Feigin A M, Aronov E V, Teeter J H, Brand J G
Monell Chemical Senses Center, Philadelphia, PA 19104-3308.
Biochim Biophys Acta. 1995 Mar 8;1234(1):43-51. doi: 10.1016/0005-2736(94)00257-p.
The coumarin antibiotic novobiocin forms ion channels of varying conductances in lipid bilayers. The conductances (about 20, 22, 14, 7 and 2 pS for 100 mM NH4Cl, CsCl, KCl, NaCl and LiCl, respectively) and selectivities (cation transference numbers in the range of 0.97-0.98) of one type of novobiocin-induced channel are similar to those found for channels formed by gramicidin A, an antibiotic of very different structure. The conductance of novobiocin channels of this type was independent of the species of the membrane lipid. This observation suggests that novobiocin molecules directly form these channels, and that channels are not formed through defects in lipid structure. The similarity in conductance and ion selectivity between channels induced by novobiocin and those formed by gramicidin A suggests that these structurally different molecules form channels with comparable internal diameter and internal surface charge distribution. Using HPLC purification we argue that the channel-forming activity of novobiocin is related to the activity of the novobiocin molecule itself, and not to a contaminant of the commercially available novobiocin sodium salt preparation.
香豆素类抗生素新生霉素在脂质双分子层中形成具有不同电导率的离子通道。新生霉素诱导形成的一种通道的电导率（分别在100 mM氯化铵、氯化铯、氯化钾、氯化钠和氯化锂存在时约为20、22、14、7和2 pS）和选择性（阳离子迁移数在0.97 - 0.98范围内）与由短杆菌肽A形成的通道相似，短杆菌肽A是一种结构非常不同的抗生素。这种类型的新生霉素通道的电导率与膜脂种类无关。这一观察结果表明新生霉素分子直接形成这些通道，并且通道不是通过脂质结构缺陷形成的。新生霉素诱导的通道与短杆菌肽A形成的通道在电导率和离子选择性上的相似性表明，这些结构不同的分子形成了具有相当内径和内表面电荷分布的通道。通过高效液相色谱纯化，我们认为新生霉素的通道形成活性与新生霉素分子本身的活性有关，而不是与市售新生霉素钠盐制剂的污染物有关。
