Tucker Matthew J, Tang Jia, Gai Feng
Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA.
J Phys Chem B. 2006 Apr 20;110(15):8105-9. doi: 10.1021/jp060900n.
The kinetics of peptide-membrane association have been studied previously using stopped-flow tryptophan fluorescence; however, such experiments do not directly report the coil-to-helix transition process, which is a hallmark of peptide-membrane interaction. Herein, we report a new method for directly assessing the kinetics of the helix formation accompanied by the peptide-membrane association. This method is based on the technique of fluorescence resonance energy transfer (FRET) and an amino acid FRET pair, p-cyano-L-phenylalanine and tryptophan. To demonstrate the utility of this method, we have studied the membrane-mediated helix folding dynamics of a mutant of magainin 2, an antibiotic peptide found in the skin of the African clawed frog, Xenopus laevis. Our results indicate that the coil-to-helix transition occurs during the binding of the peptide to the lipid vesicle (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine/1-palmitoyl-2-oleoyl-sn-glycero-3-[phospho-rac-(1-glycerol)], 3:1, wt/wt) but prior to the full insertion of the peptide into the hydrophobic region of the lipid bilayers.
此前已使用停流色氨酸荧光法研究了肽与膜结合的动力学；然而，此类实验并未直接报告从无规卷曲到螺旋的转变过程，而这是肽与膜相互作用的一个标志。在此，我们报告了一种直接评估伴随肽与膜结合的螺旋形成动力学的新方法。该方法基于荧光共振能量转移（FRET）技术以及一个氨基酸FRET对，即对氰基-L-苯丙氨酸和色氨酸。为了证明该方法的实用性，我们研究了非洲爪蟾（非洲爪蟾）皮肤中发现的一种抗菌肽——蛙皮抗菌肽2突变体的膜介导螺旋折叠动力学。我们的结果表明，从无规卷曲到螺旋的转变发生在肽与脂质囊泡（1-棕榈酰-2-油酰-sn-甘油-3-磷酸胆碱/1-棕榈酰-2-油酰-sn-甘油-3-[磷酸-rac-(1-甘油)]，3:1，重量/重量）结合的过程中，但在肽完全插入脂质双层的疏水区域之前。
