Stark G, Strässle M, Takácz Z
J Membr Biol. 1986;89(1):23-37. doi: 10.1007/BF01870893.
The kinetics of formation and dissociation of channels formed by gramicidin A and two analogues in planar lipid membranes was studied using a laser temperature-jump technique developed earlier [Brock, W., Stark, G., Jordan, P.C. (1981), Biophys. Chem. 13:329-348]. The time course of the electric current was found to agree with a single exponential term plus a linear drift. In case of gramicidin A the relaxation time was identical to that reported for V-jump experiments [Bamberg, E., Läuger, P. (1973), J. Membrane Biol. 11:177-194], which were interpreted on the basis of a dimerization reaction. The same results were obtained for gramicidin A and for chemically dimerized malonyl-bis-desformylgramicidin. It is therefore suggested that the dimerization represents a parallel association of two dimers to a tetramer. There is evidence that the tetramer, contrary to the presently favored dimer hypothesis, is the smallest conductance unit of an active gramicidin channel. An additional V-jump-induced relaxation process of considerably larger time constant is interpreted as a further aggregation of gramicidin dimers.
利用先前开发的激光温度跳跃技术[布罗克，W.，斯塔克，G.，乔丹，P.C.（1981年），生物物理化学13:329 - 348]，研究了短杆菌肽A及其两种类似物在平面脂质膜中形成和解离通道的动力学。发现电流的时间进程与一个单指数项加上线性漂移相符。对于短杆菌肽A，弛豫时间与V跳跃实验[班贝格，E.，劳格，P.（1973年），膜生物学杂志11:177 - 194]报道的相同，该实验基于二聚化反应进行了解释。短杆菌肽A和化学二聚化的丙二酰 - 双 - 去甲短杆菌肽也得到了相同的结果。因此表明二聚化代表两个二聚体平行缔合形成一个四聚体。有证据表明，与目前流行的二聚体假说相反，四聚体是活性短杆菌肽通道的最小导电单位。另一个由V跳跃诱导的时间常数大得多的弛豫过程被解释为短杆菌肽二聚体的进一步聚集。
