Hemmi Hikaru, Ishibashi Jun, Hara Seiichi, Yamakawa Minoru
National Food Research Institute, 2-1-12 Kannondai, Tsukuba, Ibaraki 305-8642, Japan.
FEBS Lett. 2002 May 8;518(1-3):33-8. doi: 10.1016/s0014-5793(02)02637-6.
A novel antibacterial peptide, moricin, isolated from the silkworm Bombyx mori, consists of 42 amino acids. It is highly basic and the amino acid sequence has no significant similarity to those of other antibacterial peptides. The 20 structures of moricin in methanol have been determined from two-dimensional 1H-nuclear magnetic resonance spectroscopic data. The solution structure reveals an unique structure comprising of a long alpha-helix containing eight turns along nearly the full length of the peptide except for four N-terminal residues and six C-terminal residues. The electrostatic surface map shows that the N-terminal segment of the alpha-helix, residues 5-22, is an amphipathic alpha-helix with a clear separation of hydrophobic and hydrophilic faces, and that the C-terminal segment of the alpha-helix, residues 23-36, is a hydrophobic alpha-helix except for the negatively charged surface at the position of Asp30. The results suggest that the amphipathic N-terminal segment of the alpha-helix is mainly responsible for the increase in permeability of the membrane to kill the bacteria.
一种从家蚕中分离出的新型抗菌肽——家蚕抗菌肽，由42个氨基酸组成。它具有高度碱性，其氨基酸序列与其他抗菌肽没有显著相似性。已根据二维¹H核磁共振光谱数据确定了家蚕抗菌肽在甲醇中的20种结构。溶液结构揭示了一种独特的结构，该结构由一个长的α-螺旋组成，除了四个N端残基和六个C端残基外，几乎沿着肽的全长包含八个螺旋圈。静电表面图显示，α-螺旋的N端片段（残基5-22）是一个两亲性α-螺旋，疏水和亲水表面明显分开，并且α-螺旋的C端片段（残基23-36）是一个疏水α-螺旋，除了在Asp30位置有带负电荷的表面。结果表明，α-螺旋的两亲性N端片段主要负责增加膜的通透性以杀死细菌。
