Review accepted: Preparation of defined chitosan oligosaccharides using chitin deacetylases

Today, a review paper by our doctoral candidate Martin Bonin, our postdoctoral researchers Dr. Sruthi Sreekumar and Dr. Stefan Cord-Landwehr as well as Prof. Bruno Moerschbacher on the enzymatic production of structurally fully defined chitosan oligomers was accepted for publication in the Special Issue on “Complex Carbohydrates and Glycoconjugates: Structure, Functions and Applications” of the International Journal of Molecular Sciences. Such partially acetylated chitosan oligosaccharides (paCOS) are essential tools for the investigation of structure-function relationships of chitosans. This is one of the main research interests of our group, and we have sophisticated the biotechnological production, characterization, and use of regio-selective chitin deacetylases for paCOS production in the past years. These enzymes can specifically remove some acetyl groups, but not others, from fully acetylated chitin oligomers, producing paCOS with defined patterns of acetylation. Interestingly, the same enzymes can also catalyze the reverse direction, regio-selectively N-acetylating glucosamine oligomers in the presence of excess acetic acid, again producing defined paCOS. In the review, we describe the biotechnological production of the oligomeric substrates, their sequential conversion by different well-characterized chitin deacetylases, and the chromatographic purification as well as mass spectrometric characterization of the products. We hope that this comprehensive description will increase the awareness of the chitosan scientific community for the availability of such fully defined paCOS, stimulating their use for the understanding and exploitation of their diverse bioactivities. Eventually, we trust that this will lead to the development and optimization of reliable chitosan-based applications, e.g. in agriculture or biomedicine.