【摘要】 研究了低分子量壳聚糖及其O-羧甲基壳聚糖和O-羟乙基壳聚糖在不同质量分数和作用时间下,对大肠杆菌质粒DNA(pBR322和pUC18)的体外结合能力。研究结果表明,原料壳聚糖对2种质粒都有较强而稳定的结合能力;其2种衍生物对质粒的作用效果受空间位阻效应和氨基基团数量的共同影响,在适当的质量分数(≥1×10-2)和相对分子质量(2000,5000,8000及以上)的条件下,对质粒DNA都具有很强的结合能力。研究表明,壳聚糖及其衍生物对DNA的结合是基于正负电荷的静电吸引作用,结合过程短暂,结合能力不受作用时间的影响。相对分子质量为3000～5000的原料壳聚糖和O-羧甲基壳聚糖均可以有效阻碍mRNA的复制,且O-羧甲基壳聚糖在同等条件下影响作用较大,推测是由于此种衍生物对氨基的质子化能力较大和体积庞大造成。大肠杆菌体内转化实验表明,壳聚糖和O-羧甲基壳聚糖不仅可以和DNA结合而使之不能转化,而且可以直接阻碍正常质粒DNA向大肠杆菌的转化过程。更多还原

【Abstract】 The binding abilities of chitosan of low molecular mass and its water-soluble derivatives(O-CMCS and O-HECS) with of plasmids DNA pBR322 and pUC18 were studied in vitro at different mass fractions and reactive time.The results show that raw chitosan had strong effect on both plasmids and the influencing degrees were stable.The effect of the chitosan derivatives on the plasmids depended on space effect and the quantity of the amido groups.At appropriate mass fractions(larger than 1×10-2) and relative molecular mass(2 000,5 000,8 000 and higher than 8 000),the chitosan derivatives may have strong abilities to combine with DNA.The influencing degrees of chitosan and its derivatives on the plasmids have nothing to do with time,because the combination is based on charge attraction and the process is transitory.The experiment focused on the relationship between chitosans(with molecular Mass of 3 000～5 000) and mRNA showed that raw chitosan and O-CMCS could hinder the duplication of mRNA,and O-CMCS had a greater influence.The results might be caused by stronger protonating ability and huge volume of O-CMCS.The experiment of E.coli transfection in vivo showed that chitosan and O-CMCS can not only bind DNA but also directly hinder the transfection from the DNA to E.coli.更多还原