Study On Effects On E.Coli DNA And Protein Of Chitosan And Its Derivatives

In this paper, several chitosan water-soluble derivatives with low molecular weights (Mw) were synthesized. The antibacterial activities and water solubility were studied. O-carboxymethyl chitosan (O-CMCS) and N-methyl phosphoric chitosan (N-MPCS) were chosen out for biological experiments compared with chitosan. Binding abilities with plasmids DNA in vitro of chitosan and its derivatives were studied through agarose-gel electrophoresis and circular dichroism (CD) spectrum from four influencing factors. Effects on mRNA and E. coli transformation were also discussed. Preliminary study of influences on protein structure of chitosans was carried out using CD.The results showed: chitosan and its derivatives had different binding abilities with DNA and could hinder E. coli transformation. Binding abilities of chitosan and its derivatives with DNA would become stronger while concentration increased or degree of substitution (DS) decreased. O-CMCS with Mw less than 10000 had different abilities when binding with different plasmids and the effects were influenced by volume of plasmid and Mw of derivative. Study showed that O-CMCS had stronger influences on mRNA than chitosan. Chitosan and its two derivatives (O-CMCS and N-MPCS) with Mw of 10000 could hinder transformation process of E. coli and other derivatives did not have this ability. They could also loosen the structure of peptide. The ability would become larger as concentration increased or Mw and DS decreased. As above shows, it can be concluded that chitosan and its derivatives can bind with DNA and mRNA, resulting in interrupting the duplication. They also could hinder the process of transformation. These were the ways they had to restrain the growth of bacteria.