Department of Chemical Engineering, Life Science and Bioengineering Center at Gateway Park Worcester Polytechnic Institute, 100 Institute Rd, Worcester, MA 01609, USA.
Colloids Surf B Biointerfaces. 2010 Jan 1;75(1):156-64. doi: 10.1016/j.colsurfb.2009.08.026. Epub 2009 Aug 21.
The antimicrobial peptide cecropin P1 (CP1) exhibits broad spectrum activity against planktonic bacteria, including Escherichia coli (E. coli). However, its activity when attached to a substrate has not been thoroughly studied. We immobilized CP1 to gold or silicon nitride, and studied how the method of attachment of peptide to the surface affected peptide interaction with and killing of the bacteria. Using the quartz crystal microbalance with dissipation monitoring (QCM-D), we characterized non-specific binding between CP1 to silicon nitride and gold, and covalent binding of cysteine-terminated CP1 (CP1-cys) to gold. The density of CP1-cys adsorbed on gold was more than the density of CP1 on silicon nitride, and activity against E. coli also depended on the method of attachment used to anchor the peptide to the surface. Twelve E. coli strains with known lipopolysaccharide (LPS) structures were studied. Bacterial adhesion with CP1 was strongest for E. coli with long O-antigens, as determined by atomic force microscopy (AFM). This may be caused by CP1 interacting with the hydrophilic part of the LPS, while control bacteria or those with short O-antigens had their hydrophobic lipid A region more exposed. Killing of E. coli due to contact with CP1 was dependent on the method by which the peptide was immobilized. Four out of 12 E. coli strains were killed when contacted with CP1-cys bound to gold via a thiol bond, while all 12 strains could be killed when in contact with CP1 on silicon nitride. In summary, both QCM-D adsorption experiments and adhesion forces measured by AFM showed a relationship between bacteria LPS length and binding or interaction with the antimicrobial peptide, but killing of E. coli by the peptide was most strongly dependent on how the peptide was attached to the surface.
抗菌肽 Cecropin P1 (CP1) 对浮游细菌具有广谱活性，包括大肠杆菌 (E. coli)。然而，其与基质结合后的活性尚未得到彻底研究。我们将 CP1 固定在金或氮化硅上，并研究了肽与表面结合的方式如何影响肽与细菌的相互作用和杀伤。我们使用石英晶体微天平耗散监测 (QCM-D) 来表征 CP1 与氮化硅和金之间的非特异性结合，以及半胱氨酸末端 CP1 (CP1-cys) 与金的共价结合。CP1-cys 在金上的吸附密度高于 CP1 在氮化硅上的吸附密度，肽与表面结合的方式也影响其对大肠杆菌的活性。我们研究了 12 株具有已知脂多糖 (LPS) 结构的大肠杆菌。通过原子力显微镜 (AFM) 确定，CP1 与 LPS 长 O-抗原的大肠杆菌的粘附最强。这可能是因为 CP1 与 LPS 的亲水部分相互作用，而对照细菌或 O-抗原较短的细菌则使其疏水性脂质 A 区域更多地暴露。由于与 CP1 接触而导致的大肠杆菌的杀伤取决于肽固定的方式。当通过硫醇键将 CP1-cys 固定在金上时，有 4 株大肠杆菌被杀死，而当 CP1 固定在氮化硅上时，所有 12 株大肠杆菌都可以被杀死。总之，QCM-D 吸附实验和 AFM 测量的粘附力都表明了细菌 LPS 长度与抗菌肽的结合或相互作用之间存在关系，但肽对大肠杆菌的杀伤作用最强烈地取决于肽与表面的结合方式。
