Patterns matter part 2: Chitosan oligomers with defined patterns of acetylation

摘要

Chitosans are linear, binary co-polymers of glucosamine and N-acetylglucosamine residues with interesting material properties and promising biological activities. Many of the biological activities of chitosan polymers are thought to be conveyed by their oligomeric breakdown products generated in situ by the action of sequence-specific chitosan hydrolases yielding partially acetylated chitosan oligosaccharides (paCOS) with partially or fully defined degrees of polymerisation (DP), fractions of acetylation (FA), and patterns of acetylation (PA). In this review, we summarize the state of the art concerning the production and analysis of defined chitosan oligomers as well as our current knowledge on the structure-function relationships of their bioactivities. Recent progress in this field was initially driven by the availability of increasing numbers of recombinant chitosan hydrolases with known and defined subsite specificities combined with improved chromatographic separation techniques for their products. This allowed insights into the roles of DP and FA in defining the biological activities of paCOS. More recently, the development is fuelled by the availability of equally well-defined recombinant chitin deacetylases in conjunction with improved mass spectrometric analysis tools for the structural characterisation of their products. This is currently enabling us to begin investigating the role of PA in defining biological activities.