摘要
抗菌肽的抗菌机理研究主要集中在抗菌肽与细菌细胞膜作用方面,抗菌肽是否与细菌的染色体DNA作用尚不清楚。为了探讨新疆家蚕抗菌肽Cecropin-XJ抗细菌的作用机理,利用紫外光谱及以溴化乙锭(EthidiumBromide,EB)为荧光探针的荧光光谱方法研究抗菌肽Cecropin-XJ与金黄色葡萄球菌DNA在体外的相互作用,计算获得抗菌肽与DNA的结合常数和成键位点数。结果显示,抗菌肽使DNA发生了明显的增色效应,并使DNA的荧光强度增强,抗菌肽能与EB竞争性的结合DNA,表明抗菌肽可能与DNA双螺旋的沟槽结合;在抗菌肽存在下,DNA与EB作用的结合常数和成键位点数都发生变化,表明抗菌肽以嵌入和非嵌入两种方式与DNA相互作用。文章从分子水平上初步阐述了抗菌肽与细菌DNA的作用模式和结构特征,为深入研究抗菌肽的作用机理奠定了基础。
Nowadays many of antimicrobial peptides have been extensively studied in order to elucidate
their antimicrobial mode of action.Much of the research focused on mechanisms of cytoplasmic
membrane disruption has been proposed for antimicrobial peptides,but it is not known whether
their antimicrobial mode of action is due to their effects on bacterial chromosome.To obtain more
information about the possible mechanisms,Cecropin-XJ,a kind of antimicrobial peptide from
Xinjiang silkworm,was used as subject and prepared by purification of Pichia yeast fermentation
containing cecropin-XJ gene expression product.Subsequently,ultraviolet absorption spectra were
employed to investigate whether this antibacterial function is due to Cecropin-XJ works on
S.aureus DNA in vitro.The increase in absorbance of DNA samples at 260nm due to the addition of
Cecropin-XJ was measured.It is called hyperchromicity of DNA,which can provide a direct measure
of the degree of base-pair unstacking.The unstacking results in the loss of duplex helix,and then
leads to the duplex helix becoming relaxing.At the same time,the interaction mode was studied by
using ethidium bromide（EB） as an extrinsic fluorescence probe.With the addition of
Cecropin-XJ,the intensity of intrinsic fluorescence absorbance of DNA at 307 nm increases
greatly.It is suggested that the addition of Cecropin-XJ may unstack base-paire of DNA exposing
the fluorescent amino acide,leading to the enhancing of DNA fluorescence intensity.Subsequently
the competition between Cecropin-XJ and EB to combine with DNA was found.It is suggested that the
style was groove binding and intercalation in the interaction of Cecropin-XJ and double helix
DNA.Furthermore,in this study,the binding constant and binding number of Cecropin-XJ complex with
DNA were determined.There were different binding constant and number of EB complex with DNA
because of the the addition of Cecropin-XJ.It is showed that the interaction of Cecropin-XJ and
DNA was based on intercalation or non-intercalation.Meanwhile,these results help explain the
molecule mechanism of antimicrobial peptide from the interaction style and structure
characteristic of Cecropin-XJ and S.aureus DNA.These findings could contribute to further
investigation on the mechanism of action of Cecropin-XJ.
出处
《光谱学与光谱分析》
SCIE
EI
CAS
CSCD
北大核心
2008年第3期612-616,共5页
Spectroscopy and Spectral Analysis
基金
新疆自治区高技术研究与发展计划项目(200311118)
高校科研计划青年教师科研基金(XJEDU2006S04)资助
