McLean L R, Hagaman K A
Marion Merrell Dow Research Institute, Cincinnati, OH 45215.
Biochim Biophys Acta. 1993 Apr 23;1167(3):289-95. doi: 10.1016/0005-2760(93)90231-w.
The rate of association of three amphipathic alpha-helical peptides with phosphatidylcholine liposomes was examined to provide more detailed information on the relationship between peptide length and the kinetics of lipid interactions. When added to dimyristoylphosphatidylcholine (DMPC) or dipalmitoylphosphatidylcholine (DPPC) liposomes from a guanidine-HCl solution, a ten residue peptide rapidly decreased the turbidity of the liposomes. However, a related 17-residue peptide had only a minimal effect on liposome turbidity. A 14-residue peptide was intermediate in effectiveness. Similarly, when liposomes were added to peptides dissolved in an aqueous buffer, the ten residue peptide but not the 17-residue peptide cleared the turbid liposomes and the 14-residue peptide was intermediate in efficacy. The rate of binding to the liposomes was compared with the three peptides by measurements of the kinetics of energy transfer from the single tryptophan residue of the peptides to a fluorescent probe in the bilayer interior. The tryptophan residue of the ten residue peptide effectively transferred energy to the probe, while that of the 14-residue peptide was less effective. Little or no energy transfer was observed with the 17-residue peptide. The binding of the 10 residue peptide was rapid and complete within < 100 ms. The 14-residue peptide bound more slowly, but still within seconds. The time frames for binding are an order of magnitude shorter than those observed for lipid clearing. The relationship between peptide length, liposome clearing and lipid binding kinetics is discussed in terms of a possible competing peptide-peptide interaction in the aqueous phase and a slow rearrangement of the lipid bilayer.
研究了三种两亲性α-螺旋肽与磷脂酰胆碱脂质体的结合速率，以提供关于肽长度与脂质相互作用动力学之间关系的更详细信息。当从盐酸胍溶液中添加到二肉豆蔻酰磷脂酰胆碱（DMPC）或二棕榈酰磷脂酰胆碱（DPPC）脂质体中时，一个十肽残基的肽迅速降低了脂质体的浊度。然而，一个相关的17肽残基的肽对脂质体浊度的影响极小。一个拥有14肽残基的肽在有效性方面处于中间水平。同样，当将脂质体添加到溶解于水性缓冲液中的肽中时，十肽残基的肽能使浑浊的脂质体变清，而17肽残基的肽则不能，14肽残基的肽在功效上处于中间水平。通过测量从肽的单个色氨酸残基到双层内部荧光探针的能量转移动力学，比较了这三种肽与脂质体的结合速率。十肽残基肽的色氨酸残基有效地将能量转移到了探针上，而14肽残基肽的色氨酸残基的效果则较差。对于17肽残基的肽，几乎没有观察到能量转移。10肽残基肽的结合迅速且在<100毫秒内完成。14肽残基肽结合得较慢，但仍在数秒内完成。结合的时间框架比脂质清除所观察到的时间框架短一个数量级。根据水相中可能存在的肽-肽竞争相互作用以及脂质双层的缓慢重排，讨论了肽长度、脂质体清除和脂质结合动力学之间的关系。
