Daumas P, Benamar D, Heitz F, Ranjalahy-Rasoloarijao L, Mouden R, Lazaro R, Pullman A
Laboratory of Polyphasic System Physiochemistry, CNRS, Paris, France.
Int J Pept Protein Res. 1991 Sep;38(3):218-28. doi: 10.1111/j.1399-3011.1991.tb01432.x.
In order to elucidate the role of the aromatic side-chains in the mechanism of transduction of monovalent cations through the channel of linear gramicidin, two series of analogues containing non-coded aromatic amino acids were synthesized. In the first series, the four tryptophans were replaced by either four L-3-(8-quinolyl)alanyl or four L-3-(4-quinolyl)alanyl residues and single channel conductance measurements showed that these substitutions led to a strong lowering of the channel conductance, which is attributed to a modification of the orientation of the aromatic side-chains due to an increase of their hydrophobicity. In the second series, the analogues contained both tryptophyl and naphthylalanyl residues in various amounts and positions. The single channel conductance data indicated that the conductance was mainly governed by the number of polar residues (Trp) and not by their positions. The conformational consequences of these results are discussed together with their influence on the energy profile of the gramicidin channel.
为了阐明芳香族侧链在单价阳离子通过线性短杆菌肽通道的转导机制中的作用，合成了两个系列含有非编码芳香族氨基酸的类似物。在第一个系列中，四个色氨酸被四个L-3-(8-喹啉基)丙氨酰基或四个L-3-(4-喹啉基)丙氨酰基残基取代，单通道电导测量表明这些取代导致通道电导显著降低，这归因于芳香族侧链疏水性增加导致其取向发生改变。在第二个系列中，类似物含有不同数量和位置的色氨酰基和萘丙氨酰基残基。单通道电导数据表明，电导主要由极性残基（Trp）的数量而非其位置决定。讨论了这些结果的构象后果及其对短杆菌肽通道能量分布的影响。
