农药林丹在磷脂酰胆碱双分子层中的扩散与分配。一种研究氯代烃与膜相互作用的新型荧光猝灭方法。
Diffusion and partitioning of a pesticide, lindane, into phosphatidylcholine bilayers. A new fluorescence quenching method to study chlorinated hydrocarbon-membrane interactions.
作者信息
Lakowicz J R, Hogen D, Omann G
出版信息
Biochim Biophys Acta. 1977 Dec 15;471(3):401-11. doi: 10.1016/0005-2736(77)90045-1.
Chlorinated hydrocarbons, such as the pesticide lindane (gamma-hexachlorocyclohexane), quench the fluorescence of carbazole. The observed quenching is a result of the molecular contacts which occur upon diffusional collisions. Because the amount of quenching depends upon the collisional frequency between carbazole and pesticide, this phenomenon provides a measure of both the diffusional rate of lindane and its local concentration. The carbazole fluorophore is localized within phosphatidylcholine bilayers by cosonicating the lipid with a newly synthesized phospholipid, beta-(11-(9-carbazole)-undecanoyl)-L-alpha-phosphatidylcholine. Using this probe in dimyristoyl-L-alpha-phosphatidylcholine vesicles, and the above mentioned quenching phenomena, we determined the lindane diffusion rate within the bilayer to be 5.7.10-7 cm2/s at 37 degrees C. Measurement of the apparent quenching constant at various dimyristoyl phosphatidylcholine concentrations yielded a lipid-water partition coefficient for lindane of 9500, which is in agreement with the value of 8980 obtained by our equilibrium dialysis experiments. Vesicles of dimyristoyl-L-alpha-phosphatidylcholine become saturated with lindane at a pesticide to lipid molar ratio of approx. 0.28. These results demonstrate the possibility of using the quenching of carbazole fluorescence to investigate the transport and partitioning of pesticides within biological membranes. This ability should prove useful in studies of the interactions of chlorinated hydrocarbons with cell membranes.
氯代烃，如农药林丹（γ-六氯环己烷），会淬灭咔唑的荧光。观察到的淬灭是扩散碰撞时发生分子接触的结果。由于淬灭量取决于咔唑与农药之间的碰撞频率，这种现象提供了一种测量林丹扩散速率及其局部浓度的方法。通过将脂质与新合成的磷脂β-(11-(9-咔唑)-十一烷酰基)-L-α-磷脂酰胆碱进行共超声处理，咔唑荧光团被定位在磷脂酰胆碱双层膜内。在二肉豆蔻酰-L-α-磷脂酰胆碱囊泡中使用该探针以及上述淬灭现象，我们测定出在37℃时，双层膜内林丹的扩散速率为5.7×10⁻⁷ cm²/s。在不同二肉豆蔻酰磷脂酰胆碱浓度下测量表观淬灭常数，得出林丹的脂水分配系数为9500，这与我们通过平衡透析实验得到的8980的值一致。当农药与脂质的摩尔比约为0.28时，二肉豆蔻酰-L-α-磷脂酰胆碱囊泡会被林丹饱和。这些结果证明了利用咔唑荧光淬灭来研究农药在生物膜内的运输和分配的可能性。这种能力在研究氯代烃与细胞膜的相互作用方面应该会很有用。
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