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【目的】研究天蚕素A-马盖宁杂合肽对耐甲氧西林金黄色葡萄球菌(MRSA)DNA作用的抑菌机制。【方法】利用激光扫描共聚焦显微镜(CLSM)、凝胶阻滞分析、紫外光谱分析、荧光光谱分析的方法。【结果】天蚕素A-马盖宁杂合肽对MRSA的最小抑菌浓度(MIC)为64 mg/L,杂合肽可以在细菌胞内形成累积,并能与体外基因组DNA发生结合作用。同时杂合肽可以引起DNA构象的改变,荧光光谱分析结果表明杂合肽能与溴化乙锭(EB)竞争性地嵌入基因组DNA中,作用方式类似于EB与DNA的结合方式,杂合肽与DNA的结合表现为混合式作用方式。【结论】天蚕素A-马盖宁进入细菌胞内,与MRSA基因组DNA结合,并以混合式作用方式与DNA发生了结合,通过胞内靶向机制发挥抑菌作用。
【Objective】 To investigate the bacteriostasis mechanism of Cecropin A-Magainin hybrid peptide on methicillin-resistant Staphylococcus aureus (MRSA) DNA. 【Method】 Laser scanning confocal microscopy (CLSM), gel retardation analysis, ultraviolet spectroscopy and fluorescence spectroscopy were used. 【Result】 The minimum inhibitory concentration (MIC) of Cecropin A-Magainin on MRSA was 64 mg / L. The hybrid peptides could accumulate in the bacterial cells and bind to the genomic DNA in vitro. At the same time, the hybrid peptide can cause changes in the conformation of the DNA. Fluorescence spectroscopic analysis shows that the hybrid peptide can compete with ethidium bromide (EB) into the genomic DNA in a manner similar to the binding of EB to DNA. Hybrid peptides The combination with DNA shows a mixed mode of action. 【Conclusion】 Cecropin A-Magainin enters the bacterial cells, binds to MRSA genomic DNA, binds to DNA in a mixed mode of action, and exerts its antibacterial activity via an intracellular targeting mechanism.