Tang Ming, Waring Alan J, Hong Mei
Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA.
J Am Chem Soc. 2005 Oct 12;127(40):13919-27. doi: 10.1021/ja0526665.
The aggregation and packing of a membrane-disruptive beta-hairpin antimicrobial peptide, protegrin-1 (PG-1), in the solid state are investigated to understand its oligomerization and hydrogen-bonding propensity. Incubation of PG-1 in phosphate buffer saline produced well-ordered nanometer-scale aggregates, as indicated by 13C and 15N NMR line widths, chemical shifts, and electron microscopy. Two-dimensional 13C and 1H spin diffusion experiments using C-terminus strand and N-terminus strand labeled peptides indicate that the beta-hairpin molecules in these ordered aggregates are oriented parallel to each other with like strands lining the intermolecular interface. In comparison, disordered and lyophilized peptide samples are randomly packed with both parallel and antiparallel alignments. The PG-1 aggregates show significant immobilization of the Phe ring near the beta-turn, further supporting the structural ordering. The intermolecular packing of PG-1 found in the solid state is consistent with its oligomerization in lipid bilayers. This solid-state aggregation approach may be useful for determining the quaternary structure of peptides in general and for gaining insights into the oligomerization of antimicrobial peptides in lipid bilayers in particular.
为了解膜破坏型β-发夹抗菌肽protegrin-1（PG-1）的寡聚化和氢键形成倾向，对其固态下的聚集和堆积情况进行了研究。13C和15N NMR线宽、化学位移以及电子显微镜结果表明，PG-1在磷酸盐缓冲盐水中孵育会产生有序的纳米级聚集体。使用C端链和N端链标记肽进行的二维13C和1H自旋扩散实验表明，这些有序聚集体中的β-发夹分子彼此平行排列，相同的链排列在分子间界面处。相比之下，无序的冻干肽样品则以平行和反平行排列的方式随机堆积。PG-1聚集体在β-转角附近的苯丙氨酸环表现出显著的固定化，进一步支持了结构的有序性。固态下发现的PG-1分子间堆积与其在脂质双层中的寡聚化情况一致。这种固态聚集方法可能普遍有助于确定肽的四级结构，尤其有助于深入了解抗菌肽在脂质双层中的寡聚化过程。
