Nguyen Leonard T, Schibli David J, Vogel Hans J
Structural Biology Research Group, Department of Biological Sciences, University of Calgary, Calgary, Alberta, T2N 1N4 Canada.
J Pept Sci. 2005 Jul;11(7):379-89. doi: 10.1002/psc.629.
The powerful antimicrobial properties of bovine lactoferricin (LfcinB) make it attractive for the development of new antimicrobial agents. An 11-residue linear peptide portion of LfcinB has been reported to have similar antimicrobial activity to lactoferricin itself, but with lower hemolytic activity. The membrane-binding and membrane-perturbing properties of this peptide were studied together with an amidated synthetic version with an added disulfide bond, which was designed to confer increased stability and possibly activity. The antimicrobial and cytotoxic properties of the peptides were measured against Staphylococcus aureus and Escherichia coli and by hemolysis assays. The peptides were also tested in an anti-cancer assay against neuroblastoma cell lines. Vesicle disruption caused by these LfcinB derivatives was studied using the fluorescent reporter molecule calcein. The extent of burial of the two Trp residues in membrane mimetic environments were quantitated by fluorescence. Finally, the solution NMR structures of the peptides bound to SDS micelles were determined to provide insight into their membrane bound state. The cyclic peptide was found to have greater antimicrobial potency than its linear counterpart. Consistent with this property, the two Trp residues of the modified peptide were suggested to be embedded deeper into the membrane. Although both peptides adopt an amphipathic structure without any regular alpha-helical or beta-sheet conformation, the 3D-structures revealed a clearer partitioning of the cationic and hydrophobic faces for the cyclic peptide.
牛乳铁蛋白肽（LfcinB）强大的抗菌特性使其成为开发新型抗菌剂的理想选择。据报道，LfcinB的一个11个残基的线性肽段具有与乳铁蛋白本身相似的抗菌活性，但溶血活性较低。对该肽的膜结合和膜扰动特性以及一种添加了二硫键的酰胺化合成变体进行了研究，该变体旨在提高稳定性并可能增强活性。通过溶血试验测定了这些肽对金黄色葡萄球菌和大肠杆菌的抗菌和细胞毒性特性。这些肽还在针对神经母细胞瘤细胞系的抗癌试验中进行了测试。使用荧光报告分子钙黄绿素研究了这些LfcinB衍生物引起的囊泡破坏。通过荧光定量了膜模拟环境中两个色氨酸残基的埋藏程度。最后，测定了与SDS胶束结合的肽的溶液核磁共振结构，以深入了解它们的膜结合状态。发现环肽比其线性对应物具有更高的抗菌效力。与此特性一致，修饰肽的两个色氨酸残基被认为更深地嵌入膜中。尽管两种肽都采用两亲结构，没有任何规则的α-螺旋或β-折叠构象，但三维结构显示环肽的阳离子面和疏水面的划分更清晰。
