Article

Biochemistry (Moscow)

, Volume 73, Issue 4, pp 432-441

First online:

Interaction of chitosans and their N-acylated derivatives with lipopolysaccharide of gram-negative bacteria

  • G. A. NaberezhnykhAffiliated withPacific Institute of Bioorganic Chemistry, Far East Division of the Russian Academy of Sciences Email author 
  • , V. I. GorbachAffiliated withPacific Institute of Bioorganic Chemistry, Far East Division of the Russian Academy of Sciences
  • , G. N. LikhatskayaAffiliated withPacific Institute of Bioorganic Chemistry, Far East Division of the Russian Academy of Sciences
  • , V. N. DavidovaAffiliated withPacific Institute of Bioorganic Chemistry, Far East Division of the Russian Academy of Sciences
  • , T. F. Solov’evaAffiliated withPacific Institute of Bioorganic Chemistry, Far East Division of the Russian Academy of Sciences

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Abstract

The interactions of lipopolysaccharide (LPS) with the natural polycation chitosan and its derivatives—high molecular weight chitosans (80 kD) with different degree of acetylation, low molecular weight chitosan (15 kD), acylated oligochitosan (5.5 kD) and chitooligosaccharides (biose, triose, and tetraose)—were studied using ligand-enzyme solid-phase assay. The LPS-binding activity of chitosans (80 kD) decreased with increase in acetylation degree. Affinity of LPS interaction with chitosans increased after introduction of a fatty acid residue at the reducing end of chitosan. Activity of N-monoacylated chitooligosaccharides decreased in the order: oligochitosan → tetra-→ tri-→ disaccharides. The three-dimensional structures of complexes of R-LPS and chitosans with different degree of acetylation, chitooligosaccharides, and their N-monoacylated derivatives were generated by molecular modeling. The number of bonds stabilizing the complexes and the energy of LPS binding with chitosans decreased with increase in acetate group content in chitosans and resulted in changing of binding sites. It was shown that binding sites of chitooligosaccharides on R-LPS overlapped and chitooligosaccharide binding energies increased with increase in number of monosaccharide residues in chitosan molecules. The input of the hydrophobic fragment in complex formation energy is most prominent for complexes in water phase and is due to the hydrophobic interaction of chitooligosaccharide acyl fragment with fatty acid residues of LPS.

Key words

lipopolysaccharide chitosan binding computer simulation molecular docking