 43 μmol / L) And this inhibition could be antagonized by CaM; while at higher concentrations (> 300 μmol / L), Tet was able to activate Ca 2+ -dependently with and without Ca 2+ PDE, this activation is not affected by the CaM antagonists trifluoperazine and chlorpromazine. The results suggest that Tet has both anti-CaM effects and partially interacts with PDE at higher concentrations to partially mimic the effect of CaM, both of which may be related to Tet’s water and lipid amphipathic molecular properties. The experiment provides new clues for elucidating the mechanism of action of traditional Chinese medicine and the interaction between CaM and its target enzyme.