Hong Yooseong, Legge Raymond L, Zhang S, Chen P
Department of Chemical Engineering, University of Waterloo, 200 University Avenue, Waterloo, Ontario, Canada N2L 3G1.
Biomacromolecules. 2003 Sep-Oct;4(5):1433-42. doi: 10.1021/bm0341374.
Atomic force microscopy (AFM) and axisymmetric drop shape analysis-profile (ASDA-P) were used to investigate the mechanism of self-assembly of peptides. The peptides chosen consisted of 16 alternating hydrophobic and hydrophilic amino acids, where the hydrophilic residues possess alternating negative and positive charges. Two types of peptides, AEAEAKAKAEAEAKAK (EAK16-II) and AEAEAEAEAKAKAKAK (EAK16-IV), were investigated in terms of nanostructure formation through self-assembly. The experimental results, which focused on the effects of the amino acid sequence and pH, show that the nanostructures formed by the peptides are dependent on the amino acid sequence and the pH of the solution. For pH conditions around neutrality, one of the peptides used in this study, EAK16-IV, forms globular assemblies and has lower surface tension at air-water interfaces than another peptide, EAK16-II, which forms fibrillar assemblies at the same pH. When the pH is lowered below 6.5 or raised above 7.5, there is a transition from globular to fibrillar structures for EAK16-IV, but EAK16-II does not show any structural transition. Surface tension measurements using ADSA-P showed different surface activities of peptides at air-water interfaces. EAK16-II does not show a significant difference in surface tension for the pH range between 4 and 9. However, EAK16-IV shows a noticeable decrease in surface tension at pH around neutrality, indicating that the formation of globular assemblies is related to the molecular hydrophobicity.
原子力显微镜（AFM）和轴对称滴形分析-轮廓法（ASDA-P）被用于研究肽的自组装机制。所选用的肽由16个交替排列的疏水和亲水氨基酸组成，其中亲水残基带有交替的负电荷和正电荷。通过自组装形成纳米结构的角度，对两种类型的肽AEAEAKAKAEAEAKAK（EAK16-II）和AEAEAEAEAKAKAKAK（EAK16-IV）进行了研究。聚焦于氨基酸序列和pH影响的实验结果表明，肽形成的纳米结构取决于氨基酸序列和溶液的pH。对于接近中性的pH条件，本研究中使用的一种肽EAK16-IV形成球状聚集体，并且在空气-水界面处的表面张力低于另一种肽EAK16-II，后者在相同pH下形成纤维状聚集体。当pH降低到6.5以下或升高到7.5以上时，EAK16-IV会从球状结构转变为纤维状结构，但EAK16-II没有显示出任何结构转变。使用ADSA-P进行的表面张力测量表明，肽在空气-水界面处具有不同的表面活性。EAK16-II在4至9的pH范围内表面张力没有显著差异。然而，EAK16-IV在接近中性的pH下表面张力明显降低，这表明球状聚集体的形成与分子疏水性有关。
